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AS1110

Datasheet - Detailed Descr i p ti on

8 Detailed Description

The AS1110 is designed to drive up to 16 LEDs through a fast serial interface and 16 constant-current output drivers. Furthermore, the AS1110

provides diagnostics for detecting open- or shorted-LEDs, as well as over-temperature conditions for LED display systems, especially LED traffic

sign applications.

The AS1110 contains an 16-bit shift register and an 16-bit data register, which convert serial input data into parallel output format. At AS1110

output stages, sixteen regulated current sinks are designed to provide uniform and constant current with excellent matching between ports for

driving LEDs within a wide range of forward voltage variations. External output current is adjustable from 0.5 to 100mA using an external resistor

for flexibility in controlling the brightness intensity of LEDs. The AS1110 guarantees to endure 15V maximum at the outputs.

The serial interface is capable of operating at a minimum of 30 MHz, satisfying the requirements of high-volume data transmission.

Using a multiplexed input/output technique, the AS1110 adds additional functionality to pins SDO, LD and OEN. These pins provide highly useful

functions (open- and shorted-LED detection, over-temperature detection), thus reducing pin count. Over-temperature detection will work on-the-

run, whereas the open- and shorted-LED detection can be used on-the-run or in low-current diagnostic mode (see page 15).

Figure 8. AS1110 - Block Diagram

8.1 Serial Interface

Data accesses are made serially via pins SDI and SDO. At each CLK rising edge, the signal present at pin SDI is shifted into the first bit of the

internal shift register and the other bits are shifted ahead of the first bit. The MSB is the first bit to be clocked in. In error-detection mode the shift

register will latch-in the corresponding error data of temperature-, open-, and short-error register with each falling edge of LD.

AS1110

REXT

OEN

CLK

SDI

LD

Current

Generators

Detailed

Error

Detection

16-Bit Data

Register

16-Bit Shift

Register

Temperature

Detection

16-Bit Open

Detection & Error

Register

16-Bit Short

Detection & Error

Register

Global Error

Detection

SDO

Indicates 16 Bit Path

Control Logic