UM0425 Datasheet, PDF (1/11 Pages) STMicroelectronics – STLED316S Front panel LED controller/driver

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:
■ External discrete current driver
■ Current limiting resistors
■ Additional cost of crystal for MCU clock
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.
June 2007
Rev 1
1/11
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