ACS8520T Semtech, ACS8520T Datasheet - Page 50

• Manufacturer Part Number: ACS8520T
• Description: Synchronous Equipment Timing Source (SETS) for Stratum 3/4E/4 and SMC Systems
• Manufacturer: Semtech

Serial Mode
In SERIAL Mode, the device is configured to interface with a serial microprocessor bus. Figure 19 and Figure 20 show
the timing diagrams of read and write accesses for this mode. The serial interface can be SPI compatible.
The Motorola SPI convention is such that address and data is transmitted and received MSB first. On the ACS8520,
device address and data are transmitted and received LSB first. Address, read/write control and data on the SDI pin
is latched into the device on the rising edge of the SCLK. During a read operation, serial data output on the SDO pin
can be read out of the device on either the rising or falling edge of the SCLK depending on the logic level of CLKE (note
CLKE=A(1)). For standard Motorola SPI compliance, data should be clocked out of the SDO pin on the rising edge of
the SCLK so that it may be latched into the microprocessor on the falling edge of the SCLK.
The serial interface clock (SCLK) is not required to run between accesses (i.e., when CSB = 1).
Figure 19 Read Access Timing in SERIAL Mode
Table 27 Read Access Timing in SERIAL Mode (For use with Figure 19)
Revision 3.02/October 2005 © Semtech Corp.
ADVANCED COMMUNICATIONS
Symbol
t
t
t
t
su1
su2
d1
d2
Setup SDI valid to SCLK
Setup CSB
Delay SCLK
Delay CSB
CSB
ALE=SCLK
A(0) = SDI
AD(0)=SDO
CSB
ALE=SCLK
A(0)=SDI
AD(0)=SDO
rising edge
falling edge
t
rising edge
su1
A(1) = CLKE = 0; SDO data is clocked out on the rising edge of SCLK
A(1) = CLKE = 1; SDO data is clocked out on the falling edge of SCLK
t
su2
Output not driven, pulled low by internal resistor
Output not driven, pulled low by internal resistor
R/W
R/W
to SDO high-Z
_
_
to SCLK
(SCLK
A0 A1 A2 A3 A4 A5 A6
A0 A1 A2 A3 A4 A5 A6
rising edge
t
h1
falling edge
rising edge
Parameter
t
pw1
for CLKE = 1) to SDO valid
t
pw2
FINAL
Page 50
D0 D1 D2 D3 D4 D5 D6 D7
t
d1
D0 D1 D2 D3 D4 D5 D6 D7
t
d1
14 ns
4 ns
MIN
-
-
F8530D_013ReadAccSerial_02
ACS8520 SETS
t
h2
TYP
t
h2
t
-
-
-
-
d2
t
d2
DATASHEET
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18 ns
16 ns
MAX
-
-