Rainbow Electronics MAX5133 - Manual (Page 12)

MAX5132/MAX5133
+5V/+3V, 13-Bit, Serial, Force/Sense DACs
with 10ppm/°C Internal Reference
12 ______________________________________________________________________________________
Serial-Interface Configuration
(SPI/QSPI/MICROWIRE/PIC16/PIC17)
The MAX5132/MAX5133 3-wire serial interface is com-
patible with SPI, QSPI, PIC16/PIC17 (Figure 4) and
MICROWIRE (Figure 5) interface standards. The 2-
byte-long serial input word contains three control bits
and 13 data bits in MSB-first format (Table 2).
The MAX5132/MAX5133’s digital inputs are double
buffered, which allows the user to:
•
load the input register without updating the DAC
register,
•
update the DAC register with data from the input
register,
•
update the input and DAC registers concurrently.
The 16-bit input word may be sent in two 1-byte pack-
ets (SPI-, MICROWIRE- and PIC16/PIC17-compatible),
with CS low during this period. The control bits C2, C1,
and C0 (Table 1) determine:
•
the clock edge on which DOUT transitions,
•
the state of the user-programmable logic output,
•
the configuration of the device after shutdown.
The general timing diagram in Figure 6 illustrates how
data is acquired. CS must be low for the part to receive
data. With CS low, data at DIN is clocked into the regis-
ter on the rising edge of SCLK. When CS transitions
high, data is latched into the input and/or DAC registers,
depending on the setting of the three control bits C2,
C1, and C0. The maximum serial-clock frequency guar-
anteed for proper operation is 10MHz for the MAX5132
and 6.6MHz for the MAX5133. Figure 7 depicts a more
detailed timing diagram of the serial interface.
Table 1. Serial-Interface Programming Commands
X = Don’t care
DIN
SCLK
CS
MOSI
SCK
I/O
SPI/QSPI
PORT
(PIC16/PIC17)
SS
V DD
CPOL = 0, CPHA = 0
(CKE = 1, CKP = 0, SMP = 0,
SSPM3 - SSPMO = 0001) ( ) PIC16/PIC17 ONLY
MAX5132
MAX5133
Figure 4. SPI/QSPI Interface Connections (PIC16/PIC17)
DIN
SCLK
CS
SK
SO
I/O
MICROWIRE
PORT MAX5132
MAX5133
Figure 5. MICROWIRE Interface Connections
D12 ............... D0
FUNCTION
C2 C0 C1
1 1 1 00XXXXXXXXXXX Mode 0: DOUT clocked out on SCLK’s falling edge (default).
1 XXXXXXXXXXXXX Shutdown DAC (provided PDL = 1).
16-BIT SERIAL WORD
0 XXXXXXXXXXXXX No operation.
1 XXXXXXXXXXXXX UPO goes high. 0
1
1
1 1 1XXXXXXXXXXXX Mode 1: DOUT clocked out on SCLK’s rising edge.
1
0
0
0 1 XXXXXXXXXXXXX UPO goes low (default).
0 13-Bit DAC Data Simultaneously load input and DAC registers; exit shutdown. 0
1
1
1 0 XXXXXXXXXXXXX Update DAC register from input register; exit shutdown.
0
1
0
0 0 13-Bit DAC Data Load input register; DAC register unchanged.