MAX1272 Datasheet, PDF (9/20 Pages) Maxim Integrated Products – Fault-Protected, 12-Bit ADCs with Software-Selectable Input Range

Fault-Protected, 12-Bit ADCs
with Software-Selectable Input Range
DIN DOUT CS
SCLK
V_DD
GND
MAX1272
MAX1273
SERIAL INTERFACE
LOGIC
OUT
AIN
SIGNAL
CONDITIONING
T/H
12-BIT
IN
SAR ADC
CLK
REF
REF
4.096V
REFERENCE
Figure 2. Simplified Block Diagram
Table 1. Control-Byte Format
BIT 7
(MSB)
START
BIT 6
RNG
BIT 5
BIP
BIT 4
PD
Bit 3
MODE1
BIT 2
MODE0
BIT 1
RESERVED
BIT 0
(LSB)
REF
BIT
7 (MSB)
6
5
4
3
2
1
0 (LSB)
NAME
START
RNG
BIP
PD
MODE1
MODE0
RESERVED
REF
DESCRIPTION
Write a logic 1 (see the Input Data Format section)
Selects the full-scale input voltage range (Tables 2, 3)
Selects unipolar or bipolar conversion mode (Tables 2, 3)
Selects normal operation (PD = 1) or power-down (PD = 0) mode
Selects standby power-down (STBYPD) or full power-down (FULLPD) mode (Table 4)
Selects delayed or immediate power-down mode (Table 4)
Write a logic 0
Selects external (REF = 0, default) or internal (REF = 1) reference mode
Input Range and Protection
The MAX1272/MAX1273 provide software-selectable
analog input voltage ranges. Program the analog input
to one of four ranges by setting the appropriate control
bits (RNG, BIP) in the control byte (Table 1). The
MAX1272 has selectable input voltage ranges extend-
ing to ±10V (±V_REF ✕ 2.4414), while the MAX1273 has
selectable input voltage ranges extending to ±V_REF.
Figure 3 shows the equivalent input circuit.
Overvoltage circuitry at the analog input provides ±12V
fault protection for the MAX1272. This circuit limits the
current going into or out of the device to less than 2mA,
providing an added layer of protection from momentary
over/undervoltages at the analog input. The overvoltage
protection activates when the device enters power-
down mode or if V_DD = 0.
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