SiP2800/01/02/03/04/05

Vishay Siliconix

New Product

Document Number: 72660

S-41623--Rev.C, 30-Aug-04

www.vishay.com

Low Power Consumption Current Mode Controller

FEATURES

Pin-for-Pin Compatible with UCC280X Controllers

Enhanced Performance UC284X for New Designs

100-

A Typical Start-Up Current

500-

A Typical Operating Current

Internal Soft Start at Power-On and After Fault

100-ns Internal Leading Edge Blanking

APPLICATIONS

Efficiency-Enhanced DC/DC Converter Modules

Low Quiescent Current Standby Power Supplies

Offline (AC/DC) Power Supplies

Universal Input Power Supplies

Buck, Boost, and Buck-Boost Converters

DESCRIPTION

The SiP280X family includes six high-speed, low power

consumption, BiCMOS Current Mode Controllers. These

integrated circuits contain all of the control and drive functions

required for off-line and dc-to-dc current-mode switching

power supplies. Their advanced architecture enables the

implementation of full-featured designs with minimal external

parts count.

The SiP280X family controllers are available in both standard

and lead (Pb)-free, SO-8 and TSSOP-8 packages, and are

rated for operation over the industrial temperature range of

--40 to 85

Part Number

Maximum

Duty Cycle

Reference

Voltage

Turn-On

Threshold

Turn-Off

Threshold

SiP2800

100%

5 V

7.2 V

6.9 V

SiP2801

50%

5 V

9.4 V

7.4 V

SiP2802

100%

5 V

12.5 V

8.3 V

SiP2803

100%

4 V

4.1 V

3.6 V

SiP2804

50%

5 V

12.5 V

8.3 V

SiP2805

50%

4 V

4.1 V

3.6 V

TYPICAL APPLICATION CIRCUIT

REF

GND

OUT

+48 V

GND

COMP

SiP2801

12 V/3 A

Flyback Converter for Point of Load Application

SiP2800/01/02/03/04/05

Vishay Siliconix

New Product

www.vishay.com

Document Number: 72660

S-41623--Rev.C, 30-Aug-04

ABSOLUTE MAXIMUM RATINGS

12 V

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

FB, Comp, CS

--0.3 V to 6 V

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Power Disispation SO-8

1 W

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Power Disispation TSSOP-8

830 mW

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

StorageTemperature

--55 to 150

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Currents are positive into, negative out of the specificed terminal.

Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation

of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating

conditions for extended periods may affect device reliability.

RECOMMENDED OPERATING RANGE

Input Voltage SiP2803/5

5 to 11 V

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Input Voltage SiP2800/1/2/4

6 to 11 V

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Operating Temperature Range

--40 to 85

. . . . . . . . . . . . . . . . . . . . . . . . . . .

SPECIFICATIONS

Test Conditions Unless Specified

Limits

Parameter

Symbol

= 10 V, R

= 100 k

, C

= 330 pF

REF

= 0.1

F, --40

C < T

< 85

Min

Typ

Max

Unit

Reference

LOAD

= 0 2 mA T

= 25

�

SiP2800/1/2/4

4.925

5.000

5.075

Reference Voltage

REF

LOAD

= 0.2 mA, T

= 25

�

SiP2803/5

3.940

4.000

4.06

Reference Voltage

REF

SiP2800/1/2/4

4.88

5.00

5.10

SiP2803/5

3.90

4.00

4.08

Load Regulation

LOAD

0.2mA< I

LOAD

<5mA

Line Regulation

Vcc=10 V to Clamp , T

= 25

�

1.9

mV/V

Line Regulation

LINE

Vcc=10 V to Clamp

2.5

mV/V

Noise

NOISE

10 Hz < f < 10 kHz T

�

130

Short Circuit Current

10 Hz < f < 10 kHz, T

= 25

�

--5

--35

Oscillator

Frequency

OSC

SiP2800/1/2/4

kHz

Frequency

OSC

SiP2803/5

kHz

Temperature Stability

2.5

Amplitude

P--P

2.25

2.40

2.55

Peak Voltage

2.45

Error Amplifier

Input Voltage

COMP = 2.5 V

SiP2800/1/2/4

2.44

2.50

2.56

Input Voltage

COMP = 2.0 V

SiP2803/5

1.95

2.00

2.05

Input Bias Current

BIAS1

--1

Open Loop Gain

COMP Sink Current

SINK

FB = 2.7 V, COM P= 1.1 V

0.3

3.5

COMP Source Current

SOURCE

FB = 1.8 V, COMP = V

REF

-- 1.2 V

--0.2

--0.5

--0.8

Gain Bandwidth

MHz

PWM and Overcurrent Comparator

Maximum Duty Cycle

MAX

SiP2800/2/3

100

Maximum Duty Cycle

MAX

SiP2801/4/5

Minimum Duty Cycle

MIN

COMP = 0 V

Gain

0 < V

< 0.8 V

1.2

1.65

1.9

V/V

Max. Input Signal

MAX

COMP = 5 V

0.9

1.0

1.1

Input Bias Current 2

BIAS2

--200

200

SiP2800/01/02/03/04/05

Vishay Siliconix

New Product

Document Number: 72660

S-41623--Rev.C, 30-Aug-04

www.vishay.com

SPECIFICATIONS

Limits

Test Conditions Unless Specified

= 10 V, R

= 100 k

, C

= 330 pF

REF

= 0.1

F, --40

C < T

< 85

Parameter

Unit

Max

Typ

Min

Test Conditions Unless Specified

= 10 V, R

= 100 k

, C

= 330 pF

REF

= 0.1

F, --40

C < T

< 85

Symbol

PWM and Overcurrent Comparator

COMP to CS Offset

CS = 0 V

0.45

0.90

1.35

CS Pin Blanking Time

100

150

Overcurrent Comparator Fault

Threshold

1.47

1.73

Output

I = 20 mA

All Parts

0.1

0.40

I = 200 mA

All Parts

0.35

0.90

I = 50 mA, V

= 5 V

SiP2803/5

0.15

0.40

Output Voltage

I = 20 mA, V

= 0 V

All Parts

0.70

1.20

I = --20 mA

All Parts

0.15

0.40

-- V

I = --200 mA

All Parts

1.00

1.90

I = --50 mA, V

= 5 V

SiP2803/5

0.40

0.90

Rise Time

CL= 1 nF

Fall Time

CL= 1 nF

Undervoltage Lockout

SiP2800

6.6

7.2

7.8

Start Threshold

START

SiP2801

8.6

9.4

10.2

Start Threshold

START

SiP2802/4

11.5

12.5

13.5

SiP2803/5

3.7

4.1

4.5

SiP2800

6.3

6.9

7.5

Stop Threshold

STOP

SiP2801

6.8

7.4

8.0

Stop Threshold

STOP

SiP2802/4

7.6

8.3

9.0

SiP2803/5

3.2

3.6

4.0

SiP2800

0.05

0.30

0.48

Start to Stop Hysteresis

HYS

SiP2801

1.5

2.0

2.4

Start to Stop Hysteresis

HYS

SiP2802/4

3.0

4.2

5.1

SiP2803/5

0.2

0.5

0.8

Soft-Start

COMP Rise Time

FB = 1.8 V, Rise from 0.5 V to V

REF

--1 V

Overall

Start-up Current

START

Vcc < Start Threshold

0.1

0.2

Operating Supply Current

FB = 0 V, CS = 0 V

0.5

1.0

Vcc Internal Zener Voltage

= 10 mA

12.0

13.5

15.0

Vcc Internal Zener Voltage Minus

Start Threshold Voltage

--V

START

SiP2802/04

0.5

1.0

Notes

The algebraic convention whereby the most negative value is a minimum and the most positive a maximum (--40

to 85

C).

Typical values are for DESIGN AID ONLY, not guaranteed nor subject to production testing and are measured at V

= 12 V unless otherwise noted.

Gain is defined by A =

COMP

CS ,

0 V

0.8 V.

Start, Stop, and Zener voltages track each other.

SiP2800/01/02/03/04/05

Vishay Siliconix

New Product

www.vishay.com

Document Number: 72660

S-41623--Rev.C, 30-Aug-04

TYPICAL CHARACTERISTICS

--30

10000

Error Amplifier Gain and Phase vs. Frequency

Frequency (kHz)

i
n

)

100

150

200

250

300

350

400

450

500

100 200 300 400 500 600 700 800 900 1000

= 100 k

Oscillator Dead Time vs. C

(pf)

SiP2800/01/02/04

Oscillator Frequency vs. R

and C

)

s
c
illa

t
o
r

r
equenc

(
k
H

z
)

ead

T
i
me

(
n
S

)

0.7

0.8

0.9

1.0

1.1

1.2

1.3

--50

--25

100

125

150

CS = 0 V

COMP to CS Offset Voltage vs. Temperature

Temperature (

SiP2803/05

Oscillator Frequency vs. R

and C

)

s
c
illa

t
o
r

r
equenc

(
k
H

z
)

f
fs

e
t
(
V

)

60
50

20
10

--10

--20

1000

135

--45

has

(

)

= 100 pF

1000

100

1000

100

1000

= 200 pF

= 330 pF

= 1000 pF

= 100 pF

= 200 pF

= 330 pF

= 1000 pF

SiP2803/05

SiP2800/01/02/04

Phase

Gain

SiP2800/01/02/03/04/05

Vishay Siliconix

New Product

Document Number: 72660

S-41623--Rev.C, 30-Aug-04

www.vishay.com

PIN CONFIGURATION

COMP

REF

OUT

GND

SOIC-8

Top View

COMP

1
2
3
4

8
7
6
5

REF
V

OUT
GND

TSSOP-8

Top View

ORDERING INFORMATION

SOIC-8

TSSOP-8

Part Number

Lead (Pb)-Free

Part Number

Marking Temperature

Part Number

Lead (Pb)-Free

Part Number

Marking Temperature

SiP2800DY-T1

SiP2800DY-T1--E3

2800

SiP2800DQ-T1

SiP2800DQ-T1--E3

2800

SiP2801DY-T1

SiP2801DY-T1--E3

2801

SiP2801DQ-T1

SiP2801DQ-T1--E3

2801

SiP2802DY-T1

SiP2802DY-T1--E3

2802

40 to 85

SiP2802DQ-T1

SiP2802DQ-T1--E3

2802

40 to 85

SiP2803DY-T1

SiP2803DY-T1--E3

2803

--40 to 85

SiP2803DQ-T1

SiP2803DQ-T1--E3

2803

--40 to 85

SiP2804DY-T1

SiP2804DY-T1--E3

2804

SiP2804DQ-T1

SiP2804DQ-T1--E3

2804

SiP2805DY-T1

SiP2805DY-T1--E3

2805

SiP2805DQ-T1

SiP2805DQ-T1--E3

2805

Additional voltage options are available.

PIN DESCRIPTION

Pin Number

Name

Function

COMP

Output of the Voltage Error Amplifier, and the inverting input to the PWM's Current Sense Comparator

Inverting input of the Voltage Error Amplifier

Non-inverting input of the PWM Current Sense Comparator, and inverting input of the Overcurrent Fault Comparator

(both comparators are fed from the output of the internal 100-ns Leading Edge Blanking circuit)

Connection for the PWM Oscillator's timing resistor and timing capacitor

GND

Ground Pin.

OUT

PWM Output Signal (capable of driving

750 mA into the gate of an external MOSFET power switch)

Positive supply voltage for the IC

REF

IC Reference Voltage

SiP2800/01/02/03/04/05

Vishay Siliconix

New Product

www.vishay.com

Document Number: 72660

S-41623--Rev.C, 30-Aug-04

DETAILED PIN DESCRIPTION

COMP
COMP is the output of the Voltage Error Amplifier (VEA). The

VEA is a low output impedance operational amplifier, providing

the input to the PWM cycle-by-cycle current limit comparator.

As the SiP280X series of parts use a true operational amplifier

for the VEA, the COMP terminal can both source and sink

current. To add flexibility to these parts, the VEA is internally

current limited, which allows OUT to be forced to zero duty

cycle by taking the COMP pin to GND.

The voltage on COMP is passed through an internal diode to

develop an offset voltage of approximately 0.6 V, and then

through a resistive divider with a gain of 0.606-V/V, before

being presented to the control input of the cycle-by-cycle

current limit comparator. Clamping the COMP pin to less than

the diode's forward voltage (i.e.,

0.5 V) will command the

current loop to deliver 0 A, by holding the control input of the

cycle-by-cycle current comparator at 0 V. Similarly, the current

loop will command the maximum inductor current on each

cycle when COMP is at 2.25 V or greater, which drives the

control input of the cycle-by-cycle current comparator to 1 V

(since [2.25 V -- 0.6 V]

�

0.606 V/V = 1 V).

The SiP280X series additionally features a built-in soft-start

function, which functions by clamping the output level of the

VEA to an internally generated voltage. This clamp will hold

COMP at a low voltage (V

COMP

0 V) until V

and V

REF

are

at their proper levels. When these levels are appropriate for

circuit operation, the internal voltage will begin rising, at the

rate of 1 V/ms. This rising clamp level allows the voltage on the

COMP pin to rise, which in turn allows the voltage at the control

input of the cycle-by-cycle current comparator to increase. The

maximum soft-start interval occurs under conditions requiring

full duty cycle (50% or 100%, depending upon the part type),

and is given by the time required for the voltage on the

cycle-by-cycle current comparator's control input to reach 1 V.

Since 1 V at the control input to the comparator requires that

the COMP pin be at 2.25 V, the maximum soft-start interval is

approximately 2.25 ms.
CS
Input to both the cycle-by-cycle and overcurrent fault current

sense comparators. The cycle-by-cycle current limit

comparator is the mechanism by which the VEA's output

voltage commands the level of inductor or transformer current

during a given "on" interval, thereby regulating the overall

circuit's output. This comparator forms the inner loop of the two

loops used in current-mode regulation.

The overcurrent comparator has a trip threshold that is 50%

higher than that of the cycle-by-cycle comparator. Under

normal operating conditions, this comparator will not trip: its

purpose is to provide enhanced protection of the power path

components during severe faults (e.g., a short circuit). If the

overcurrent comparator is tripped by a fault condition, it will

command the SiP280X to do a "full-cycle restart." During this

restart, the power supply will be quickly driven to the "off" state,

and will be required to wait for five milliseconds (typical) before

restarting. When the supply does restart, it will do so using the

built-in soft-start function of the SiP280X.

The SiP280X family incorporates internal leading-edge

blanking on the CS pin, to keep any spurious voltages on the

CS pin from reaching the comparator inputs during the 100-ns

interval immediately following the rising edge on OUT (for

example, voltages due to capacitive charging currents).

Because of this internal leading-edge blanking, many

applications require no external RC filter on the CS input.

Compared to circuits requiring the use of an external RC filter

circuit, leading-edge blanking provides a shorter effective CS

to OUT propagation delay.

FB is the inverting input of the VEA. Internally compared

against V

REF

/2 appearing on the VEA's non-inverting input. To

avoid stability problems, keep lead lengths to FB as short as

possible, and use good layout practices to minimize the stray

capacitances of components connected to this pin.

GND

The GND pin is both the reference ground and the power

ground for this part.

OUT

OUT is the output of a high-current driver capable of peak

currents in excess of

750 mA. OUT is therefore well suited

to driving the gates of power MOSFETs. This pin is specifically

held low when V

is below the SiP280X's UVLO threshold, to

ensure a predictable system turn-on. Since the OUT pin is

internally connected to a low impedance CMOS buffer, it is

capable of rapid rail-to-rail transitions. This output topology

also mitigates the effects of undershoot and overshoot. For

this reason, external Schottky clamp diodes are generally not

required on this pin.

RC is the oscillator frequency programming pin. F

OSC

is set by

the combination of R

and C

. The charging current for C

provided through R

, which is normally connected between

REF and the SiP280X RC pin. C

then connects from RC to

GND. Due to the high impedances encountered in low power

control circuits, this connection must be a short and quiet

return to GND (preferably by means of a dedicated signal

trace, separated from all other circuit functions).

The oscillator frequency for the SiP280X family of parts is

approximated by the following formulas:

For the SiP2800, SiP2801, SiP2802, and SiP2804:

OSC

(1.5)/R

For the SiP2803 and SiP2805:

OSC

(1.0)/R

Here R

is in ohms and C

is in farads.

More accurate formulas for F

OSC

are:

For the SiP2800, SiP2801, SiP2802 and SiP2804:

OSC

= 1/{[(C

+ C

STRAY

) x R

x 0.652] + [(C

+ C

STRAY

)

x R

DISCH

x 2.53] + T

DELAY

}

SiP2800/01/02/03/04/05

Vishay Siliconix

New Product

Document Number: 72660

S-41623--Rev.C, 30-Aug-04

www.vishay.com

For the SiP2803 and SiP2805:

OSC

= 1/{[(C

+ C

STRAY

) x R

x 0.93] + [(C

+ C

STRAY

) x

DISCH

x 2.53] + T

DELAY

}

Here R

is in ohms and C

is in farads, R

DISCH

is the value of

the resistor through which C

is discharged (normally an

on-chip 130-

resistor, unless the circuit is configured with

additional external discharge-path resistance), and t

DELAY

an inherent internal comparator delay time of 100 ns. The

capacitance associated with the RC pin is approximately

7.5 pF, and should be included as a part of C

STRAY

Note that the SiP2801, SiP2804, and SiP2805 have an internal

toggle flip-flop at the output of the oscillator, to ensure that the

output duty cycle never exceeds 50%. This divides the

frequency appearing at the OUT pin to one-half of the oscillator

frequency for these three parts.

Values of R

below 10 k are not recommended. Low values of

cause high circuit operating currents, and very low values

will prevent the oscillator from properly discharging C

REF
The reference generator block of the Si280X provides an

accurate and stable 4.0 V or 5.0 V (depending upon part

number), which is available at this pin of the IC. This voltage

is also used internally for other functions on the IC. One of

these uses is as the logic power supply for high speed

switching logic on the IC; this, and stability concerns, make it

important to bypass V

REF

to GND with a good quality 0.1-

ceramic capacitor, as close to the part as possible. An

electrolytic or tantalum capacitor may be used in addition to the

ceramic capacitor. When 1 V < V

< the UVLO threshold,

REF is pulled to ground through a 5-k

resistor. Hence, REF

can also be used as an output to indicate the part's V

status.

is the positive power connection for the SiP280X

controller IC, and should be the most positive terminal on the

part. In normal operation, V

is powered through a current

limiting resistor. The required start-up supply current will

generally be on the order of 100

A with V

below the UVLO

voltage of the SiP280X, and can remain at or below 500-

total supply current once the part starts switching. To prevent

the IC from being damaged by overvoltage conditions, each of

the SiP2800 family of parts has an internal clamp (effectively

a 12.5-V Zener diode) between V

and GND. If the part's V

pin is current-fed through an appropriate dropping resistor, the

pin will never exceed its rated voltage, nor will the the

device as a whole exceed its rated power dissipation. This

does require knowing what the operating current of the IC will

be, so that the value of the dropping resistor can be calculated.

A good estimate of the actual operating current (I

) may be

made by summing three components:

(a) Any external current loading on the V

or REF pins

(b) The operating current required by the IC itself, and
(c) The drive current (I

DRIVE

) required by the external

power switch.

Item (a) in the above list is a static dc value, and can generally

be calculated with good accuracy. Item (b) will increase with

operating frequency, but will be fixed for a given value of F

OSC

Item (c) is usually the dominant term in the calculation of I

as the power required to drive the external power switch will

typically increase as F

OUT

is increased. The most common

example of this is seen in driving the gate of a power MOSFET.

In such applications, the gate capacitances must be charged

once each switching cycle. This calculation is simplified by

using the gate charge term given by most MOSFET

manufacturers, allowing the use of the formula:

DRIVE

= F

OUT

�

of the chosen MOSFET.

A first approximation of the necessary dropping resistor value

is then given by:

R = [(Nominal V

SUPPLY

) � 12 V]/(Nominal I

)

Here R is in ohms and I

is in amperes.

The resistor limiting the current into the V

pin should be

selected such that I

CC(min)

equals the worst-case maximum

sum of the above currents, while holding I

CC(max)

to as low a

value above that number as practicable (for best overall

efficiency), and never more than 25 mA above that number (to

avoid exceeding the IC's internal clamp diode ratings). V

must be bypassed to GND with a good quality 0.1-

F ceramic

capacitor, as close to the part as possible. This will help avoid

problems created by high-frequency noise on the power

supply of the part. An electrolytic or tantalum capacitor may be

placed in parallel with the ceramic capacitor if more

capacitance is needed or desired.

Электронный компонент: SiP2804