隆 Semiconductor
MSM7705-01/02/03
APPLICATION INFORMATION
DOUT Pull-up Resistor
A value of the pull-up resistor for the DOUT pin should be determined depending on frequencies
of BCLK and load capacitance.
If a smaller value is used, there may be some degradation in noise performance, resulting in an
increase in supply current.
Equation to give pull-up resistor
1
鈥斺€斺€斺€?鈥?50 ns
4
樓
f
BCLK
Rpull = 鈥斺€斺€斺€斺€斺€斺€斺€?(W)
C
L
where
f
BCLK
= Frequency of BCLK
C
L
= Load capacitance of the PCMOUT pin
(approximately 20 pF for a CMOS or TTL load)
50 ns = Internal delay of the MSM7705
Condition for Calculation
If data is turned back from DOUT to DIN under the condition the SYNC signal and BCLK signal
rise simultaneously, the data can normally be transferred.
X, RSYNC
BCLK
T
T = Rpull
樓
C
L
DOUT
16/20