ISSI IS31LT3948

Description

The IS31LT3948 is a PFM step-up DC-DC converter designed for driving the white LED arrays for large size LCD panel backlighting applications. It candeliver stable constant output current from a few milliamps up to 2A, programmed via an external resistor.

The IS31LT3948 utilizes a control scheme in which the output is automatically adjusted to the optimum output voltage for the system, maximizing theefficiency. Furthermore, the control scheme is inherently stable removing the need to provide additional loop compensation.

The device features external PWM dimming, which allows the flexible control of the back-lighting luminance.

The IS31LT3948 has a wide input voltage range from 5V to 100V (Note). An integrated OVP circuit protects the chip and the system even under no-loadconditions.

The chip is assembled in SOP-8 package. It operates from 5V to 100V over two temperature ranges of -40°C to +85°C and -40°C to +125°C.

Note: The IS31LT3948 has an internal 5V shunt regulator connected to the VCC pin. A dropping resistor must be connected between the VCC pinand VIN to limit current flow. VIN voltages above 100V are allowed but care must be taken to ensure that the output voltage remains greater than VIN,and that the NMOS voltage rating is sufficiently large.

Features

• Wide input voltage range: 5V~100V
• Constant current output limited only by external component selection (Note)
• No loop compensation required
• Internal over-voltage protection
• Internal over-temperature protection
• Operating temperature range -40C to +85C (IS31LT3948-GRLS2-TR)
• Operating temperature range -40C to +125C (IS31LT3948-GRLS4-TR)
• SOP-8 package

Typical applications

• TV monitor backlighting
• Automotive
• LED lighting
• Notebook
• Street lamp

More information

• Datasheet