IS32LT3958-ZLA3-TR

The IS32LT3958 is a current mode PWM controller designed to drive a low side external NMOS FET for wide input/output voltage range and high LED current applications. An external resistor senses the high side output current of the LED string. A high side sense resistor is the most flexible current sensing scheme, since it functions in either boost or buck-boost mode configurations. The controller can be configured with an external resistor to operate between 100kHz~1MHz frequency resulting in small external inductor and capacitors while maintaining high efficiency. A single capacitor is all that is required to set the spread spectrum dither frequency to reduce the radiated peak emission and optimize the system EMI performance. The IS32LT3958 integrates circuitry to detect output open/short, RT/SYNC pin short, VDD short, VCC undervoltage lockout and over temperature fault conditions. These failure conditions can be reported by the open drain fault reporting FAULTB pin. The current monitor pin (IMON) output can be used for continuous LED status check. The IS32LT3958 can modulate LED current using either analog and/or PWM dimming techniques. The IS32LT3958 features two independent analog dimming pins, ICTRL and ADJR. Input DC voltage in the range of 0.06V~2V on the ICTRL pin and/or ADJR pin is required for analog dimming. PWM dimming is achieved by directly modulating the PWM/EN pin with desired PWM duty cycle or by enabling the internal PWM generator circuit. With the internal PWM generator circuit, IS32LT3958 can achieve standalone dual brightness level output. The duty cycle and frequency of the internal PWM generator is easily programmed by external resistors. The IS32LT3958 is available in an eTSSOP-20 package with an exposed pad for enhanced thermal dissipation. It operates from 5V to 70V over the temperature range of -40°C to +150°C.

Applications

• Automotive
• Headlight
• Daytime running light
• Fog light
• Tail light

Key features

• Wide high voltage input range: 5V to 70V
• Supports boost, buck-boost, SEPIC and buck topology
• Supports either analog, internal PWM dimming or external PWM dimming
• Standalone dual brightness output by internal PWM dimming - Integrated PWM generator - 100Hz~1kHz adjustable PWM frequency - 5%~100% adjustable PWM duty cycle
• Excellent analog dimming capability - Two analog dimming pins - LED binning capability - LED over temperature current roll-off
• Externally programmable input undervoltage lockout
• ±2.8% output current accuracy over -40°C ~ +150°C temperature
• Adjustable operating frequency range of 100kHz~1MHz
• Programmable soft start to avoid inrush current
• EMI reduction capabilities - Programmable spread spectrum function - Operating frequency synchronization with external clock source
• Fault protection with reporting: - VCC undervoltage lockout (not reported) - Programmable output overvoltage protection - Output short circuit protection - RT/SYNC pin short protection - VDD pin short protection - VDD undervoltage lockout (not reported) - Over temperature protection
• AEC-Q100 Qualified
• RoHS & Halogen-Free compliant (Pb-free) package