AS1108

4-Digit LED Display Driver

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1 General Description

The AS1108 is a compact display driver for 7-segment

numeric displays of up to 4 digits. The device can be

programmed via SPI, QSPI, and Microwire as well as a

conventional 4-wire serial interface.

The device includes an integrated BCD code-B/HEX

decoder, multiplex scan circuitry, segment and display

drivers, and a 32-bit memory. Internal memory stores

the LED settings, eliminating the need for continuous

device reprogramming.

Every segment can be individually addressed and

required to set the current through the LED display. LED

brightness can be controlled by analog or digital means.

The device can be programmed to use the internal

code-B/HEX decoder to display numeric digits or to

directly address each segment.

The AS1108 features an extremely low shutdown cur-

rent of typically 3µA, and an operational current of less

than 500µA. The number of digits can be programmed,

the device can be reset by software, and an external

clock is also supported. Additionally, segment blinking

can be synchronized across multiple drivers.

The AS1108 provides several test modes for easy appli-

cation debugging.

The device is available in a 20-pin DIP and a 20-pin

SOIC package.

Figure 1. Typical Application Diagram

2 Key Features

!

10MHz SPI-, QSPI-, Microwire-Compatible

Serial I/O

!

Individual LED Segment Control

!

Segment Blinking Control (can be synchronized

across multiple drivers)

!

Hexadecimal- or BCD-Code/No-Decode

Digit Selection

!

3µA Low-Power Shutdown Current (typ;

data retained)

!

Extremely Low Operating Current 0.5mA in

Open-Loop

!

Digital and Analog Brightness Control

!

Display Blanked on Power-Up

!

Drive Common-Cathode LED Displays

!

Supply Voltage Range: +2.7 to +5.5V

!

Software Reset

!

Optional External Clock

!

Packages:

- 20-pin DIP

- 20-pin SOIC

3 Applications

The AS1108 is ideal for bar-graph displays, instrument-

panel meters, LED matrix displays, dot matrix displays,

set-top boxes, white goods, professional audio equip-

ment, medical equipment, industrial controllers and

panel meters.

AS1108

4-Digit Microprocessor Display

DIG0 to

DIG3

SEG A to G

SEP DP

4 Digits

8 Segments

I/O

I/O

SCK

DIN

CLK

GND

GND

LOAD/CSN

+5V

9.53k

Ω

Micro-

processor