MAX1153_10 Datasheet, PDF (23/30 Pages) Maxim Integrated Products – Stand-Alone, 10-Channel, 10-Bit System Monitors with Internal Temperature Sensor and VDD Monitor

Stand-Alone, 10-Channel, 10-Bit System Monitors
with Internal Temperature Sensor and V_DD Monitor
execute a manual conversion. See Figure 9 for manual
conversion timing:
1) Disable autoscan (set up register scan mode bit to
zero), if necessary.
2) Pull CS low.
3) Initiate a conversion by issuing a Manually
Triggered Conversion command (0000, followed by
the address bits of the channel to be converted).
4) Pull CS high to start the conversion.
5) Maintain a logic high on CS to allow for reference
power-up (if the reference mode requires it) and
conversion time.
6) Pull CS low.
7) Issue a Read Current Data Register for Selected-
Channel command (0010, followed by the same
address of the channel in the Manually Triggered
Conversion command).
Voltage Measurements
Every voltage measurement (internal V_DD or external
input channel) requires 10.6µs to complete. If the inter-
nal reference needs to power up (reference mode =
01), an additional 40µs is required every time the
MAX1153/MAX1154 come out of automatic shutdown
mode after a sample wait period greater than 80µs.
Monitoring V_DD
This internal acquisition channel samples and converts
the supply voltage, V_DD.
V_DD value can be calculated from the digitized data
with the following equation:
V_DD
=
2
x
(current
_
data
_
register
_
content)
x
⎛
⎝⎜
V_REF
1024
⎞
⎠⎟
The reference voltage must be larger than 1/2V_DD for
the operation to work properly. V_DD monitoring requires
10.6µs (typ) per measurement.
Temperature Measurement
The MAX1153/MAX1154 perform temperature measure-
ment by measuring the voltage across a diode-con-
nected transistor at two different current levels. The
following equation illustrates the algorithm used for
temperature calculations:
q
temperature
=
(V_HIGH
−
V_LOW)
x
n
x
ln
k
⎡ IHigh ⎤
⎣⎢^ILOW ⎦⎥
t_PU+CONV
CS
SCLK
DIN
C3 C2 C1 C0 A3 A2 A1 A0
DOUT
C3 C2 C1 C0 A3 A2 A1 A0
Figure 9. Manual Conversion Timing Without Reading Data
______________________________________________________________________________________ 23