SG2525A

SG3525A

REGULATING PULSE WIDTH MODULATORS

.

8 TO 35 V OPERATION

.

5.1 V REFERENCE TRIMMED TO

± 1 %

.

100 Hz TO 500 KHz OSCILLATOR RANGE

.

SEPARATE OSCILLATOR SYNC TERMINAL

.

ADJUSTABLE DEADTIME CONTROL

.

INTERNAL SOFT-START

.

PULSE-BY-PULSE SHUTDOWN

.

INPUT UNDERVOLTAGE LOCKOUT WITH

HYSTERESIS

.

LATCHING PWM TO PREVENT MULTIPLE

PULSES

.

DUAL SOURCE/SINK OUTPUT DRIVERS

DESCRIPTION

The SG3525A series of pulse width modulator inte-

grated circuits are designed to offer improved per-

formance and lowered external parts count when

used in designing all types of switching power sup-

plies. The on-chip + 5.1 V reference is trimmed to

±

1 % and the input common-mode range of the error

amplifier includes the reference voltage eliminating

external resistors. A sync input to the oscillator al-

lows multiple units to be slaved or a single unit to be

synchronized to an external system clock. A single

provide a wide range of dead time ad-

justment.

These devices also feature built-in soft-start circuitry

with only an external timing capacitor required. A

shutdown terminal controls both the soft-start circu-

ity and the output stages, providing instantaneous

turn off through the PWM latch with pulsed shut-

down, as well as soft-start recycle with longer shut-

down commands. These functions are also control-

led by an undervoltage lockout which keeps the out-

puts off and the soft-start capacitor discharged for

sub-normal input voltages. This lockout circuitry in-

cludes approximately 500 mV of hysteresis for jitter-

free operation. Another feature of these PWM cir-

cuits is a latch following the comparator. Once a

PWM pulses has been terminated for any reason,

the outputs will remain off for the duration of the pe-

riod. The latch is reset with each clock pulse. The

output stages are totem-pole designs capable of

sourcing or sinking in excess of 200 mA. The

SG3525A output stage features NOR logic, giving a

LOW output for an OFF state.

DIP16

16(Narrow)

Type

Plastic DIP

SO16

SG2525A

SG2525AN

SG2525AP

SG3525A

SG3525AN

SG3525AP

PIN CONNECTIONS AND ORDERING NUMBERS (top view)

®

June 2000

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