AS1105 데이터 시트보기 (PDF) - austriamicrosystems AG

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AS1105

Serially Interfaced, 4-Digit LED Driver

austriamicrosystems AG 

Data Sheet AS1105

LOAD

CLK

DIN

DOUT

Figure 1: Timing diagram

tDH

tDS

D15

tCL

tCH

D14

tCSW

tCS

tCP

tLDCK

D1

D0

tDO

D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0

XX X X

Address

MSB

Data

LSB

Table 1: Serial data format (16 bits)

Detailed Description

Serial-Addressing Modes

Programming of the AS1105 is done via the 4 wire serial

interface. A programming sequence consists of 16-bit

packages. The data is shifted into the internal 16 Bit

register with the rising edge of the CLK signal. With the

rising edge of the LOAD signal the data is latched into a

digital or control register depending on the address. The

LOAD signal must go to high after the 16th rising clock

edge. The LOAD signal can also come later but just before

the next rising edge of CLK, otherwise data would be lost.

The content of the internal shift register is applied 16.5

clock cycles later to the DOUT pin. The data is clocked out

at the falling edge of CLK. The Bits of the 16Bit-

programming package are described in table 1. The first 4

Bits D15-D12 are ”don’t care, D11-D8 contain the address

and D7-D0 contain the data. The first bit is D15, the most

significant bit (MSB). The exact timing is given in figure 1.

Digit and Control Registers

The AS1105 incorporates 12 registers, which are listed in

Table 2. The digit and control registers are selected via the

4Bit address word. The 4 digit registers are realized with a

32bit memory. Each digit can be controlled directly without

rewriting the whole contents. The control registers consist

of decode mode, display intensity, number of scanned

digits, shutdown, display test and reset/external clock

register.

Shutdown Mode

The AS1105 features a shutdown mode, where it consumes

only 20µA current. The shutdown mode is entered via a

write to register 0Ch. Then all segment current sources are

pulled to ground and all digit drivers are connected to VDD,

so that nothing is displayed. All internal digit registers keep

the programmed values. The shutdown mode can either be

used for power saving or for generating a flashing display

by repeatedly entering and leaving the shutdown mode. The

AS1105 needs typically 250µs to exit the shutdown mode.

During shutdown the AS1105 is fully programmable. Only

the display test function overrides the shutdown mode.

Initial Power-Up

After powering up the system all register are reset, so that

the display is blank. The AS1105 starts the shutdown mode.

All registers should be programmed for normal operation.

The default settings enable only scan of one digit, the

internal decoder is disabled, data register and intensity

register are set to the minimum value.

Revision 1.32, Oct. 2004

Page 4 of 12

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