Datasheet

Digital Interface
The MAX1302 features a serial interface that is compat-
ible with SPI/QSPI and MICROWIRE devices. DIN,
DOUT, SCLK, CS, and SSTRB facilitate bidirectional
communication between the MAX1302 and the master
at SCLK rates up to 10MHz (internal clock mode,
mode 2), 3.67MHz (external clock mode, mode 0), or
4.39MHz (external acquisition mode, mode 1). The
master, typically a microcontroller, should use the
CPOL = 0, CPHA = 0, SPI transfer format, as shown in
the timing diagrams of Figures 2, 3, and 4.
The digital interface is used to:
• Select single-ended or true-differential input channel
configurations
• Select the unipolar or bipolar input range
• Select the mode of operation:
External clock (mode 0)
External acquisition (mode 1)
Internal clock (mode 2)
Reset (mode 4)
Partial power-down (mode 6)
Full power-down (mode 7)
• Initiate conversions and read results
Chip Select (CS)
CS enables communication with the MAX1302. When CS
is low, data is clocked into the device from DIN on the ris-
ing edge of SCLK and data is clocked out of DOUT on
the falling edge of SCLK. When CS is high, activity on
SCLK and DIN is ignored and DOUT is high impedance
allowing DOUT to be shared with other peripherals.
SSTRB is never high impedance and therefore cannot be
shared with other peripherals.
Serial Strobe Output (SSTRB)
As shown in Figures 3 and 4, the SSTRB transitions high
to indicate that the ADC has completed a conversion
and results are ready to be read by the master. SSTRB
remains low in the external clock mode (Figure 2) and
consequently may be left unconnected. SSTRB is dri-
ven high or low regardless of the state of CS, therefore
SSTRB cannot be shared with other peripherals.
MAX1302
8-Channel, ±V
REF
Multirange Inputs,
Serial 16-Bit ADC
______________________________________________________________________________________ 19
001 010 011 100 101 110 111
0
-V
REF
/2
-V
REF
+V
REF
+V
REF
/2
+V
REF
/4
-V
REF
/4
EACH INPUT IS FAULT TOLERANT TO ±6V.
(CH_) - AGND1 (V)
INPUT RANGE SELECTION BITS, R[2:0]
FSR = V
REF
/ 2
FSR = V
REF
/ 2
FSR = V
REF
/ 2
FSR = V
REF
FSR = V
REF
FSR = V
REF
FSR = 2 x V
REF
+
3
/
4
V
REF
-
3
/
4
V
REF
Figure 7. Single-Ended Input Voltage Ranges
001 010 011 100 101 110 111
-V
REF
-2 x V
REF
+2 x V
REF
+V
REF
+V
REF
/2
-V
REF
/2
EACH INPUT IS FAULT TOLERANT TO ±6V.
(CH_+) - (CH_-) (V)
INPUT RANGE SELECTION BITS, R[2:0]
0
FSR = V
REF
FSR = 2 x V
REF
FSR = 4 x V
REF
-
3
/
2
V
REF
+
3
/
2
V
REF
Figure 8. Differential Input Voltage Ranges