June 2007

Rev 1

1/11

UM0425

User manual

STLED316S Front panel LED controller/driver

evaluation board

Introduction

LED displays are widely used on consumer electronics and household appliances. Both

push button keys and LED displays form the front panel of these products.

Figure 1.

Typical front panel application

In conventional systems, a sub MCU (Microcontroller) is used to control the front panel

functions. Depending on the number of LED digit/segment and push button keys, an MCU

with a high pin count might be required.

Other disadvantages of an MCU solution:

The STLED316S is a complete front panel LED controller/driver that is able to solve these

disadvantages.

A common anode LED driver can drive 40 mA of current on each segment output. No

current limiting resistor is required as the current is set by a single RSET resistor. It has the

additional advantage of brightness control up to 8 increments. Display brightness can be

adjusted by modifying the brightness register value. It also has the capability of controlling

each 7-segment LED digit and discrete LED brightness individually.

The device can handle a maximum of 16 front panel keys. If any front panel key event is

detected, IRQ out is asserted. IRQ is released once the key data is read.

Current matching on each segment is guaranteed to be within 3%. When no digit and

segment are ON, STLED consumes much less current of around 200 µA which is achieved

by turning OFF internal current mirror circuitry.

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