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AS1105

Data Sheet - D e t a i l e d D e s c r i p t i o n

8 Detailed Description

Serial-Addressing Modes

The 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 4. 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 5.

Figure 5. Timing Diagram

Digit and Control Registers

The AS1105 incorporates 12 registers, which are listed in Table 5. 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

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.

Table 4. Serial Data Format (16 Bits)

D15

D14

D13

D12

D11

D10

D9

D8

D7

D6

D5

D4

D3

D2

D1

D0

X

X

X

X

Address

MSB

Data

LSB

D0

D1

D15

D14

DOUT

DIN

CLK

LOAD