MAX1329BETL+ Maxim Integrated Products, MAX1329BETL+ Datasheet - Page 38

• Manufacturer Part Number: MAX1329BETL+
• Description: IC DAS 12BIT 300KSPS 40-TQFN-EP
• Manufacturer: Maxim Integrated Products

Specifications of MAX1329BETL+

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

12-/16-Bit DASs with ADC, DACs, DPIOs, APIOs,
Reference, Voltage Monitors, and Temp Sensor
See Figure 21 for performing an ADC conversion using
a DPIO input programmed as CONVST. Allow at least
600ns for acquisition while the DPIO input is low and
the acquisition ends on the rising edge of the DPIO.
The conversion requires an additional 14 ADC clock
cycles. If the PGA gain is set to 4 or 8, the minimum
acquisition time is 1.2µs due to the increase of the input
sampling capacitor.
The MAX1329/MAX1330 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 tem-
perature calculations:
where:
V
(I
V
(I
Figure 22. Temperature-Conversion Timing
38
HIGH
HIGH
LOW
LOW
CS
temperature
______________________________________________________________________________________
)
)
= sensor-diode voltage with low current flowing
(SCLK, DIN, DOUT NOT SHOWN)
= sensor-diode voltage with high current flowing
TEMP CONVERT COMMAND
ADC MODE
=
(
V
Temperature Measurement
HIGH
START
-
V
LOW
)
WAIT PERIOD
93.5 CLOCKS
x
n x ln
THERE ARE TWO ADC CONVERSIONS PER TEMPERATURE CONVERSION.
⎡
⎢
⎣
q
k
I
I
LOW
1 CLOCK = 1/(ADC MASTER CLOCK FREQUENCY)
High
⎤
⎥
⎦
1ST AQUISITION
90 CLOCKS
TRACK
q = charge of electron = 1.602
k = Boltzman constant = 1.38
n = ideality factor (slightly greater than 1)
The temperature measurement process is fully automat-
ed in the MAX1329/MAX1330. All steps are sequenced
and executed by the MAX1329/MAX1330 each time an
input channel (or an input channel pair) configured for
temperature measurement is scanned.
The resulting 12-bit, two’s complement number repre-
sents the sensor temperature in degrees Celsius, with
1 LSB = +0.125°C. Figure 22 shows the timing for a
temperature measurement.
An external 2.500V reference can be applied to
REFADJ, provided the internal reference is disabled
first. Use the temperature correction equation to obtain
the correct temperature:
Use the following equation when using the internal ref-
erence:
T
ACT
=
T
1ST CONVERSION
MEAS
19 CLOCKS
T
CONVERT
ACT
+
= 0.997 x T
(
T
MEAS
+
2ND AQUISITION
270 63
87 CLOCKS
TRACK
MEAS
✕
✕
.
10
10
-23
) (
- 0.91°C
× −
-19
J/K
1
coulombs
V
2ND CONVERSION
2 500
R R EFADJ
.
17.5 CLOCKS
CONVERT
V
STOP
)°
C