W40S11-02
a default logic 1. All bus devices generally have logic inputs to
receive data.
How To Use the Serial Data Interface
Electrical Requirements
Although the W40S11-02 is a receive-only device (no data
write-back capability), it does transmit an “acknowledge” data
pulse after each byte is received. Thus, the SDATA line can
both transmit and receive data.
Figure 1 illustrates electrical characteristics for the serial
interface bus used with the W40S11-02. Devices send data
over the bus with an open drain logic output that can (a) pull
the bus line LOW, or (b) let the bus default to logic 1. The
pull-up resistor on the bus (both clock and data lines) establish
The pull-up resistor should be sized to meet the rise and fall
times specified in AC parameters, taking into consideration
total bus line capacitance.
VDD
VDD
~ 2k
:
~ 2k:
SERIAL BUS DATA LINE
SERIAL BUS CLOCK LINE
SDCLK
SDATA
SCLOCK
SDATA
CLOCK IN
DATA IN
CLOCK IN
DATA IN
DATA OUT
N
N
N
CLOCK OUT
DATA OUT
CHIP SET
(SERIAL BUS MASTER TRANSMITTER)
CLOCK DEVICE
(SERIAL BUS SLAVE RECEIVER)
Figure 1. Serial Interface Bus Electrical Characteristics
Rev 1.0,Dec. 01, 2006
Page 4 of 9
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