MAX11600 Datasheet, PDF (15/23 Pages) Maxim Integrated Products – 2.7V to 3.6V and 4.5V to 5.5V, Low-Power, 4-/8-/12-Channel 2-Wire Serial 8-Bit ADCs

2.7V to 3.6V and 4.5V to 5.5V, Low-Power,
4-/8-/12-Channel 2-Wire Serial 8-Bit ADCs
Table 2. Configuration Byte Format
BIT 7
(MSB)
REG
BIT 6
SCAN1
BIT 5
SCAN0
BIT 4
CS3
BIT 3
CS2
BIT 2
CS1
BIT 1
CS0
BIT 0
(LSB)
SGL/DIF
BIT
NAME
DESCRIPTION
7
REG
Register bit. 1 = setup byte (Table 1), 0 = configuration byte.
6
SCAN1
Scan select bits. Two bits select the scanning configuration (Table 5). Default to 00 at
5
SCAN0
power-up.
4
CS3
3
CS2
Channel select bits. Four bits select which analog input channels are to be used for conversion
(Tables 3 and 4). Default to 0000 at power-up. For the MAX11600/MAX11601, CS3 and CS2 are
2
CS1
internally set to 0. For the MAX11602/MAX11603, CS3 is internally set to zero.
1
CS0
0
SGL/DIF
1 = single-ended, 0 = pseudo-differential (Tables 3 and 4). Default to 1 at power-up (see the
Single-Ended/Pseudo-Differential Input section).
Applications Information ^{Automatic shutdown results in dramatic power savings,}
particularly at slow conversion rates. For example, at a
Power-On Reset conversion rate of 10ksps, the average supply current
The configuration and setup registers (Tables 1 and 2) for the MAX1036 is 8µA and drops to 2µA at 1ksps.
default to a single-ended, unipolar, single-channel con- At 0.1ksps the average supply current is just 1µA (see
version on AIN0 using the internal clock with V_DD as the Average Supply Current vs. Conversion Rate in the
reference and AIN_/REF (MAX11600/MAX11601/ Typical Operating Characteristics section).
MAX11604/MAX11605) configured as an analog input.
For the MAX11602/MAX11603, the REF pin is floating
after power-up. The RAM contents are unknown after
power-up.
Reference Voltage
SEL[2:0] of the setup byte (Table 1) controls the refer-
ence and the AIN_/REF (MAX11600/MAX11601/
MAX11604/MAX11605) or REF (MAX11602/MAX11603)
Automatic Shutdown configuration (Table 6). When AIN_/REF (MAX11600/
SEL[2:0] of the setup byte (Tables 1 and 6) controls the MAX11601/MAX11604/MAX11605) is configured to be
state of the reference and AIN_/REF (MAX11600/ a reference input or reference output (SEL1 = 1), con-
MAX11601/MAX11604/MAX11605) or REF (MAX11602/ versions on AIN_/REF appear as if AIN_/REF is con-
MAX11603). If automatic shutdown is selected (SEL[2:0] = nected to GND (see note 2 of Tables 3 and 4).
100), shutdown occurs between conversions when the
MAX11600–MAX11605 are idle. When operating in exter-
nal clock mode, a STOP condition must be issued to place
the devices in idle mode and benefit from automatic shut-
down. A STOP condition is not necessary in internal clock
mode to benefit from automatic shutdown because power-
down occurs once all contents are written to memory
(Figure 10). All analog circuitry is inactive in shutdown and
supply current is less than 1µA. The digital conversion
results are maintained in RAM during shutdown and are
available for access through the serial interface at any
time prior to a STOP or repeated START condition.
When idle, the MAX11600–MAX11605 wait for a START
condition followed by their slave address (see the
Slave Address section). Upon reading a valid address
byte, the MAX11600–MAX11605 power up. The analog
circuits do not require any wakeup time from shutdown,
whether using external or internal reference.
Internal Reference
The internal reference is 4.096V for the MAX11600/
MAX11602/MAX11604 and 2.048V for the MAX11601/
MAX11603/MAX11605. SEL1 of the setup byte controls
whether AIN_/REF (MAX11600/MAX11601/MAX11604/
MAX11605) is used for an analog input or a reference
(Table 6). When AIN_/REF (MAX11600/MAX11601/
MAX11604/MAX11605) or REF (MAX11602/MAX11603) is
configured to be an internal reference output (SEL[2:1] =
11), decouple AIN_/REF (MAX11600/MAX11601/
MAX11604/MAX11605) or REF (MAX11602/MAX11603)
to GND with a 0.01µF capacitor. Due to the decoupling
capacitor and the 675Ω reference source impedance,
allow 80µs for the reference to stabilize during initial
power-up. Once powered up, the reference always
remains on until reconfigured. The reference should not
be used to supply current for external circuitry. When the
MAX11602/MAX11603 is in shutdown, the internal refer-
ence output is in a high-impedance state.
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