AS-Interface Slave IC

AS2702 (SAP4.1)

Rev. C, January 2001

Page 7 of 18

with VSIG > 3V, VUOUT may drop as much as 1V below it’s level

in unloaded condition

2

Electrolythic and rf filter capacitor in parallel

I1RP9SRZHUVXSSO\RXWSXW85

The voltage at U5R is derived from the voltage present at UOUT, as long as UOUT is not

switched off due to overload. In the latter case U5R is derived from an alternative voltage out

of the UOUT voltage regulator, which is more or less similar to VUOUT in non switched off

condition of UOUT. As a result VU5R is not affected by overload condition at UOUT and will

remain.

6\PERO

3DUDPHWHU

PLQ

PD[

8QLW

VU5R

Power supply output voltage

4.85

5.15

V

IU5R

Load current

1

mA

CU5R

Buffer capacitor

100

nF

J2VFLOODWRUSLQV26&DQG26&

The only component to be connected to these pins is a quartz crystal with a resonance fre-

quency of 5.333333 MHz (AS-Interface quartz crystal).

6\PERO

3DUDPHWHU

PLQ

PD[

8QLW

CX2

Stray capacitance

10

pF

K'DWDSRUWSLQV'«'DQGGDWDVWUREHSLQ'67%Q

Basically data port D3, …, D0 is designed for bidirectional data transfer out of and into the

slave device. Each data port pin is equipped with both a low-side open-drain output stage as

well as an input stage to this purpose.

Depending on the so called IO-configuration code, written into and stored in the slave device,

each data port pin is individually set to behave as

• output, or

• output / input, or

• input.

The timing of the data transfer is presented in fig. 2.

Strobe signal DSTBn flags and governs the data transfer as follows:

ha) data port pin is set ‘output’:

output data become valid upon the HL-edge of the strobe and will remain so until the next

HL-edge, hence during the entire strobe cycle;

hb) data port pin is set ‘output / input’:

output data become valid upon the HL-edge of the strobe and will remain so until it’s LH-

edge; input data to be valid within a specific time window relative to the HL-edge, after

completion of the strobe’s L-phase;

hc) data port pin is set ‘input’: