LT1186F Datasheet | Linear Technology

LT1186F DAC Programmable CCFL Switching Regulator (Bits-to-Nits TM) Features s s s s s s APPLICATIONS s s s face modes including standard SPI mode and pulse mode. On power-up, the DAC counter resets to half-scale and the Wide Battery Input Range: 4.5V to 30V DAC configures to SPI or pulse mode depending on the CS Grounded Lamp or Floating Lamp Configurations signal level. In SPI mode, the system microprocessor Open Lamp Protection serially transfers the present 8-bit data and reads back the Precision 50µA Full-Scale DAC Programming Current previous 8-bit data. In pulse mode, the upper six bits of the Standard SPI Mode or Pulse Mode DAC configure as increment-only (1-wire interface) or DAC Setting Is Retained in Shutdown increment/decrement (2-wire interface) operation depend U ing on the DIN signal level. The LT1186F control circuitry operates from a logic supply voltage of 3.3V or 5V. The IC also has a battery supply voltage pin that operates from 4.5V to 30V. The LT1186F draws 6m A typical quiescent current. An active low shutdown pin reduces total supply current to 35µA for standby operation and the DAC retains its last setting. A 200k Hz switching frequency minimizes magnetic ponent size. Current mode switching techniques with cycle-by-cycle limiting gives high reliability and simple loop frequency pensation. The LT1186F is available in a 16-pin narrow SO package. , LTC and LT are registered trademarks of Linear Technology Corporation. Bits-to-Nits is a trademark of Linear Technology Corporation. 1 Nit = 1 Candela/meter2 Notebook and Palmtop puters Portable Instruments Retail Terminals DESCRIPTION The LT ®1186F is a fixed frequency, current mode, switching regulator that provides the control function for Cold Cathode Fluorescent Lighting (CCFL). The IC includes an efficient high current switch, an oscillator, output drive logic, control circuitry and a micropower 8-bit 50µA fullscale current output DAC. The DAC provides simple “bitsto-lamp current...