UTC494 LINEAR INTEGRATED CIRCUIT

VOLTAGE MODE PWM CONTROL

CIRCUITS

DESCRIPTION
The UTC494 incorporate on a single monolithic chip all the
functions required in the construction of a pulse-width
modulation control circuit.Designed primarily for power supply
control, the device offers the systems engineer the flexibility to
t ai l or t h e p ow er s u p p l y c on t r ol c i r c u it ry t o it s DIP-16
application.
The UTC494 contains an error amplifier,current-limiting
amplifier, an on-chip adjustable oscillator, a dead time control
c o m p a r a t o r , p u l s e - s t e e r i n g c o n t r o l f l i p - f l op , a 5 -
volt ,1% precision supply regulator,and output control
circuits.
The error amplifier exhibits a common-mode Voltage range
from -0.3V to V CC -2V.The current-limit amplifier exhibits a
common-mode Voltage range from -0.3V to 3V with an offset
Voltage of approximately 80 mV in series with the inverting SOP-16
input to ease circuit design requirements. The dead-time
c ont rol c om parat or has a fixed offset t hat provides
approximately 5% dead time when externally altered. The on-
chip oscillator may be bypassed by terminating RT(pin 6) to the
reference output and providing a sawtooth Input to CT(pin 5),or FEATURES
i t m ay b e u s ed t o d r i v e t h e c om m on c i r c u i t s i n *Complete PWM Power Control Circuitry
synchronous multiple-rail power supplies. *Uncommitted Outputs for 200 mA Sink or
The Uncommitted output transistors provide either common- Source Current
em itter or em itter-follower output capability.Each device *Output Control Selects single-Ended or Push-
provides for push-pull or single-ended output operation,which Pull Operation
m ay be selected through the output-control function. the *Internal Circuitry Prohibits Double control Over
architecture of these devices prohibits the possibility of either Total Range
being pulsed twice during push-pull *Circuit architecture Allows easy Synchron -
operation. Ization
*Undervoltage Lockout

ABSOLUTE MAXIMUM RATINGS

(Unless otherwise noted ,all is over operating free-air temperature Range)
Characteristic Symbol Value Unit
Supply Voltage(note 1) Vcc 40 V
Amplifier Input Voltage Vi Vcc+0.3 V
Collector Output Voltage Vo 41 V
Collector Output Current Ico 250 mA
Continuous total dissipation at(or for below) 25 PD 1000 mW
free air temperature(note 2)
Operating Temperature Range Topr 0 to 70 °C
Storage Temperature Range Tstg -65 to 150 °C
lead Temperature 1.6mm from case for 60 Tcase 300 °C
sec.

note1: All voltage values,except differential voltages are with respect to the network ground terminal.
note 2:For operation above 25°C free-air temperature,The dissipation derates with 9.2mW/°C.

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UTC494 LINEAR INTEGRATED CIRCUIT

BLOCK DIAGRAM

RECOMMENDED OPERATING CONDITIONS

Characteristic Symbol Values
min max Unit
Supply Voltage Vcc 7 36 V
Amplifier Input Voltage Vi -0.3 Vcc-2 V
Collector Output Voltage Vo 40 V
Collector Output Current(each Transistor) Ic 200 mA
Current into feedback If 0.3 mA
Timing capacitor CT 0.47 10000 nF
Timing Resistor RT 1.8 500 kΩ
Oscillator frequency fosc 1 300 kHz
Operating free-air temperature Ta 0 70 °C

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UTC494 LINEAR INTEGRATED CIRCUIT
ELECTRICAL CHARACTERISTICS
(Over recommended operating free-air temperature range,V CC=15V,f=1kHz,Unless otherwise specified)
Characteristic Test Conditions Min Typ Max Unit
Reference Section
Output voltage Io=1mA 4.9 5 5.1 V
Input regulation Vcc=7V to 36V 2 25 mV
Output Regulation Io=1 to 10mA 1 15 mV
Output Voltage change with ∆TA=MIN to MAX(note 2) 0.2 1 %
Temperature
Short-circuit output Current Vref=0 35 mA
Characteristic Test Conditions Min Typ Max Unit
Oscillator section
Frequency CT=0.01µF,RT=120kΩ 10 kHz
Standard Deviation of Frequency All Values of Vcc CT,RT,TA 10 %
constant
Frequency Change with Voltage Vcc=7V to 36V,Ta=25°C 0.1 %
Frequency Change with CT=0.01µF,RT=12kΩ,∆TA=MIN 12 %
temperature to MAX
Amplifier Section
Input offset Voltage Error Vo(pin 3)=2.5V 2 10 mV
Input offset Current Vo(pin 3)=2.5V 25 250 nA
Input bias Current Vo(pin 3)=2.5V 0.2 1 µA
Common-mode Input Voltage Error Vcc=7V to 36 V -0.3 Vcc-2 V
Range
Open-Loop Voltage Amplification ∆Vo=3V, Vo=0.5V to 3.5V 70 95 dB
Unity-Gain Bandwidth 800 kHz
Common-Mode Rejection ratio Error Vcc=36V,TA=25°C 65 80 dB
output sink current(pin 3) VID=-15mV to -5V 0.3 0.7 mA
V(pin 3)=0.5V
Output source Current(pin 3) VID=15mV to 5V V(pin 3)=3.5V -2 mA
Output Section
Collector off-state current VCE=40V,Vcc=36V 2 100 µA
Emitter off-state Current VCC=VC=36V,VE=0 -100 µA
Collector -emitter Saturation Common- VE=0,Ic=200mA 1.1 1.3 V
Voltage emitter
Emitter- Vc=15V,IE=-200mA 1.5 2.5
Follower
Output Control input Current Vi=Vref 3.5 mA
Dead Time Control Section
Input bias (pin 4) Vi=0 to 5.25V -2 -10 µA
Maximum duty cycle,each output VI(pin 4)=0 45 %
Input threshold Voltage(pin 4) Zero duty Cycle 3 3.3 V
Maximum duty cycle 0
PWM comparator Section
Input Threshold Voltage(pin 3) Zero Duty cycle 4 4.5 V
Input sink current (pin 3) Vpin 3= 0.7V 0.3 0.7 mA
Total Device
Standby supply current Vcc=15V pin 6 at Vref,all other Inputs and 6 10 mA
outputs open

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UTC494 LINEAR INTEGRATED CIRCUIT
Vcc=40V 9 15
Average supply current Vpin 4=2V 7.5 mA
Switching Characteristics,Ta=25°C
Output Voltage rise time Common-emitter configuration 100 200 ns
Output Voltage fall time 25 100 ns
Output Voltage rise time Emitter-follower configuration 100 200 ns
Output Voltage fall time 40 100 ns
note 1:All typical Values except for temperature coefficient are at Ta=25°C.
note 2:For conditions shown as MIN or MAX, use appropriate value under recommended operating conditions.
note 3:Duration of the short-circuit should not exceed one second.
note 4:Standard deviation is a measure of the statistical distribution the mean as derived from the formula :
N
2
(xn-x)
= n=1
N-1

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UTC494 LINEAR INTEGRATED CIRCUIT

PIN CONFIGURATIONS

NONINV NONINV
1 16
INPUT INPUT

INV INPUT 2 15 INV INPUT

FEEDBACK 3 14 Vref

DEAD-TIME OUTPUT
4 13
CONTROL CONTROL

CT 5 12 Vcc

RT 6 11 C2

GND 7 10 E2

C1 8 9 E1

TYPICAL APPLICATION CIRCUIT

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UTC494 LINEAR INTEGRATED CIRCUIT
TEST CIRCUIT

Vcc=15V

2W 2W
12 150 150
TEST
INPUTS 4 Vcc 8
DEAD-TIME C1
3 9 OUTPUT 1
FEEDBACK E1
12k
6
RT
5 11
CT C2
0.01 F 1
OUTPUT 2
E2 10
2
ERROR
16 AMPLIFIER
15
Vref
13 OUTPUT OUTPUT 14
CONTROL
50k
7

VOLTAGE
at C1

VOLTAGE
at C2

VOLTAGE
at CT

DEAD-TIME THRESHOLD VOLTAGE

CONTROL INPUT

THRESHOLD VOLTAGE
FEEDBACK

FIG 1. OPERATIONAL TEST CIRCUIT AND WAVEFORMS

ERROR
AMPLIFIER
1

Vin
FEEDBACK
2 TERMINAL

16

Vref
15
ERROR
AMPLIFIER
FIG 2. AMPLIFIER CHARACTERISTICS

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UTC494 LINEAR INTEGRATED CIRCUIT

Vcc Vcc
EACH
90% 90% OUTPUT 90% 90%
EACH CIRCUIT Q
68
OUTPUT Q
Vc Ve
CIRCUIT
15pF 10% 10% 10% 10%
68 15pF tr tf
tr tf

FIG. 3 COMMON-EMITTER CONFIGURATION FIG. 4 EMITTER -FOLLOWER CONFIGURATION

TYPICAL PERFORMANCE CHARACTERISTICS

100
5
10
Vcc=15V
Vcc=15V
T V
Voltage Amplification (dB) 80 T
Oscillator Frequency (Hz)

4
10 CT=0.001 F

60
CT=0.01 F
3
10
40
CT=0.1 F
2
10
CT=1 F 20

1 0
10
3 4 5 6 2 3 4 5 6
10 10 10 10 10 10 10 10 10
RT(Timing Resistance) ( ) Frequency (Hz)

FIG 5. Oscillator Frequency and Frequency Variation Fig.6 Amplifier Voltage Amplification
Vs
Timing Resistance

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UTC494 LINEAR INTEGRATED CIRCUIT
PACKAGE DIMENSIONS
DIP-16-300-2.54 Unit: mm

SOP-16-225-1.27 Unit: mm

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