Datasheet

Reference Selection
Select between internal and external voltage modes
through bit REF of the configuration byte. Set REF = 1 for
internal reference mode and REF = 0 for external refer-
ence mode.
Internal Reference
The MAX1098 has a 2.50V internal reference, while the
MAX1099 has a 1.20V internal reference. Both are fac-
tory trimmed for accuracy. When internal reference is
selected, REF can be used to drive an external load with
100μA capability. Bypass REF to GND with a 0.1μF mini-
mum capacitance. Wake-up time is C x 2.5 x 10
4
s for the
MAX1098 and C x 1.2 x 10
4
s for the MAX1099.
External Reference
The MAX1098 can directly accept reference voltages at
REF from 0.8V to 2.5V, while the MAX1099 can directly
accept reference voltages from 0.8V to 1.2V. Bypass REF
to GND with a 0.1μF capacitor. Temperature measure-
ments always use internal reference.
Power Modes
The MAX1098/(MAX1099) typically requires supply cur-
rents of 380μA (350μA) or 310μA (280μA) when performing
voltage conversions at 100% duty cycle with internal or
external references, respectively. The difference reflects
Figure 6. Detailed SSTRB Timing
Table 1. Configuration-Byte Format
Table 2. Conversion-Byte Format
BIT 7
(MSB)
BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1
BIT 0
(LSB)
Start 0 0 0 0 PM1 PM0 REF
BIT NAME DESCRIPTION
7 (MSB) Start
First logic 1 after CS goes low. (See Input Data Format.)
6, 5, 4, 3 Must be 0000 to load a conguration byte.
2, 1 PM1, PM0 These 2 bits select the desired power mode (Table 3).
0 REF
A logic high enables the internal reference. A logic low disables the internal reference and selects
the external reference mode.
BIT 7
(MSB)
BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1
BIT 0
(LSB)
Start 0 1 0 SEL3 SEL2 SEL1 SEL0
BIT NAME DESCRIPTION
7 (MSB) Start
First logic 1 after CS goes low. (See Input Data Format.)
6, 5, 4 Must be 010 to load a conversion byte.
3, 2, 1, 0
SEL3, SEL2,
SEL1, SEL0
These 4 bits select the input conguration (Table 4).
t
CSH
t
DO
t
SSTRB
t
CONV
t
SCK
t
CSS
CSB
SSTRB
SCLK
DOUT
PDO CLOCKED IN
SSTRB TIMING
MAX1098/MAX1099 10-Bit Serial-Output Temperature Sensors
with 5-Channel ADC
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