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S494P
SSeemmiiccoonndduuccttoorr
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 -40℃to85℃.
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
Pulse Width Modulation
Type NO. Marking Package Code
S494P S494P DIP-16
Outline Dimensions unit : mm
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
1
S494P
Absolute Maximum Ratings Ta =2 5°C
Characteristic Symbol Ratings Unit
supply voltage VCC 42 V
Voltage From Any Pin to Ground
(except pin 8 and pin 11)
Output Collector Voltage VC1, VC2 42 V
Peak Collector Current IC1, IC2 250 mA
Power Dissipation PD 1500 mW
Operating Temperature T
Storage Temperature T
Recommended Operating Condition
Characteristic Symbol Min. Max. Unit
supply voltage VCC 7 40 V
Voltage on Any Pin Except Pin
8 and 11(Referenced to Ground)
Output Voltage VC1, VC2 -0.3 40 V
Output Collector Current IC1, IC2 - 200 mA
Timing Capacitor Ct 470 - PF
Timing Capacitor Ct - 10
Timing Resistor Rt 1.8 500
Oscillator Frequency f
V
V
IN
-40 ~ 85
opr
-65 ~ 150
stg
-0.3 VCC+0.3 V
V
IN
1 300 KHz
OSC
+0.3 V
CC
°C
°C
㎌
㏀
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
Load Regulation V
Temperature Coefficient -
7V < Vcc < 40V - 2 25 mV
LINE
LOAD
1mA< I
0°C < Ta <70°C
<10mA
REF
- 1 15 mV
- 0.01 0.03
%/°C
Oscillator Section
Characteristic Symbol Test Condition Min. Typ. Max. Unit
C
Oscillator Frequency f
Oscillator Frequency Change
Over Operating Temperature
Range
Δ f
OSC
SOC
C
=0.01 ㎌, R
t
=0.01 ㎌, R
t
=12 ㏀
t
=12 ㏀
t
- 10 -
- - 2 %
㎑
KSI-L010-000
2
S494P
Dead Time Control Section
Characteristic Symbol Test Condition Min. Typ. Max. Unit
Input Bias Current (Pin4) I
Max. Duty cycle, Each Output DC
Input Threshold
Voltage
Zero Duty - 3 3.3
Max Duty
Error Amplifier Section
Characteristic Symbol Test Condition Min. Typ. Max. Unit
Input Offset Voltage V
Input Offset Current I
Input Bias Current IIB V3 = 2.5V - 0.2 1
Input Common Mode
voltage Range
Large Signal Open Loop
Voltage Range
Unity Gain Band width fC - - 650 -
Vcc = 15V, 0V < V4 < 5.25V - -2 -10
IB(DT)
Vcc = 15V, Pin4 = 0V,
V
V
G
(Max)
TH
IOS
IOS
ICR
VO
Output Control Pin = Vref
-
V3 = 2.5V - 2 10 mV
V3 = 2.5V - 25 250
7V ≤ V
0.5V ≤ V
CC
≤ 40V
≤ 3.5V
3
43 - 45
0 - -
-0.3 - V
60 74 - dB
CC
V
㎂
%
V
nA
㎂
㎑
PWM Comparator Section (Pin3)
Characteristic Symbol Test Condition Min. Typ. Max. Unit
Inhibit Threshold Voltage V
Output Source Current Io+ 0.5V < V3 < 3.5V 2 - -
Output Sink Current Io
Zero duty cycle - 4 4.5 V
THI
-
0.5V< V3 < 3.5V -0.2 -0.6 -
Output Section
Characteristic Symbol Test Condition Min. Typ. Max. Unit
Output Satur ation Voltage
Collector off-state Current I
Emitter off-state Current I
Output Control(Pin 13)
Output Control Voltage
Required for single-Ended or
Parallel Output Operation
Output Control Voltage Required for Push-pull operation
Total Device
Standby power Supply
Current
: These limits apply when the voltage measured at Pin 3 is with in the range specified.
Common-Emitter VE= 15V, IC = 200mA - 1.1 1.3
Emitter-Follower
V
CE(SAT)
C(off)
E(off)
V
OCL
V
OCH
I
CC
V
=15V, IE = 200mA - 1.5 2.5
C
VCC = VC = 40V, VE = 0 - 2 100
VCC = VC = 40V, VE = 0 - - -100
- - - 0.4
- 2.4 - -
- - 6 10
mA
mA
V
㎂
V
V
mA
KSI-L010-000
3
p
p
p
p
Output AC Characteristic
Characteristic Symbol Test Condition Min. Typ. Max. Unit
Rise Time
Fall Time
Common Emitter - 100 200
Emitter Follower
Common Emitter - 25 100
Emitter Follower
Block Diagram
tr -
tf -
S494P
- 100 200
- 40 100
ns
Dead-Time
Non -in v
Inv-In
Inv-In
Feed-Back
Vcc
Ref Out
GND
R
C
Control
In
ut
Non -in v
In
ut
T
ut
ut
13
12
14
7
6
5
T
4
1
2
16
15
3
Reference
Regulator
Osc
Dead Time
COMPARATOR
+
-
EA1
+
-
EA2
+
-
T F.F
+
-
PWM
COMPARATOR
Output Control
11
10
C
8
1
9
E
1
C
2
E
2
KSI-L010-000
4
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
KSI-L010-000
5
S494P
K
FOUT
436
5
615
410119
7
D
K12K
0
0
Tes t Circui t
Fig.1Error Amplifier Test Circuit Fig.2 Current Limit sense Amplifier Test Circuit
+
V
IN
-
REF
V
16
15
1
2
+
ERROR
AMP
-
+
ERROR
AMP
-
3
V
REF
V
+
V
IN
-
16
15
1
2
+
ERROR
AMP
-
+
ERROR
AMP
-
3
V
Fig. 3 Common-Emitter Configuration Fig. 5 Dead-Time and Feedback Control
Test circuit and Waveform
Test Circuit
Eac h ou tpu t
Transistor
90%
10%
Tr
15V DC
C
E
68
15pF
T
f
Vc
90%
10%
TEST
Inputs
0.01uF
1
13 1
50
DEAD
TIME
FEED BAC
T
R
T
C
1
(+)
2
(-)
(+)
(-)
OUTPUT
CONTR OL
Vcc=15V
12
Vcc
GN
RE
15
2W
C1
E1
C2
E2
15
2W
8
OUTPUT1
OUTPUT2
Fig. 4 Emitter-Follower Configuration Test circuit and waveform Voltage waveform
68
15V DC
C
15pF
90%
10%
E
V
GND
Tr
10%
T
f
Each output
Transistor
KSI-L010-000
90%
6
S494P
L
APPLICATION CIRCUIT
Fig. 6 Output Connections for Single-Ended Fig. 7 Error Amplifier Sensing Techniques
and Push-Pull Configurations
OUTPUT
CONTROL
0 < V
9
11
10
C1
E1
C2
E2
OC
Q1Q28
< 4V
S ING L E-E NDED CO NF I GURA TI ON
C
Q
1 TO 500 mA(MAX)
E
Q
Vo
R1
REF
V
R2
TO OUTPUT
VOLTAGE OF
SYSTEM
1(16) +
2(15) -
ERROR
AMP
POSITIV E OUTPUT
VOLTAGE
3
REF
R1
V
R2
Vo
TO OUTPUT
VOLTAGE OF
SYSTEM
2.4V <V OC<V
Q1
REF
OUTPUT
Q2
CONTRO
PUSH-PULL CONFI GURATI ON
8
9
11
10
C1
250 mA(MAX )
E1
C2
E2
250 mA(MAX )
1(16)
+
3
2(15)
-
NEGA T I V E OUT PUT
VOLTAGE
Vo = -V
REF
R1
R2
Fig. 8 Slaving Tow or More Control Circuits Fig. 9Error Amplifier and Current Limit
Sense Amplifier Output Circuits
REF
V
14
6
T
R
MASTER
5
T
C
REF
T
T
R
C
6
5
14
V
T
R
SLAV E
(A DDI TIONAL
T
C
CIRCUI T S )
TO REMAI NDER
Vcc
REF
V
OF ERROR
AMPLIFIER
CIRCUI T
0.6mA
TO REMAI NDER
OF ERROR
AMPLIFIER
CIRCUI T
TO COMPENSATION
PWM COMP ARA T OR
INPUT
KSI-L010-000
7
Electrical Characteristic Curves
Fig. 1 V
Fig. 3 t
CE(sat) -IC
OSC
- R
T
Fig. 2 VCE -IE
Fig. 4 A
VOL
, Phase - f
S494P
Fig. 5 I
CC
- VCC
∆
Ω
φ
KSI-L010-000
8
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