SG1525AJ

Overview

The SG1525AJ is a regulating pulse width modulator integrated circuit designed for switching power supply applications. It operates within an 8V to 35V voltage range and features a +5.1V reference trimmed to ±1% initial accuracy. The oscillator frequency ranges from 100Hz to 500kHz, with a separate sync terminal for external clock synchronization. Output drivers are capable of sourcing or sinking over 200mA using a totem-pole design. The device includes built-in soft-start, undervoltage lockout, and latch protection to prevent multiple pulses.

Feature Summary

• Integrated error amplifier with common-mode input range including the reference voltage, eliminating the need for external potentiometers and divider resistors.
• Built-in soft-start circuitry controlled by a single external timing capacitor and a dedicated Shutdown pin for instantaneous turn-off.
• Output stage latch prevents multiple pulses by keeping outputs off for the duration of the period after any PWM termination.
• Compliance with MIL-STD-883B standards and availability in radiation-hardened processing options.

Applications

• Switching power supplies requiring improved performance and reduced external component count
• Systems requiring synchronization of multiple PWM units or slaving to an external system clock
• Applications necessitating precise reference voltage without external trimming components

Procurement Notes

Verify the specific ordering suffix and package variant (e.g., CDIP) against the manufacturer's current datasheet to ensure compatibility with the required military or commercial specifications. Confirm that the requested part number matches the exact logic output configuration (NOR vs OR) intended for the design, as variations exist within the series. Check for radiation hardness requirements if applicable to the target environment.

Selection Notes

Select this component when a voltage-mode PWM controller with high-output drive capability and integrated protection features is required. The inclusion of a latch and undervoltage lockout simplifies design complexity compared to basic PWM ICs. Ensure the application can accommodate the 100Hz to 500kHz oscillator range and utilizes the appropriate output logic type for the load interface.

Part Context

The SG1525AJ belongs to the SG1525A/SG1527A series of regulating pulse width modulators. This family is characterized by its ability to reduce external parts count through integrated references and amplifiers. The SG1525A specifically utilizes NOR logic for its output stage, resulting in a low output state when turned off, distinguishing it from the SG1527A which uses OR logic.

Replacement Considerations

Public confirmed substitute part numbers include SG1525AJ-JAN and SG1525AL/883B. Verify functional equivalence regarding output logic and package dimensions before substitution.