ky SGS-THOMSON MICROELECTRONICS S$G2525A/2527A $G3525A/3527A | REGULATING PULSE WIDTH MODULATORS For complete specification refer to Linear & Switching Voltage Regulators Appl. Manual ". { Order Code AMLISVOREST/1 ) * 8TO 35 V OPERATION = 5.1 V REFERENCE TRIMMED TO: 1% : a 100 Hz TO 500 KHz OSCILLATOR RANGE a SEPARATE OSCILLATOR SYNC TERMINAL / a ADJUSTABLE DEADTIME CONTROL INTERNAL SOFT-START PULSE-BY-PULSE SHUTDOWN INPUT UNDERVOLTAGE LOCKOUT WITH : HYSTERESIS , a LATCHING PWM TO PREVENT MULTIPLE PULSES a DUAL SOURCE/SINK OUTPUT DRIVERS / DESCRIPTION The $G3525A/3527A series of pulse width modula- tor integrated circuits are designed to offer improved performance 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 allows multiple units to be slaved or a single unit to be synchronized to an external system clock. A . single resistor between the Cr and the discharge terminals provide a wide range of dead time ad- i 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 circuity and the output stages, providing instan- : taneous turn off through the PWM latch with pulsed shutdown, as well as soft-start recycle with longer shuidown commands. These functions are also controlled by an undervoitage lockout which keeps the outputs off and the soft-start capacitor dis- charged for sub-normal input voltages. This lockout circuitry includes approximately 500 mV of hys- teresis for jitter-free operation. Another feature of these PWM circuits is a latch following the compara- tor. Once a PWM pulses has been terminated for any reason, the outputs will remain off for the dura- tion of the period. The latch is reset with each clock pulse. The output stages are totem-pole designs ca- pable of sourcing or sinking in excess of 200 mA. The SG3525A output stage features NOR logic, giv- ing a LOW output for an OFF state. The SG3527A utilizes OR logic which results in a HIGH output level! when OFF. PIN CONNECTIONS AND ORDERING NUMBERS (top view) VS iw.input ff 16f} VREE T 2 5 Vv numeut Type Plastic DIP $016 SYNC 14[} ourpuT 8 $G2525A $G2525AN $G2525AP . 3 v osc.ourrur ff ) SG2527A SG2527AN SG2527AP i 5 2 OUND oT f rou SG3525A SG3525AN SG3525AP | Ry fis vf) OUTPUT A i SG3527A SG3527AN SG3527AP : DISCHARGE {/7 tof] SHUTDOWN i SOFT - start | 8 of) come S- 6414 1/9 October 1992 559