The FAN5607, a parallel, constant-current LED driver features an adaptive charge pump that allows the driver to generate a regulated output current from a battery with an input voltage between 2.4V to 5.5V, while achieving up to 92% peak efficiency.

A proprietary internal circuitry continuously monitors each LED current loop and automatically adjusts the generated output DC voltage to the lowest minimum value required by the LED having the highest forward voltage. This adaptive nature of the FAN5607 eliminates the need for LED pre-selection (matching). The driver’s built-in auto-sense circuitry ensures the same high efficiency regardless of the number of LEDs.

When the input voltage is sufficiently high to sustain the programmed current level in the LEDs, the FAN5607 re-configures itself to operate as a linear regulator, and the DC-DC converter is turned off. An external resistor can be used to program the LED current. The resistor sets the maximum LED current and a PWM signal applied to the enable pin can modulate that current level between 0mA (off) and the maximum level.

The FAN5607 is available in a 4x4mm 16-lead MLP package. For pricing and availability information, visit www.fairchildsemi.com/pf/FA/FAN5607.html. A FAN5607 demo board is also available. Please contact your local sales representative for more information.

Features
- Parallel LED driver supports all forward voltages
- Adaptive V OUT adjustment to the highest diode voltage
- Internally-matched LED current sources
- Built-in charge pump has three modes of operation: 1X, 1.5X, and 2X mode
- Up to 92% efficiency
- Low EMI, low ripple
- Up to 120mA output current (4 x 30mA)
- Uses external resistor to set maximum (100%) LED current
- Enable input can be Duty-Cycle-Modulated to control LED current level between 0 and 100%
- 2.4V to 5.5V input voltage range
- I_CC < 1µA in shutdown mode
- 1MHz operating frequency
- Shutdown isolates output from input
- Soft-start limits inrush current
- Short circuit protection
- Minimal external components needed
- Available in a 4x4mm 16-lead MLP package

Applications
- Cell phones
- Handheld computers