High-Efficiency PWM LED Driver with Boost Converter and Five Constant-Current GPIO Ports

PWM-Capable Boost Maximizes Control and Efficiency for WLED Backlighting Applications


The MAX6948B general-purpose input/output (GPIO) peripheral drives a series string of white LEDs (WLEDs), and contains up to five general-purpose input/output (GPIO) ports to drive additional LEDs.

The integrated 2MHz boost converter minimizes the size and cost of external components and supplies 30mA of load current at up to 28V. The converter is stable under all load conditions from 5V up to 28V and includes open-circuit detection to prevent damage to the IC. An I²C-programmable 10-bit pulse-width modulation (PWM) signal enables 1024 levels of WLED intensity.

The five GPIO ports function as logic inputs, open-drain logic outputs, or constant-current sinks in any combination. Ports withstand 5.5V independent of the MAX6948B's supply voltage. Two of the ports drive additional LEDs up to 30mA/port, while the other three ports drive LEDs at up to 10mA/port. The MAX6948B features shutdown and standby modes for low-power dissipation. The constant-current drivers contain programmable PWM outputs and allow staggering to reduce the input peak-current requirements. The I/O ports also feature ramp-up and ramp-down controls.

The MAX6948B features a single input to select from four I²C slave addresses. Programming and functionality for the five GPIO ports is identical to the MAX6946/MAX6947 I/O expanders.

The MAX6948B is available in a 25-bump (2.31mm x 2.31mm) WLP package for cell phones, PDAs, and other portable consumer electronic applications. The MAX6948B operates over the -40°C to +105°C temperature range.
MAX6948B: Typical Operating Circuit MAX6948B: Typical Operating Circuit Enlarge+

Key Features

  • 28V Step-Up DC-DC Converter with Integrated nMOS Power Switch
    • Built-In 10-Bit PWM Control for Improved Efficiency
    • No Discharge Path During PWM Off Period for Increased Battery Life
    • Fixed 2MHz Switching for Smaller Components
    • Drives up to 6 Series WLEDs
  • ±8kV Human Body Model (HBM) ESD Protection for GPIOs and Boost-Converter Output
  • Five Open-Drain GPIOs Capable of Constant-Current LED Drive with Individual 8-Bit PWM Intensity Control
  • 2.7V to 5V Power-Supply Operation
  • Register Compatible with MAX6946/MAX6947 GPIO Port Expanders
  • 400kbps, 5.5V Tolerant I²C Interface
  • Four I²C Slave Address Choices
  • Active-Low RST Input Clears Serial Interface and Exits Shutdown (Reset-Run Option)
  • Small (2.31mm x 2.31mm) WLP Package


  • Cell Phones
  • Handheld Games
  • LED Backlighting for LCDs
  • PDAs
  • Portable Consumer Electronics
Part Number Battery Input Regulation Topology Max. No. of LEDs LED Channels LED Configuration ILED per Channel
Dimming Ratio Dimming Control POUT
LED String Volt.
Oper. Freq.
Package/Pins Budgetary
max max min max max max See Notes
MAX6948B  1-Cell Li+
Charge Pump
Inductor Based
11 6 Series-Parallel 0.03 85 I2C Serial 1.2 2.7 5 5.5 28 2000
$3.29 @1k
See All LED Drivers (66)
Pricing Notes:
This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific and version-specific prices and delivery, please see the price and availability page or contact an authorized distributor.

MAX6948EVKIT: Evaluation Kit for the MAX6948B

Technical Documents

App Note 5396 Dynamic Backlighting Improves Contrast Ratio and Trims Power for Small LCD Panels

Quality and Environmental Data

Request Reliability Report for: MAX6948B 
Lead-Free Package Tin (Sn) Whisker Reports

Related Resources