KSI-L010-000
1
S494P
Pulse Width Modulation
Description
The S494 is a monolithic integrated circuit which includes all the necessary building blocks
for the design of pulse width modulate(PWM) switching power supplies, including push-pull,
bridge and series configuration. The device can operate at switching frequencies between
1KHz and 300KHz and output voltage up to 40V. The S494 is specified over an operating
temperature range of -40to85.
Features
Uncommitted output transistors capable of 200mA source or sink
Internal protection from double pulsing of out-puts with narrow pulse widths or with
supply voltages bellows specified limits
Easily synchronized to other circuits
Dead time control comparator
Output control selects single-ended or push-pull operation
Ordering
Information
Type NO.
Marking
Package Code
S494P
S494P
DIP-16
Outline Dimensions unit :
mm
S
S
e
e
m
m
i
i
c
c
o
o
n
n
d
d
u
u
c
c
t
t
o
o
r
r
PIN Connections
1. Non-INV Input
2. INV Input
3. Feed-Back
4. Dead-Time Control
5. C
T
6. R
T
7. GND
8. C1
9. E1
10. E2
11. C2
12. Vcc
13 Output Control
14. Ref Out
15. INV-Input
16. Non-INV Input
KSI-L010-000
2
S494P
Absolute Maximum Ratings
Ta=25
C
Characteristic Symbol
Ratings
Unit
supply voltage
V
CC
42 V
Voltage From Any Pin to Ground
(except pin 8 and pin 11)
V
IN
V
CC
+0.3 V
Output Collector Voltage
V
C1
, V
C2
42 V
Peak Collector Current
I
C1
, I
C2
250 mA
Power Dissipation
P
D
1500
mW
Operating Temperature
T
opr
-40 ~ 85
C
Storage Temperature
T
stg
-65 ~ 150
C
Recommended Operating Condition
Characteristic Symbol
Min.
Max.
Unit
supply voltage
V
CC
7 40 V
Voltage on Any Pin Except Pin
8 and 11(Referenced to Ground)
V
IN
-0.3
V
CC
+0.3 V
Output Voltage
V
C1
, V
C2
-0.3
40
V
Output Collector Current
I
C1
, I
C2
- 200 mA
Timing Capacitor
C
t
470 - PF
Timing Capacitor
C
t
- 10
Timing Resistor
R
t
1.8 500
Oscillator Frequency
f
OSC
1 300
KHz
Electrical Characteristics
Reference Section
Characteristic Symbol
Test
Condition Min.
Typ.
Max.
Unit
Reference Voltage
Vref
Iref = 1.0mA
4.75
5.00
5.25
V
Line Regulation
V
LINE
7V < Vcc < 40V
-
2
25
mV
Load Regulation
V
LOAD
1mA< I
REF
<10mA
- 1 15
mV
Temperature Coefficient
-
0
C
< Ta <70
C
- 0.01
0.03
%/
C
Oscillator Section
Characteristic Symbol
Test
Condition Min.
Typ.
Max.
Unit
Oscillator Frequency
f
OSC
C
t
=0.01 , R
t
=12
- 10 -
Oscillator Frequency Change
Over Operating Temperature
Range
f
SOC
C
t
=0.01 , R
t
=12
- - 2 %
KSI-L010-000
3
S494P
Dead Time Control Section
Characteristic Symbol
Test
Condition Min.
Typ.
Max.
Unit
Input Bias Current (Pin4)
I
IB(DT)
Vcc = 15V, 0V < V
4
< 5.25V
-
-2
-10
Max. Duty cycle, Each Output
DC
(Max)
Vcc = 15V, Pin4 = 0V,
Output Control Pin = Vref
43 - 45
%
Zero Duty
-
3
3.3
Input Threshold
Voltage
Max Duty
V
TH
-
0 - -
V
Error Amplifier Section
Characteristic Symbol
Test
Condition Min.
Typ.
Max.
Unit
Input Offset Voltage
V
IOS
V
3
= 2.5V
-
2
10
mV
Input Offset Current
I
IOS
V
3
= 2.5V
-
25
250
nA
Input Bias Current
I
IB
V
3
= 2.5V
-
0.2
1
Input Common Mode
voltage Range
V
ICR
7V V
CC
40V
-0.3 - V
CC
V
Large Signal Open Loop
Voltage Range
G
VO
0.5V V
3
3.5V
60 74 - dB
Unity Gain Band width
f
C
-
- 650 -
PWM Comparator Section (Pin3)
Characteristic Symbol
Test
Condition Min.
Typ.
Max.
Unit
Inhibit Threshold Voltage
V
THI
Zero duty cycle
-
4
4.5
V
Output Source Current
Io
+
0.5V < V
3
< 3.5V
2
-
-
mA
Output Sink Current
Io
-
0.5V< V
3
< 3.5V
-0.2
-0.6
-
mA
Output Section
Characteristic Symbol
Test
Condition Min.
Typ.
Max.
Unit
Common-Emitter V
E
= 15V, I
C
= 200mA
-
1.1
1.3
Output Satur-
ation Voltage Emitter-Follower
V
CE(SAT)
V
C
=15V, I
E
= 200mA
-
1.5
2.5
V
Collector off-state Current
I
C(off)
V
CC
= V
C
= 40V, V
E
= 0
-
2
100
Emitter off-state Current
I
E(off)
V
CC
= V
C
= 40V, V
E
= 0
-
-
-100
Output Control(Pin 13)
Output Control Voltage
Required for single-Ended or
Parallel Output Operation
V
OCL
-
- - 0.4
V
Output Control Voltage Req-
uired for Push-pull operation
V
OCH
-
2.4 -
-
V
Total Device
Standby power Supply
Current
I
CC
-
- 6 10
mA
: These limits apply when the voltage measured at Pin 3 is with in the range specified.
KSI-L010-000
4
S494P
Output AC Characteristic
Characteristic Symbol
Test
Condition Min.
Typ.
Max.
Unit
Common Emitter
-
100
200
Rise Time
Emitter Follower
t
r
-
- 100 200
Common Emitter
-
25
100
Fall Time
Emitter Follower
t
f
-
- 40 100
ns
Block Diagram
12
14
7
6
5
4
1
2
16
15
13
3
R e fe r e n c e
R e gu l a t or
O s c
+
-
+
-
+
-
+
-
T F.F
8
9
11
10
V c c
R e f O u t
G ND
R
T
C
T
De a d-T i me
Con t r ol
Non -i n v
In pu t
In v -In pu t
Non -i n v
In pu t
In v -In pu t
Fe e d-Ba c k
De a d T i me
CO MP A R A T O R
P W M
CO MP A R A T O R
EA 1
EA 2
O u t pu t Con t r ol
C
1
E
1
C
2
E
2
KSI-L010-000
5
S494P
INFORMATION
The basic oscillator(switching)frequency is controlled by an external resistor (Rt) and
capacitor(Ct). The relationship between the values of Rt Ct and frequency is shown in.
The level of the sawtooth wave form is compared with an error voltage by the pulse width
modulated comparator. The output of the PWM Comparator directs the pulse steering flip
flop and the output control logic.
The error voltage is generated by the error amplifier. The error amplifier boosts the voltage
difference between the output and the 5V internal reference. See Figure 7 for error amp
sensing techniques. The second error amp is typically used to implement current limiting.
The output control logic (Pin13) selects either push-pull or single-ended operation of the
output transistors (see Figure6). The dead time control prevents on-state overlap of the
output transistors as can be seen is Figure5. The dead time is approximately 3 to 5% of the
total period if the dead time control(pin4) is grounded. This dead time can be increased by
connecting the dead time control to a voltage up to 5 V. The frequency response of the
error amps can be modified by using external resistors and capacitors. These components
are typically connected between the compensation terminal (pin3) and the inverting input
of the error amps(pin2 or pin15). The switching frequency of two or more S494 circuits can
be synchronized. The timing capacitor, Ct is connected as shown in Figure 8. Charging
current is provided by the master circuit. Discharging is through all the circuits slaved to
the master. Rt is required only for the master circuit.
Operating Waveform
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