Datasheet

AD5162
Rev. C | Page 16 of 20
SPI INTERFACE
SPI-COMPATIBLE, 3-WIRE SERIAL BUS
The AD5162 contains a 3-wire, SPI-compatible digital interface
(SDI,
CS
, and CLK). The 9-bit serial word must be loaded MSB
first. The format of the word is shown in Table 8.
The positive-edge sensitive CLK input requires clean transitions
to avoid clocking incorrect data into the serial input register.
Standard logic families work well. If mechanical switches are
used for product evaluation, they should be debounced by a
flip-flop or another suitable means. When
CS
is low, the clock
loads data into the serial register on each positive clock edge
(see Figure 42).
The data setup and data hold times in Table 3 determine the
valid timing requirements. The AD5162 uses a 9-bit serial input
data register word that is transferred to the internal RDAC
register when the
CS
line returns to logic high. Extra MSB bits
are ignored.
Table 8. Serial Data-Word Format
1
MSB LSB
B8 B7 B6 B5 B4 B3 B2 B1 B0
A0 D7 D6 D5 D4 D3 D2 D1 D0
(2
8
) (2
7
) (2
0
)
1
The values of bits are shown in parentheses.
SDI
CLK
CS
V
OUT
RDAC REGISTER LOAD
A0 D7 D6 D5 D4 D3 D2 D1 D0
0
1
0
1
0
0
1
1
04108-0-042
Figure 42. SPI Interface Timing Diagram
(V
A
= 5 V, V
B
= 0 V, V
W
= V
OUT
)
t
CSH0
t
CSS
t
CL
t
CH
t
DS
t
CSW
t
S
t
CS1
t
CSH1
t
CH
CLK
CS
V
OUT
1
0
1
0
1
0
V
DD
0
±1LSB
SDI
(DATA IN)
Dx Dx
04108-0-043
Figure 43. SPI Interface Detailed Timing Diagram (V
A
= 5 V, V
B
= 0 V, V
W
= V
OUT
)