MAX6629_10 Datasheet, PDF (6/8 Pages) Maxim Integrated Products – 12-Bit + Sign Digital Temperature Sensors with Serial Interface

12-Bit + Sign Digital Temperature Sensors
with Serial Interface
t_CSS
CS
SCK
t_DV
t_DO
SO
D15
Figure 3. SPI Timing Diagram
t_TR
D3 D2 D1 D0
Table 1. Data Output Format
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2
D1
D0
Sign
MSB
Data
LSB
Data
Low
High-Z
High-Z
Table 2. Temperature Data Format
(Two’s Complement)
TEMPERATURE
(°C)
150
125
25
0.0625
0
-0.0625
-25
-55
DIGITAL OUTPUT (BINARY)
D15–D3
D2
D1, D0
0,1001,0110,0000
0
XX
0,0111,1101,0000
0
XX
0,0001,1001,0000
0
XX
0,0000,0000,0001
0
XX
0,0000,0000,0000
0
XX
1,1111,1111,1111
0
XX
1,1110,0111,0000
0
XX
1,1100,1001,0000
0
XX
finish. CS’s falling edge stops any conversion in
progress, and data is latched into the shift register.
Then the data clocks out at SO on SCK’s falling edge
with the sign bit (D15) first, followed by the MSB. Data
is sent in one 16-bit word, and CS must remain low until
all 16 bits are transferred. If CS goes high in the middle
of a transmission, it is necessary to wait the conversion
time (less than 300ms) before attempting a new read.
The serial data is composed of 12 + 1 data bits
(D15–D3) and 3 trailing bits (D2–D0). D2 is always low,
serving as the confirmation bit that the device has been
communicated with. The last 2 bits, D0 and D1, are
undefined and are always in high-impedance mode
(Table 1). The power-up state for SO is high imped-
ance. Figure 3 shows the detailed serial timing specifi-
cations for the SPI port. The temperature data format is
in two's complement format (Table 2).
Power Shutdown Mode
The MAX6629–MAX6632 do not have a built-in power
software shutdown mode. However, a power shutdown
mode is easily implemented utilizing an unused logic
gate. A typical CMOS or TTL logic output has enough
drive capability to serve as the power source if its out-
put voltage level exceeds 3V, as shown in Figure 1.
Drive the logic output low to provide a hardware shut-
down mode.
Idle Mode
The MAX6629–MAX6632 can be put into idle mode by
pulling CS low. Data can be clocked out when the
device is in idle mode.
Power-On Reset (POR)
The POR supply voltage of the MAX6629–MAX6632 is
typically 1.6V. Below this supply voltage, the interface
is inactive and the data register is set to the POR state,
0°C.
When power is first applied and V_CC rises above 1.6V
(typ), the device starts to convert, although temperature
reading is not recommended at V_CC levels below 3.0V.
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