The LTC1697 is a synchronous buck switching regulator designed to control a single 1W cold cathode fluorescent lamp (CCFL). It features high efficiency, low power, wide input voltage range, and high accuracy dimming.
The LTC1697 is a synchronous current‑mode regulator designed to drive a single 1 W cold‑cathode fluorescent lamp (CCFL). It operates from a 2.8 V to 5.5 V input, provides very low shutdown current (<2 µA), and includes an internal PWM dimming system whose frequency is set by an external capacitor.
Typical applications include handheld computers, portable instruments, and other battery‑powered devices that require efficient back‑lighting. The device features over‑voltage protection, thermal shutdown, and a programmable lamp‑current resistor for precise brightness control.
| Input Voltage Range | 2.8 V – 5.5 V |
|---|---|
| Shutdown Current | < 2 µA |
| Switching Frequency | 240 kHz – 370 kHz |
| Switch On Resistance (Ron) | 0.18 Ω (at Vin = 4 V) |
| Maximum Switch Current | 0.9 A – 1.6 A |
| Undervoltage Lockout | 2.47 V |
| Shutdown Input Low Voltage | < 0.4 V |
The device operates from 2.8 V to 5.5 V supply voltage.
The frequency is determined by the external capacitor on the Cp (Pin 1) according to the equation 5 Hz / C (µF).
The switch current limit is specified between 0.9 A and 1.6 A.
Pull the SHDN pin low (below ~0.1 V) or pull the Vpim pin low for more than about 50 ms to shut the device down.