MAX11359AETL+ Maxim Integrated Products, MAX11359AETL+ Datasheet - Page 31

• Manufacturer Part Number: MAX11359AETL+
• Description: IC DAS SYSTEM 16BIT 40-TQFN
• Manufacturer: Maxim Integrated Products
• Type: Data Acquisition System (DAS)r

Specifications of MAX11359AETL+

• Resolution (bits): 16 b
• Sampling Rate (per Second): 477
• Data Interface: MICROWIRE™, QSPI™, Serial, SPI™
• Voltage Supply Source: Analog and Digital
• Voltage - Supply: 1.8 V ~ 3.6 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 40-TQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

For the two-current method, currents I
passed through a p-n junction. This requires two V
measurements. Temperature measurements can be
performed using I
where k is Boltzman’s constant and q is the absolute
value of the charge on electron. A four-measurement
procedure is adopted to improve accuracy by precisely
measuring the ratio of I
1) Current I
2) For the same current, the voltage across the diode
3) Repeat steps 1 and 2 with I
Since only four integer numbers are accessible from the
ADC conversions at a certain voltage reference, the previ-
ous equation can be represented in the following manner:
where N
ment results in integer format and V
voltage used in the ADC measurements.
The four-current method is used to account for the
diode series resistance and trace resistance. The four
currents are defined as follows; I
the currents are selected so (M
effect of the series resistance is eliminated from the
temperature measurements. For the currents I
and I
M
and I
current method, two measurements per current are
UPIOs, RTC, Voltage Monitors, and Temp Sensor
2
resistor R, and the voltage across the diode is mea-
sured as V
and R is measured as V
I
2
= 2. This results in the currents I
16-Bit Data-Acquisition System with ADC, DAC,
2
4
is typically 60µA (see Table 21).
= 60µA, the factors are selected as M
= M
T
V1
MEAS
T
, N
2
MEAS
1
I
2
is driven through the diode and the series
BE1
V2
= 120µA (typ). As in the case of the two-
, N
=
.
1
=
______________________________________________________________________________________
and I
nk
VBE1
q N
q V
(
(
ln
1
nk
BE
, and N
2
VBE
and I
⎛
⎜
⎝
.
N
N
1
2
ln
V
V
.
2
−
⎛
⎜
⎝
2
1
2
I
−
V
I
−
−
2
1
2
:
BE
N
1
. I
N
N
⎞
⎟
⎠
VBE2
VBE
1
Four-Current Method
VBE
VBE
Two-Current Method
- 1)I
1
1
, I
)
is typically 4µA, and
2
REF
1
, M
1
2
)
1
are the measure-
3
⎞
⎟
⎠
= (M
1
is the reference
= M
×
I
1
V
1
, and M
2
REF
16
2
1
and I
1
I
- 1)I
1
= 16 and
1
= 64µA
= 4µA
2
2
2
, the
I
2
are
BE
. If
used to improve accuracy by precisely measuring the
values of the currents.
1) Current I
2) For the same current, the voltage across the diode and
3) Repeat steps 1 and 2 with I
The measured temperature is defined as follows:
where V
For an external temperature sensor, either the two-cur-
rent or four-current method can be used. Connect an
external diode (such as 2N3904 or 2N3906) between
pins AIN1 and AGND (or AIN2 and AGND). Connect a
sense resistor R between AIN1 and AIN2. Maximize R
so the IR drop plus V
I
or (AV
temperature sensor can be used for the external tem-
perature sensor, by routing the currents to AIN1 (or
AIN2) (see Table 20).
For the two-current method, if the external diode’s
series resistance (R
measurement can be corrected as shown below:
To account for various error sources during the temper-
ature measurement, the internal temperature sensor is
calibrated at the factory. The calibrated temperature
equation is:
MAX
T
T
MEAS
ACTUAL
resistor R, and the voltage is measured across the
diode using the ADC as N
the series resistor is measured by the ADC as N
)+V
DD
=
REF
BE
=
q N
- 400mV). The same procedure as the internal
M
T
M
(
] is the smaller of the ADC reference voltage
MEAS
1
1
2
is the reference voltage used and:
VBE
is driven through the diode and the series
=
⎛
⎜
⎝
−
3
N
⎛
⎜
⎜
⎜
⎜
⎝
N
q N
−
V
V
(
N
3
1
S
V
VBE
−
−
Temperature-Sensor Calibration
2
) is known, then the temperature
nkIn
N
N
nkIn
−
N
VBE
VBE
External Temperature Sensor
BE
1
VBE
)
⎛
⎜
⎝
−
N
⎛
⎜
⎝
N
1
3
V
M
of the p-n junction [(R x
2
M
V
q N
VBE1
2
)
1
⎞
⎟
⎠
(
2
−
2
1
−
−
⎛
⎜
⎝
, I
q N
⎞
⎟
⎠
N
N
VBE
N
N
(
VBE
VBE
3
V
V
.
V
, and I
4
2
1
4
1
2
−
−
−
⎞
⎟
⎠
N
−
N
N
VBE
N
VBE
VBE
VBE
4
1
.
)
2
4
×
2
⎞
⎟
⎠
V
2
)
REF
16
×
V
V1
×
2
REF
16
R
.
R
S
⎞
⎟
⎟
⎟
⎟
⎠
31