Datasheet

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SBAS255C − JUNE 2004 − REVISED APRIL 2009
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3
ELECTRICAL CHARACTERISTICS
At T
A
= +25°C, AVDD = +5V, DVDD = 3V, VREF = +4.096V, Range 5 (250pC), and continuous mode operation, unless otherwise noted.
Low-Power Mode: T
INT
= 400µs and CLK = 4MHz; High-Speed Mode: T
INT
= 320µs and CLK = 4.8MHz.
Low-Power Mode High-Speed Mode
PARAMETER TEST CONDITIONS MIN TYP MAX MIN TYP MAX UNITS
ANALOG INPUT RANGE
Range 0 10.2 12 13.8 ∗
(1)
∗ ∗ pC
Range 1 47.5 50 52.5 ∗ ∗ ∗ pC
Range 2 95 100 105 ∗ ∗ ∗ pC
Range 3 142.5 150 157.5 ∗ ∗ ∗ pC
Range 4 190 200 210 ∗ ∗ ∗ pC
Range 5 237.5 250 262.5 ∗ ∗ ∗ pC
Range 6 285 300 315 ∗ ∗ ∗ pC
Range 7 332.5 350 367.5 ∗ ∗ ∗ pC
Negative Full-Scale Range −0.4% of Positive Full-Scale Range ∗ pC
Input Current
(2)
750 ∗ µA
DYNAMIC CHARACTERISTICS
Data Rate 2.5 3.125 kSPS
Integration Time, T
INT
Continuous Mode 400 1,000,000 320 ∗ µS
Integration Time, T
INT
Non-continuous Mode, Range 1 to 7 50 ∗ µS
System Clock Input (CLK)
CLK_4X = 0 4 4.8 MHz
CLK_4X = 1 16 19.2 MHz
Data Clock (DCLK) 16 ∗ MHz
ACCURACY
Noise, Low-Level Input
(3)
C
SENSOR
(4)
= 50pF, Range 5 (250pC) 5.2 6.5 5.5 7
ppm of
FSR
(5)
, rms
Integral Linearity Error
(6)
±0.01% Reading ± 0.5ppm FSR, typ ∗
Integral Linearity Error
(6)
±0.025% Reading ± 1.0ppm FSR, max ∗
Resolution FORMAT = 1 20 ∗ Bits
Resolution
FORMAT = 0 16 ∗ Bits
Input Bias Current 0.1 10 ∗ ∗ pA
Range Error Match
(7)
All Ranges 0.1 0.5 ∗ ∗ % of FSR
Range Sensitivity to VREF V
REF
= 4.096 ± 0.1V 1:1 ∗
Offset Error ±400 ±1000 ∗ ∗ ppm of FSR
Offset Error Match
(7)
±100 ∗ ppm of FSR
DC Bias Voltage
(9)
Low-Level Input (< 1% FSR) ±0.05 ±2 ∗ ∗ mV
Power-Supply Rejection Ratio at dc ±25 ±200 ∗ ∗ ppm of FSR/V
Internal Test Signal 11 ∗ pC
Internal Test Accuracy ±10 ∗ %
PERFORMANCE OVER TEMPERATURE
Offset Drift ±0.5 ±3
(8)
∗ ∗
ppm of
FSR/°C
Offset Drift Stability ±0.2 ±1
(8)
∗ ∗
ppm of FSR/
minute
DC Bias Voltage Drift
(9)
3 ∗ µV/°C
Input Bias Current Drift T
A
= +25°C to +45°C 0.01 1
(8)
∗ ∗ pA/°C
Range Drift
(10)
25 ∗ ppm/°C
REFERENCE
Voltage 4.000 4.096 4.200 ∗ ∗ ∗ V
Input Current
(11)
Average Value 75 95 µA
(1)
∗ indicates that specification is the same as Low-Power Mode.
(2)
Exceeding maximum input current specification may damage device.
(3)
Input is less than 1% of full scale.
(4)
C
SENSOR
is the capacitance seen at the DDC114 inputs from wiring, photodiode, etc.
(5)
FSR is Full-Scale Range.
(6)
A best-fit line is used in measuring nonlinearity.
(7)
Matching between side A and side B of the same input.
(8)
Ensured by design, not production tested.
(9)
Voltage produced by the DDC114 at its input which is applied to the sensor.
(10)
Range drift does not include external reference drift.
(11)
Input reference current decreases with increasing T
INT
(see the Voltage Reference section, page 11).