Document
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 tailor the power supply control circuitry to its application.
The UTC494 contains an error amplifier,current-limiting amplifier, an on-chip adjustable oscillator, a dead time control com parator,pulse-steering control flip-flop,a 5volt ,1% precision supply regulator,and output control circuits.
The error amplifier exhibits a common-mode Voltage range from -0.3V to VCC-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 input to ease circuit design requirements. The dead-time control comparator has a fixed offset that provides approximately 5% dead time when externally altered. The onchip oscillator may be bypassed by terminating RT(pin 6) to the reference output and providing a sawtooth Input to CT(pin 5),or it m ay be used to drive the common circuits in synchronous multiple-rail power supplies.
The Uncommitted output transistors provide either commonem itter or em itter-follower output capability.Each device provides for push-pull or single-ended output operation,which m ay be selected through the output-control function. the architecture of these devices prohibits the possibility of either being pulsed twice during push-pull
operation.
DIP-16
SOP-16
FEATURES
*Complete PWM Power Control Circuitry *Uncommitted Outputs for 200 mA Sink or
Source Current *Output Control Selects single-Ended or Push-
Pull Operation *Internal Circuitry Prohibits Double control Over
Total Range *Circuit architecture Allows easy Synchron -
Ization *Undervoltage Lockout
ABSOLUTE MAXIMUM RATINGS
(Unless otherwise noted ,all is over operating free-air temperature Range)
Characteristic
Symbol
Supply Voltage(note 1)
Vcc
Amplifier Input Voltage
Vi
Collector Output Voltage
Vo
Collector Output Current
Ico
Continuous total dissipation at(or for below) 25 free air temperature(note 2)
PD
Operating Temperature Range
Topr
Storage Temperature Range
Tstg
lead Temperature 1.6mm from case for 60 sec.
Tcase
Value 40
Vcc+0.3 41 250
1000
0 to 70 -65 to 150
300
Unit V V V mA
mW
°C °C °C
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.
YOUWANG ELECTRONICS CO.LTD
1
2010.09.26 V1.4
UTC494
BLOCK DIAGRAM
LINEAR INTEGRATED CIRCUIT
RECOMMENDED OPERATING CONDITIONS
Characteristic
Symbol
Supply Voltage Amplifier Input Voltage Collector Output Voltage Collector Output Current(each Transistor) Current into feedback Timing capacitor Timing Resistor Oscillator frequency Operating free-air temperature.