HA17384SPS/SRP, HA17384HPS/HRP,

HA17385HPS/HRP

High Speed Current Mode PWM Control IC

for Switching Power Supply

ADE-204-028A (Z)

2nd Edition

Nov. 1999

Description

The HA17384S/H and HA17385H are PWM control switching regulator IC series suitable for highspeed,
current-mode switching power supplies. With ICs from this series and a few external parts, a small, low
cost flyback-transformer switching power supply can be constructed, which facilitates good line regulation
by current mode control. Synchronous operation driven after an external signal can also be easily obtained
which offers various applications such as a power supply for monitors small multi-output power supply.

The IC series are composed of circuits required for a switching regulator IC. That is a under-voltage
lockout (UVL), a high precision reference voltage regulator (5.0 V ± 2%), a triangular wave oscillator for
timing generation, a high-gain error amplifier, and as totem pole output driver circuit which directly drives
the gate of power MOSFETs found in main switching devices. In addition, a pulse-by-pulse type, high-
speed, current-detection comparator circuit with variable detection level is incorporated which is required
for current mode control.

The HA17384SPS includes the above basic function circuits. In addition to these basic functions, the H
Series incorporates thermal shut-down protection (TSD) and overvoltage protection (OVP) functions, for
configuration of switching power supplies that meet the demand for high safety levels.

Between the HA17384 and HA17385, only the UVL threshold voltages differ as shown in the product
lineup table.(See next page.)

This IC is pin compatible with the "3842 family" ICs made by other companies in the electronics industry.
However, due to the characteristics of linear ICs, it is not possible to achieve ICs that offer full
compatibility in every detail.

Therefore, when using one of these ICs to replace another manufacturer's IC, it must be recognized that it
has different electrical characteristics, and it is necessary to confirm that there is no problem with the power
supply (mounting) set used.

HA17384SPS/SRP, HA17384HPS/HRP, HA17385HPS/HRP

Functions

Under-voltage lockout system

Reference voltage regulator of 5.0 V ± 2%

Triangular wave (sawtooth) oscillator

Error amplifier

Totem pole output driver circuit (direct driving for power MOSFETs)

Current-detection comparator circuit for current mode

OVP function (over voltage protection) *

TSD function (thermal shut-down protection) *

Protect function by zener diode (between power input and GND)

Note: 1. H series only.

Features

High-safety UVL circuit is used (Both V

and Vref are monitored)

High speed operation:

Current detection response time: 100 ns Typ

Maximum oscillation frequency: 500 kHz

Low standby current: 170

A Typ

Wide range dead band time

(Discharge current of timing capacitance is constant 8.4 mA Typ)

Able to drive power MOSFET directly

(Absolute maximum rating of output current is ±1 A peak)

OVP function (over voltage protection) is included *

(Output stops when FB terminal voltage is 7.0 V Typ or higher)

TSD function (thermal shut-down protection) is included *

(Output stops when the temperature is 160°C Typ or higher)

Zener protection is included

(Clamp voltage between V

and GND is 34 V Typ)

Wide operating temperature range:

Operating temperature: 20°C to +105°C

Junction temperature: 150°C *

Note: 1. H series only.

2. S series only.

HA17384SPS/SRP, HA17384HPS/HRP, HA17385HPS/HRP

Product Line-up

Package

Additional Function

UVL Power Supply
Threshold Voltage

DILP8 (DP-8)

SOP8 (FP-8DC)

TSD
(Thermal shut-
down protection)

OVP
(Over voltage
protection)

TH UVL

(V) Typ

TL UVL

(V) Typ

HA17384SPS

HA17384SRP

16.0

10.0

HA17384HPS

HA17384HRP

HA17385HPS

HA17385HRP

8.4

7.6

Pin Arrangement

COMP

Vref

OUT

GND

(Top view)

Pin Function

Pin No.

Symbol

Function

Note

COMP

Error amplifier output pin

Inverting input of error amp./OVP input pin

Current sensing signal input pin

Timing resistance, timing capacitance connect pin

GND

Groung pin

OUT

PWM Pulse output pin

Power supply voltage input pin

Vref

Reference voltage 5V output pin

Note:

1. Overvoltage protection (OVP) input is usable only for the HA17384H and HA17385H.

HA17384SPS/SRP, HA17384HPS/HRP, HA17385HPS/HRP

Absolute Maximum Ratings

Item

Symbol

Rating

Unit

Note

Supply voltage

DC output current

0.1

Peak output current

O PEAK

1.0

Error amplifier input voltage

0.3 to V

COMP terminal input voltage

COMP

0.3 to +7.5

Error output sink current

OEA

Power dissipation

680

1, 2

Operating temperature

Topr

20 to +105

Junction temperature

125

150

Storage temperature

Tstg

55 to +125

55 to +150

Notes: 1. For the HA17384HPS and HA17385HPS,

This value applies up to Ta = 43

C; at temperatures above this, 8.3 mW/

C derating should be

applied.

For the HA17384SPS,

This value applies up to Ta = 68

C; at temperatures above this, 8.3 mW/

C derating should be

applied.

Power Dissipation P

(mW)

Ambient Temperature Ta (

680mW

374mW

150

800

600

400

200

100

120

140

160

166mW

105

125

HA17384SPS

HA17384HPS, HA17385HPS

HA17384SPS/SRP, HA17384HPS/HRP, HA17385HPS/HRP

Absolute Maximum Ratings (cont)

Notes: 2. This is the value when the device is mou nted on a glass-epoxy substrate (40 mm

40 mm

1.6

mm). However,

For the HA17384HRP and HA17385HRP,

Derating should be performed with 8.3 mW/

C in the Ta

C range if the substrate wiring

density is 10%.

Derating should be performed with 11.1 mW/

C in the Ta

C range if the substrate wiring

density is 30%.

For the HA17384SRP,

Derating should be performed with 8.3 mW/

C in the Ta

C range if the substrate wiring

density is 10%.

Derating should be performed with 11.1 mW/

C in the Ta

C range if the substrate wiring

density is 10%.

Power Dissipation P

(mW)

Ambient Temperature Ta (

374 mW

680 mW

150

800

600

400

200

100

120

140

160

166 mW

500 mW

222 mW

105

125

HA17384SRP
:

11.1 mW/

C (wiring density is 30%)

8.3 mW/

C (wiring density is 10%)

HA17384HRP, HA17385HRP
:

11.1 mW/

C (wiring density is 30%)

8.3 mW/

C (wiring density is 10%)

3. Applies to the HA17384HPS/HRP and HA17385HPS/HRP.

4. Applies to the HA17384SPS/SRP.

HA17384SPS/SRP, HA17384HPS/HRP, HA17385HPS/HRP

Electrical Characteristics
(The condition is: Ta = 25°C, V

= 15 V, C

= 3300 pF, R

= 10 k

without notice)

Reference Part

Item

Symbol

Min

Typ

Max

Unit

Test Condition

Note

Reference output voltage

Vref

4.9

5.0

5.1

Io = 1 mA

Line regulation

Regline

12 V

25 V

Load regulation

Regload

1 mA

20 mA

Output short current

los

100

180

Vref = 0V

Temperature stability

Vref

ppm/

Io = 1 mA,
20

105

Output noise voltage

100

10 Hz

fnoise

10 kHz

Notes: 1. Reference value for design.

Triangular Wave Oscillator Part

Item

Symbol

Min

Typ

Max

Unit

Test Condition

Note

Typical oscillating frequency

fosc Typ

kHz

= 3300 pF,

= 10 k

Maximum oscillating
frequency

fosc Max

500

kHz

Supply voltage dependency of
oscillating frequency

fosc 1

0.5

2.0

12 V

25 V

Temperature dependency of
oscillating frequency

fosc 2

5.0

105

Discharge current of C

Isink

7.5

8.4

9.3

= 2.0 V

Low level threshold voltage

TLCT

1.2

High level threshold voltage

THCT

2.8

Triangular wave amplitude

1.6

= V

THCT

TLCT

Notes: 1. Reference value for design.

HA17384SPS/SRP, HA17384HPS/HRP, HA17385HPS/HRP

Electrical Characteristics (cont)

Error Amplifire Part / OVP Part

Item

Symbol

Min

Typ

Max

Unit

Test Condition

Note

Non-inverting input voltage

2.42

2.50

2.58

COMP

= 2.5 V

Input bias current

0.2

2.0

= 5.0 V

Open loop voltage gain

VOL

2.0 V

4.0 V

Unity gain bank width

0.7

1.0

MHz

Power supply voltage
rejection ratio

PSRR

12 V

25 V

Output sink current

Osink EA

3.0

9.0

= 2.7 V, V

COMP

= 1.1 V

Output source current

Osource EA

0.5

0.8

= 2.3 V, V

COMP

= 5.0 V

High level output voltage

OH EA

5.5

6.5

7.5

= 2.3 V,

= 15 k

(GND)

Low level output voltage

OL EA

0.7

1.1

= 2.7 V,

= 15 k

(Vref)

OVP latch threshold
voltage

OVP

6.0

7.0

8.0

Increase FB terminal
voltage

OVP (FB) terminal input
current

FB(OVP)

= 8.0 V

OVP latch reset V

voltage

IN(OVP RES)

6.0

7.0

8.0

Decreasing V

after OVP

latched

Note:

1. These values are not prescribe to the HA17384SPS/SRP because OVP function is not included.

HA17384SPS/SRP, HA17384HPS/HRP, HA17385HPS/HRP

Electrical Characteristics (cont)

Current Sensing Part

Item

Symbol

Min

Typ

Max

Unit

Test Condition

Note

Voltage gain

VCS

2.85

3.00

3.15

V/V

= 0 V

Maximum sensing voltage

Vth

0.9

1.0

1.1

Power supply voltage
rejection ratio

PSRR

12 V

25 V

Input bias current

BCS

= 2 V

Current sensing
response time

tpd

100

150

Time from when V

becomes 2 V to when
output becomes "L" (2 V)

Notes: 1. The gain this case is the ratio of error amplifier output change to the current-sensing threshold

voltage change.

2. Reference value for design.

3. Current sensing response time tpd is definded a shown in the figure 1.

OUT

(PWM)

Vth

tpd

Figure 1 Definition of Current Sensing Response Time tpd

PWM Output Part

Item

Symbol

Min

Typ

Max

Unit

Test Condition

Note

Output low voltage 1

OL1

0.7

1.5

losink = 20 mA

Output low voltage 2

OL2

1.5

2.2

losink = 200 mA

Output high voltage 1

OH1

13.0

13.5

losource = 20 mA

Output high voltage 2

OH2

12.0

13.3

losource = 200 mA

Output low voltage at
standby mode

OL STB

0.8

1.1

= 5 V,

losink = 1 mA

Rise time

150

= 1000 pF

Fall time

130

= 1000 pF

Maximum ON duty

Du max

100

Minimum ON duty

Du min

Notes: 1. Pulse application test

HA17384SPS/SRP, HA17384HPS/HRP, HA17385HPS/HRP

Electrical Characteristics (cont)

UVL Part

Item

Symbol

Min

Typ

Max

Unit

Test Condition

Note

Threshold voltage for

TH UVL

14.5

16.0

17.5

Turn-ON voltage

high V

level

7.6

8.4

9.2

when V

is rising

Threshold voltage for

TL UVL

9.0

10.0

11.0

Minimum operating

low V

level

6.8

7.6

8.4

voltage after turn-ON

UVL hysteresis voltage

HYS UVL

5.0

6.0

7.0

HYS UVL

= V

TH UVL

TL UVL

0.6

0.8

1.0

Vref UVL threshold voltage

T Vref

4.3

4.7

Vref

Voltage is forced toVref
terminal

Notes: 1. For the HA17384S/H.

2. For the HA17385H.

Total Characteristics

Item

Symbol

Min

Typ

Max

Unit

Test Condition

Note

Operating current

7.0

10.0

13.0

= 1000 pF, V

= V

= 0 V

Standby current

STBY

120

170

230

Current at start up

Current of latch

LATCH

200

270

340

= 0 V after V

= V

OVP

1, 2

Power supply zener
voltage

INZ

+ 2.5 mA

Overheat protection
starting temperature

TSD

160

3, 4

Notes: 1. These values are not prescribe to the HA17384SPS/SRP because OVP function is not included.

2. V

= 8.5 V in case of the HA17384H.

2. These values are not prescribe to the HA17384SPS/SRP because TSD function is not included.

4. Reference value for design.

HA17384SPS/SRP, HA17384HPS/HRP, HA17385HPS/HRP

Timing Chart

Waveform timing (Outline)

Signal Name

Input voltage
V

Pin 7

UVL1
Internal signal which
cannot be externally
monitored.

Reference voltage
Vref Pin 8

UVL2
Internal signal which
cannot be externally
monitored.

Oscillation voltage of
triangular wave
R

Pin 4

Start up signal
Internal signal which
cannot be externally
monitored.

PWM latch setting signal
internal signal which
cannot be externally
monitored.

Error amplifier input signal
V

Pin 2

Error amplifier output signal
V

COMP

Pin 1

OVP latch signal
Internal signal which
cannot be externally
monitored.

Power ON

IC turn ON

Stationary operation

OVP input

OVP latched
condition

Power OFF

Reset of
OVP latch

Start up latch
release

( ) shows the case
using HA17385H

PWM output voltage
V

OUT

Pin 6

Note: 1. I

indicates the power MOSFET drain current; it is actually observed as voltage V

generated

by power MOSFET current detection source resistance R

COMP

indicates the error amp output voltage waveform. Current mode operation is

performed so that a voltage 1/3 that of V

COMP

is the current limiter level.

10 V

(7.6 V)

7.0 V
2 V

16 V

(8.4 V)

2 V

5 V

4.7 V

2.8 V

1.2 V

7.0 V typ

(OVP input)

COMP

4.7 V

IC operates and
PWM output stops.

This voltage is determined
by the transformer

HA17384SPS/SRP, HA17384HPS/HRP, HA17385HPS/HRP

Operation (Description of Timing Chart)

From Power ON to Turn On

After the power is switched ON, the power supply terminal voltage (V

) of this IC rises by charging

through bleeder resistor R

. At this time, when the power voltage is in the range of 2 V to 16 V*

. The

low-voltage, lock out UVL1 operates and accordingly the OUT voltage, that is, the gate voltage of the
power MOSFET, is fixed at 1.3 V or a lower value, resulting in the power MOSFET remaining in the OFF
state.

When the power supply voltage reaches 16 V, UVL1 of this IC is reset and the reference voltage (Vref)
generating part turns ON. However, until Vref becomes 4.7 V, the low-voltage, lock out UVL2 operates to
keep the OUT terminal voltage low. After Vref terminal voltage becomes 4.7 V or higher, OUT terminal
outputs a PWM pulse.

Note: 1. The value is for the HA17384S/H.

The value is 8.4 V for the HA17385H.

Generation of Triangular Wave and PWM Pulse

After the output of the Vref, each blocks begins to operate. The triangular wave is generated on the R

terminal. For PWM pulses, the triangular wave rise time is taken as the variable on-duty on-time. The
triangular wave fall time is taken as the dead-band time. The initial rise of the triangular wave starts from 0
V, and to prevent a large on-duty at this time, the initial PWM pulse is masked and not output. PWM
pulses are outputted after the second triangular wave. The above operation is enabled by the charge energy
which is charged through the bleeder resistor R

into the capacitor C

of V

Stationary Operation

PWM pulses are outputted after the second wave of the triangular wave and stationary operation as the
switching power supply starts.

By switching operation from ON/OFF to OFF/ON in the switching device (power MOSFET), the
transformer converts the voltage. The power supply of IC V

is fed by the back-up winding of the

transformer.

In the current mode of the IC, the current in the switcing device is always monitored by a source resistor
R

. Then the current limiter level is varied according to the error voltage (COMP terminal voltage) for

PWM control. One third of the error voltage level, which is divided by resistors "2R" and "R" in the IC, is
used to sense the current (R = 25 k

Two diodes between the error output and the 2R-R circuit act only as a DC level shifter. Actually, these
diodes are connected between the 2R-R circuit and GND, and, the current sensing comparator and GND,
respectively. Therefore, these blocks operate 1.4 V higher than the GND level. Accordingly, the error of the
current sensing level caused by the switching noise on the GND voltage level is eliminated. The zener
diode of 1 V symbolically indicates that the maximum sensing voltage level of the CS terminal is 1 V.

HA17384SPS/SRP, HA17384HPS/HRP, HA17385HPS/HRP

Power OFF

At power OFF, the input voltage of the transformer gradually decreases and then V

of IC also decreases

according to the input voltage. When V

becomes lower than 10 V*

or Vref becomes lower than 4.7 V,

UVL1 (UVL2) operates again and the PWM pulse stops.

Note: 2. The value is for the HA17384S/H.

The value is 7.6 V for the HA17385H.

Commercial AC voltage

Power switch

Line filter

Rectifier
bridge diode

DC
output

Floating
ground

Power MOSFET
ex. 2SK1567

SBD

ex. HRP24

OVP input

(Ex: from photocoupler)

20k

3.6k

100

200V

1000

10V

10k

220k
1/4W

50V

0.1

HRP32

Vref

OUT

GND

COMP

HA17384H,
HA17385H

1
2W

100p

150k

330p

3300p

Figure 2 Mounting Circut Diagram for Operation Expression

HA17384SPS/SRP, HA17384HPS/HRP, HA17385HPS/HRP

COMP

COMP terminal
(Error output)

PWM pulse

Latch setting pulse
(Implemented in triagular
wave oscillator)

Latch setting
pulse

COMP

Error voltage

Current sensing
level

1 V

CS terminal

2 R

latch

Figure 3 Operation Diagram of Current Sensing Part

Point:

Current Sense Comparator

Threshold Voltage V

(V)

Error Amplifier Output Voltage Vcomp (V)

Light load

Heavy load

1) At maximum rated load, the setting should be made to give
approximately 90% of area A below.
2) When the OVP latch is operated, the setting should be made
in area B or C.

1.0

0.8

0.6

0.4

0.2

0.0

1.4V

4.4V

7.5V

A : Stationary operation / PWM
(Current-mode operation)
B : Current limit operation / Max duty cycle
C : No sensitivity area / No PWM output

Figure 4 Current Sense Characteristics

HA17384SPS/SRP, HA17384HPS/HRP, HA17385HPS/HRP

Features and Theory of Current Mode Control

Features of Current Mode Control

Switch element current detection is performed every cycle, giving a high feedback response speed.

Operation with a constant transformer winding current gives a highly stable output voltage (with
excellent line regulation characteristics, in particular).

Suitable for flyback transformer use.

External synchronous operation is easily achieved. (This feature, for example, is applicable to
synchronization with a forizontal synchronizing signal of CRT monitor.)

Theory of Current Mode Control

In current mode control, a PWM pulse is generated not by comparing an error voltage with a triangular
wave voltage in the voltage mode, but by changing the current limiter level in accordance with the error
voltage (COMP terminal in this IC, that is,output of the error amplifier output) which is obtained by
constantly monitoring the current of the switching device (power MOSFET) using source resistor R

One of the features of current mode control is that the current limited operates in all cycles of PWM as
described by the above theory.

In voltage mode, only one feedback loop is made by an output voltage. In current mode, on the other hand,
two loops are used. One is an output voltage loop and the other is a loop of the switching device current
itself. The current of the switching device can be controlled switch high speed. In current mode control,
the current in the transformer winding is kept constant, resulting in high stability. An important
consequence is that the line regulation in terms of total characteristics is better than that in voltage mode.

Transformar

input

Current sense
comparator

Error amplifier

DC
output

COMP

Vref

OSC

Flip flop

Figure 5 Block Diagram of Current Mode Switching Power Spply

HA17384SPS/SRP, HA17384HPS/HRP, HA17385HPS/HRP

Main Characteristics

Operating Current I

(mA)

Operating Current I

(mA)

Operating Current I

(mA)

Power supply voltage V

(V)

Ambient temperature Ta (

Operating Current vs. Ambient Temperature

Standby Current/Latch Current vs. Supply Voltage

Exploded diagram of the small current part from the above figure

(HA17384S/H)

Power supply voltage V

(V)

Standby Current/Latch Current vs. Supply Voltage

Exploded diagram of the small current part from the above figure

(HA17385H)

Power supply voltage V

(V)

Power supply voltage V

(V)

Ambient temperature Ta (

2.0

1.5

1.0

0.5

Ta = 25

fosc = 52kHz

= 3300pF

= 10k

Ta = 25

fosc = 52kHz

= 3300pF

= 10k

Ta = 25

2.0

1.5

1.0

0.5

400

300

200

100

Supply Current vs. Supply Voltage (HA17384S/H)

Supply Current vs. Supply Voltage (HA17385H)

Operating Current I

(mA)

Operating Current I

(mA)

Standby

Latch Current (

Standby Current/Latch Current vs. Ambient Temperature

Latch current

(HA17384H)

Latch current

(HA17384H)

Latch current

Stanby current

105

= 15V

fosc = 52kHz

= 3300pF

= 10k

Latch current
V

= 15V (HA17384H)

= 8.5V (HA17385H)

Latch current

HA17384SPS/SRP, HA17384HPS/HRP, HA17385HPS/HRP

Ambient temperature Ta (

Supply voltage V

(V)

Output current of Vref terminal (mA)

terminal voltage V

(V)

UVL Threshold Voltage vs. Ambient Temperature

Line Regulation Characteristics of Reference Voltage

Load Regulation Characteristics of Reference Voltage

Reference Voltage vs. Ambient Temperature

Discharge Current vs. R

Terminal Voltage

Discharge Current vs. Ambient Temperature

UVL voltage (V)

Reference voltage Vref (V)

discharge current I

(mA)

5.2

5.1

5.0

4.9

4.8

6.0

5.5

5.0

4.5

4.0

100

Ta = 25

= 15V

= 3300pF

= 10k

9.5

9.0

8.5

8.0

7.5

5.2

5.1

5.0

4.9

4.8

Ta = 25

= 15V

9.5

9.0

8.5

8.0

7.5

discharge current Isink

(mA)

105

HA17385H

HA17384S/H

= 3300pF

= 10k

= 3300pF

= 10k

= 15V

=15 V

Ta = 25

= 10V or more (HA17384S/H)

= 7.6V or more (HA17385H)

Vref short
protection
operates

Measured when
R

terminal voltage

is externally supplied

Minimum voltage of
triangular wave

Maximum voltage of
triangular wave

Measured when R

terminal voltage of 2 V is
externally supplied

HA17384SPS/SRP, HA17384HPS/HRP, HA17385HPS/HRP

Oscillation frequency fosc (kHz)

Timing resistance R

(

)

500

200

100

500

10k

20k

50k 100k 200k

Ta = 25¡C

= 15V

2200pF

4700pF

0.01

0.022

0.047

1000pF

470pF

Figure 7 Oscillation Frequency vs. Timing Resistance

Triangular wave

PWM maximum ON pulse

In the case of small C

and large R

(ex. C

= 3300pF, R

= 10k

)

Du max = 95%
fosc = 52kHz

Triangular wave

PWM maximum ON pulse

In the case of large C

and small R

(ex. C

= 0.033

F, R

= 680

)

Du max = 40%
fosc = 52kHz

Case 1.
Setting large maximum duty cycle.

Case 2.
Setting small maximum duty cycle.

Figure 8 Relationship Between Triangular Wave and Maximum ON Duty of PWM Pulse

HA17384SPS/SRP, HA17384HPS/HRP, HA17385HPS/HRP

Oscillation Frequency fosc (kHz)

Ambient Temperature Ta (

Ambient temperature Ta (

Operating Current I

(mA)

Maximum ON Duty Du max (%)

Output load capacitance C

(pF)

Oscillation Frequency vs. Ambient Temperature

Operating Current vs. Maximum ON Duty

Rise/Fall Time of Output Pulse vs. Load Capacitance

Rise/Fall Time of Output Pulse vs. Ambient Temperature

Rise/Fall Time (ns)

Current sensing level V

(V)

(UVL1)

Vref
(UVL2)

PWM
OUTPUT

Condition
description

Standby
state

IC is in
the ON
state and
output is
fixed to
LO.

Available
to
output

Current Sensing Level vs. Ambient Temperature

Relationship Between Low Voltage Malfunction

Protection and PWM Output

Operation
state

Standby
state

100

= 15V

fosc=50kHz

fosc=300kHz

= 0V

250

1000

2000

3000

Fall Time tf

200

150

100

= 15V

= 0V

Ta = 25

= 3300pF

= 10k

4000

250

200

150

100

1.25

1.00

0.75

0.50

0.25

= 15V

= 1000pF

= 3300pF

= 10k

Dumax = 95%

= 15V

= 0V

= 3300pF

= 10k

= 15V

= 0V

Rise time tr

= 1000pF

105

= 0.033

= 680

Dumax = 40%

Ta=25

= 1000pF

Rise time t

Fall Time t

Measured when COMP terminal
voltage is externally supplied

HA17384SPS/SRP, HA17384HPS/HRP, HA17385HPS/HRP

Triangular wave

PWM maximum
ON pulse

Dumax is the ratio of
maximum ON time of
PWM to one cycle time.

In the above case,
Dumax = 95%

Calculation of operation parameters

1. Maximum ON duty Du max (Refer to the right figure.)

Du max =

1 + 1.78

In 1 +

190

440

(

)

+ 440

190

0.56 (1/Du max

= 1.78

Du max

fosc

max

THCS

fosc =

0.56 + In 1 +

190

(

)

{

}

2. Oscillation frequency fosc

From the above two equations, the following two equations are
obtained.

3. Equalization to device R

from Du max

(e = 2.71828.base of natural logarithm)

4. Equation to device C

from fosc and R

5. Operating current I

= I

+ Isink

Du max) + Ciss

fosc

providing that I

= 8.4mA Typ (Supply current when oscillation in IC stops.)

Ciss is the input gate capacitance of the power MOSFET which is connected and V

the supply voltage of the IC.

Note that the actual value may differ from the calculated one because of the internal
delay in operation and input characteristics of the POWER MOS FET. Check the
value when mounting.
Additionally a small Dumax leads to a large supply current, even if the frequency is
not changed, and start up may become difficult. In such a case, the following
measure is recommended.

Example 1: Calculation when R

= 10k

and C

= 3300pF

fosc = 52kHz, Du max = 95%, I

= 9.7mA

Example 2: Calculation for 50% of Du max and 200 kHz of fosc
R

= 693

, C

= 6360pF, I

= 12.5mA

(1) For an AC/DC converter, a small bleeder resistance is required.

(2) The large capacitance between Vref and GND is required.

(3) Use a large Dumax with a triangular wave and raise the current limit of the
switching device to around the maximum value (1.0V Typ).

The current limit is expressed as

440

However, Ciss = 1000pF, V

= 18V

Figure 11 Calculation of Operation Parameters

HA17384SPS/SRP, HA17384HPS/HRP, HA17385HPS/HRP

Application Circuit Example (1)

Notes:

Snubber circuit
example

470p

1kV

FRD
DFG1C8

1. : PRIMARY GND, : SECONDARY GND.
2. Check the wiring direction of the transformer coil.
3. Insert a snubber circuit if necessary.
4. OVP function is not included in HA17384SPS/SRP.

Commercial
AC 100V

Rectifier bridge diode

Line filter

Transformer specification
example
EI-22 type core
(H7C18

06Z)

Gap length
lg = 0.3mm

Transformer coil example
P: 0.5¿80T/570

S: 0.5¿16T Bifiler/22

B: 0.2¿44T/170

(Opetation Theory)
Because this circuit is a flyback type, the voltages in the
primary (P), secondary (s) coils of the transformer and
backup (B) coil are proportional to each other. Using this,
the output voltage of the backup coil (V

of IC) is controlled

at constant 16.4V. (The voltage of the point divided by
resistors of 20k

and 3.6k

is 2.5V).

20k

3.6k

100

200V

1000

10V

10k

220k
1/4W

50V

16.4V

0.1

HRP32

DC 5V, 3A
OUTPUT

Vref

OUT

GND

COMP

HA17384H,
HA17385H

2SK1567

SBD
HRP24

1
2W

100p

150k

470p

3300p

141V

10k

2SA1029

HA17431

10k

47k

Figure 12 Primary Voltage Sensing Flyback Converter

HA17384SPS/SRP, HA17384HPS/HRP, HA17385HPS/HRP

Application Circuit Example (2)

Photocoupler
(for output control)

Commercial
AC 100V

Rectifier bridge diode

When the error amplifier is used

Line filter

Transformer specification
example
EI-22 type core
(H7C18

06Z)

Gap length
lg = 0.3mm

Transformer coil example
P: 0.5¿80T/570

S: 0.5¿16T Bifiler/22

B: 0.2¿44T/170

(Operation Theory)
On the secondary side (S) of the flyback converter,
error amplification is carried out by a shunt
regulator and photocoupler.
The voltage of the backup coil (B) is not monitored,
which differs from the application example (1).

In addition, OVP operates on the secondary side
(S) using a photocoupler.

Refer to the application example (1) for the other
notes.

When the error
amplifier is not used

Bleeder resistor
(adjuster according
to the rating of the
Photocoupler)

100

200V

1000

10V

10k

220k
1/4W

50V

16.4V

141V

0.1

4.7k

HRP32

DC
5V, 3A
OUTPUT

Vref

OUT

GND

COMP

HA17384H,
HA17385H

HA17431

2SK1567

SBD
HRP24

1.8k

4.7k

1
2W

100p

150k

470p

3300p

330

3.3

3.3k

Vref

OUT

GND

0.8mA

COMP

OVP input

47k

HA17431

2SA1029

10k

Figure 13 Secondary Voltage Sensing Flyback Converter

HA17384SPS/SRP, HA17384HPS/HRP, HA17385HPS/HRP

Application Examples for Fuller Exploitation of Power Supply Functions

A number of application examples are briefly described below.

1. Soft start

A soft start is a start method in which the PWM pulse width is gradually increased when the power
supply is activated. This prevents the stress on the transformer and switch element caused by a rapid
increase in the PWM pulse width, and also prevents overshoot when the secondary-side output voltage
rises. The circuit diagram is shown in figure 14.

800

A typ

Vref
5V

(3V)

(4.4V)

(3.7V)

(5V)

REF

2.5V

IC internal circuit
(around error amp.)

External circuit
(only partially shown)

To power supply
detection
comparator

(1V)

COMP

Figure 14 Circuit Diagram for Soft Start

Operation: In this circuit, error amp output source current I

(800

A typ.) gradually raises the switch

element current detection level, using a voltage slope that charges soft start capacitance C

. When the

voltage at each node is at the value shown in parentheses in the figure, the soft start ends. The soft start
time is thus given by the following formula:

= (3.7 V/800

4.62 C

(ms)

unit:

External parts other than C

operate as follows:

Diode D1

: Current detection level shift and current reverse-flow prevention.

Diode D2

: Together with diode D

in the IC, C

charge drawing when power supply falls.

Resistance R

: For C

charge-up at end of soft start. (Use a high resistance of the order of several

hundred k

Note:

During a soft start, since PWM pulses are not output for a while after the IC starts operating, there
is a lack of energy during this time, and intermittent mode may be entered. In this case, the
capacitance between Vref and GND should be increased to around 4.7

F to 10

HA17384SPS/SRP, HA17384HPS/HRP, HA17385HPS/HRP

2. OVP latch output overvoltage protection (the HA17384H and HA17385H only)

The OVP latch is incorporated in the error amp input pin (FB). If the FB pin is pulled up to 7.0 V typ.
just once when the power supply enters any kind of error state, IC operation can be halted and held as it
is (latched). To reset the latch, drop the IC's supply voltage to 7.0 V typ. or below momentarily.

An OVP latch application example is shown in figure 15.

47k

2.5V

Inside IC

OVP comparator

Error amplifier

OVP

7.0V

COMP

10k

HA17431
(Vref

2.5V)

2SA1029

10k

External circuit
(only partially shown)

Figure 15 Example of OVP Latch Application Circuit

This circuit protects the system by causing latch operation in the event of an overload or load short. In
the steady state, the error amp input/output pins operate at 2.5 V typ., but if the load becomes heavy the
FB pin level drops and the COMP pin level rises. As shown in the figure, this is detected by the
HA17431 shunt regulator, and the FB pin level is pulled up, operating the OVP latch.

The operation parameters are as follows:

COMP pin voltage detection level: Vth = (R

+ R

) / R

2.5 V

HA17384SPS/SRP, HA17384HPS/HRP, HA17385HPS/HRP

Notice for Use

1. OVP Latch Block

Case

When DC power is applied directly as the power supply of the HA17384H, HA17385H, without using
the transformer backup coil. Also, when high-frequency noise is superimposed on the V

pin.

Problem

The IC may not be turn on in the case of a circuit in which V

rises quickly (10 V/100

s or faster),

such as that shown in figure 16. Also, the OVP latch may operate even though the FB pin is normally at
V

OVP

or below after the IC is activated.

Reason

Because of the IC circuit configuration, the timer latch block operates first.

Remedy (counter measure)

Take remedial action such as configuring a time constant circuit (R

, C

) as shown in figure 17, to keep

the V

rise speed below 10 V/100

s. Also, if there is marked high-frequency noise on the V

pin, a

noise cancellation capacitor (C

) with the best possible high-frequency characteristics (such as a

ceramic capacitor) should be inserted between the V

pin and GND, and close to the V

pin.

When configuring an IC power supply with an activation resistance and backup winding, such as an
AC/DC converter, the rise of V

will normally be around 1 V/100

s, and there is no risk of this problem

occurring, but careful attention must be paid to high-frequency noise.

Also, this phenomenon is not occuring to the HA17384S, because OVP function is not built-in.

Output

Input

GND

Feedback

HA17384

Series

Figure 16 Example of Circuit with Fast V

Rise Time

HA17384SPS/SRP, HA17384HPS/HRP, HA17385HPS/HRP

Output

Input

Time constant

circuit

Feedback

HA17384

Series

18V

GND

Figure 17 Sample Remedial Circuit

2. Externally Synchronized Operation

Case

When, with a power supply using the HA17384S/H or HA17385H, externally synchronized operation is
performed by applying an external syncronous signal to the R

pin (pin 4).

Problem

Synchronized operation may not be possible if the amplitude of the external syncronous signal is too
large.

Reason

The R

pin falls to a potential lower than the ground.

Remedy (counter measure)

In this case, clamping is necessary using a diode with as small a V

value as possible, such as a schottky

barrier diode, as shown in figure 18.

Vref

0.01

HA17384

Series

External

synchronous

signal

Figure 18 Sample Remedial Circuit

HA17384SPS/SRP, HA17384HPS/HRP, HA17385HPS/HRP

Cautions

1. Hitachi neither warrants nor grants licenses of any rights of Hitachi's or any third party's patent,

copyright, trademark, or other intellectual property rights for information contained in this document.
Hitachi bears no responsibility for problems that may arise with third party's rights, including
intellectual property rights, in connection with use of the information contained in this document.

2. Products and product specifications may be subject to change without notice. Confirm that you have

received the latest product standards or specifications before final design, purchase or use.

3. Hitachi makes every attempt to ensure that its products are of high quality and reliability. However,

contact Hitachi's sales office before using the product in an application that demands especially high
quality and reliability or where its failure or malfunction may directly threaten human life or cause risk
of bodily injury, such as aerospace, aeronautics, nuclear power, combustion control, transportation,
traffic, safety equipment or medical equipment for life support.

4. Design your application so that the product is used within the ranges guaranteed by Hitachi particularly

for maximum rating, operating supply voltage range, heat radiation characteristics, installation
conditions and other characteristics. Hitachi bears no responsibility for failure or damage when used
beyond the guaranteed ranges. Even within the guaranteed ranges, consider normally foreseeable
failure rates or failure modes in semiconductor devices and employ systemic measures such as fail-
safes, so that the equipment incorporating Hitachi product does not cause bodily injury, fire or other
consequential damage due to operation of the Hitachi product.

5. This product is not designed to be radiation resistant.

6. No one is permitted to reproduce or duplicate, in any form, the whole or part of this document without

written approval from Hitachi.

7. Contact Hitachi's sales office for any questions regarding this document or Hitachi semiconductor

products.

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For further information write to:

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