8-Bit CMOS Digital Temperature Sensor with
ADC Output
FEATURES
8-Bit ADC with 1ms Conversion Times
o
o
On-Chip Temperature Sensor: –20 C to +108 C
Over-temperature Indicator
Automatic Power-Down at the End of a
Conversion
Wide Operating Supply Range: 2.7 V to 5.5 V
Parallel or Serial Digital Output for SoC
Integration
APPLICATIONS
Personal Computers
Ambient Temperature Monitoring
Battery-Charging Applications
Industrial Process Control
Automotive
FUNCTIONAL BLOCK DIAGRAM
GENERAL DESCRIPTION
This analog block has an 8-bit single channel ADC
with an on-chip temperature sensor that can
operate from a single 2.7 V to 5.5 V power supply.
The ADC is a 1ms successive approximation
converter. Within the block, a temperature sensor,
a clock oscillator and a sample-and-hold are
present. When a conversion is initiated, the
resulting ADC code at the end of the conversion
gives a measurement of the chip or ambient
o
o
temperature (±3 C @ 25 C un-calibrated or ±
o
1 C calibrated). On-chip register can be
programmed to provide an over-temperature
indicator, which becomes active when a
programmed limit is exceeded.
SPECIFICATIONS (VDD = 2.8 V to 5.5 V, GND = 0 V, unless otherwise noted.)
Parameter
Value
Unit
DC ACCURACY
Resolution
Differential Nonlinearity
Relative Accuracy
Gain Error
Offset Error
8
±1
±1
±5
±5
Bits
LSB (typical)
LSB (typical)
LSB (typical)
LSB (typical)
TEMPERATURE SENSOR
Error @ 25C
Temperature Resolution
±3 or ±1 (calibrated)
0.5
o
CONVERTION RATE
Convertion Time
1
ms (typical)
DIGITAL OUTPUTS
Output Low Voltage, VOL
Output High Voltage, VOH
GND ± 0.1
VDD ± 0.1
V
V
POWER REQUIREMENTS
VDD
IDD
IDD power down
2.8 - 5.5
300
<1
V
uA (typical)
uA
C (typical)
C/LSB (typical)
o
TEMPERATURE MEASUREMENT
The typical transfer characteristic of the temperature sensor is shown below. The results of the 8-bit conversion
o
o
can be converter to degree Celsius by using 0.5 C/LSB and offset with -20 C. Ideal temperature versus ADC
output characteristics:
Temp (C)
o
108 C
o
-20 C
0dec
255dec
ADC Output
TYPICAL MEASURED ERROR
Below is a typical measured silicon INL error of the ADC and temperature measurement:
8-bit Temperature Output INL
2
1
INL (LSB)
0
-1
-2
0
51
102
153
204
Code
TIMING DIAGRAM OF THE DIGITAL OUTPUT
Sample1
Sample2
Temperature
Clk(internal)
ADC out[7:0]
Data1
Data2
255
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