IS32BL3556-ZLA3

IS32BL3556-ZLA3 特徵

概觀

The IS32BL3556 is a step-up controller with an integrated switching FET for driving white LED arrays in LCD panel backlight applications. The boost controller is a current mode, fixed frequency architecture with the switching frequency set by an external resistor. The integrated boost controller generates the minimum output voltage to keep all LEDs illuminated at the set current. The current in each of the 4 channels is programmed to a specific value with an external current set resistor and matched to within 1%. LED dimming is achieved using an external digital PWM signal to either adjust the internal ISET current or pulse-width-modulate the LED intensity. The LED sinks have a fast response to a PWM input making it possible to achieve a high contrast ratio of 10,000:1. A synchronization pin can be used to synchronize multiple IS32BL3556 devices or to synchronize with the external PWM source in the range of 580 kHz to 2.3MHz. The high switching frequency allows the IS32BL3556 to operate above the AM radio band. The IS32BL3556 integrates a control block to drive an external P-Channel FET to disconnect the input supply from the system whenever a fault is detected. It has safety protection features to prevent damage during fault conditions. Protection features include output short and overvoltage, open or shorted diode, open or shorted LED pin, shorted boost switch, shorted FSET or ISET resistor, and IC over temperature. A dual level cycle-by-cycle current limit function provides soft start and protects the internal current switch against high current overloads. The IS32BL3556 is available in a thermally enhanced eTSSOP-20 package.