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SP8537
Micropower Sampling 10-Bit A/D Converter
s s s s s s s s Low Cost 10-Bit Serial Sampling ADC 8-Pin NSOIC Plastic Package Low Power @ 250µA including Automatic Shutdown: 1nA(typ) Programmable Input Configuration: Full differential or 2 channel single-ended Single Supply 3.0V to 5.5V operation Half Duplex Digital Serial Interface Sample Rate: 33.9µS
DESCRIPTION The SP8537 is a very low power 10-Bit data acquisition chip. TheSP8537 typically draws 250µA of supply current when sampling at 29.5 kHz. Supply current drops linearly as the sample rate is reduced. The ADC automatically powers down when not performing conversions, drawing only leakage current. The SP8537 is available in 8-Pin NSOIC packages, specified over Commercial, Industrial and Extended temperature ranges. The SP8537 is best suited for Battery-Operated Systems, Portable Data Acquisition Instrumentation, Battery Monitoring, and Remote Sensing applications. The serial port allows efficient data transfer to a wide range of microprocessors and microcontrollers over 3 or 4 wires.
GND VCC
REFL
REFH
Internal VCC
10
REFL
DAC
REFH
Csample P
CH0 PARALLEL TO SERIAL SHIFT REGISTER
MUX
CH1
COMPARATOR
SAR
Dout
Csample N
DIN
INPUT DATA REG
CS CLK
TIMING & CONTROL LOGIC
SP8537 Block Diagram
SP8537DS/03 SP8537 Micropower Sampling 10–Bit Voltage A/D Converter © Copyright 2000 Sipex Corporation
1
ABSOLUTE MAXIMUM RATINGS
These are stress ratings only and functional operation of the device at these ratings or any other above those indicated in the operation sections of the specifications below is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability. (TA=+25˚C unless otherwise noted) ..................................................... VCC to GND ................................................................................. 7.0V Vin to GND .............................................................. -0.3 to VCC +0.3V Digital input to GND ................................................ -0.3 to VCC +0.3V Digital output to GND .............................................. -0.3 to VCC +0.3V Operating Temperature Range Commercial (J, K Version) ........................................... 0˚C to 70˚C Industrial (A, B Version) .......................................... -40˚C to +85˚C Lead Temperature (Solder 10Sec) ............................................ +300˚C Storage Temperature .................................................. -65˚C to +150˚C Power Dissipation to 70˚C ........................................................ 500mW
SPECIFICATIONS
Unless otherwise noted the following specifications apply for VCC=5V or 3.3V with limits applicable for Tmin to Tmax. Typical applies for Ta=25˚C.
PARAMETERS DC ACCURACY Resolution Integral Linearity K,B Differential Linearity Error K,B Gain Error K,B Offset Error K,B ANALOG INPUT Input Signal FS Range Input Impedance On Channel Off Channel Input Bias Current Analog Input Range MULTIPLEXER Crosstalk (fD = Nyquist) Feedthrough (fD = Nyquist) CONVERSION SPEED Sample Time Conversion Time Complete Cycle Clock Period Clock High Time Clock Low Time
VCC=5.0V VCC=3.3V MIN. TYP. MAX. MIN. TYP. MAX. 10 +0.5 +1.0 +0.6 +2.0 +0.2 +2.0 +0.6 +2.0 0 VCC 0 10 +0.5 +1.0 +0.6 +2.0 +0.2 +2.0 +0.6 +3.0 VCC 20 100 3 100 .001 1 VCC+.05 -90 -90
UNITS Bits LSB LSB LSB LSB
CONDITIONS
20 100 3 100 .001 1 -.05 VCC+.05 -.05 -90 -90
pF MΩ pF MΩ µA Volts dB dB
In Parallel with 100MΩ In Parallel with 100MΩ
Off to On Channel Off to On Channel fD= Disturbance See Timing Diagrams See Timing Diagrams See Timing Diagrams See Timing Diagrams See Timing Diagrams See Timing Diagrams
1.5 10 29.5 2.25 1.0 1.0 10 4.5 4.5
1.5 10 6.66
clock cycles clock cycles kHz µS µS µS
SP8537DS/03
SP8537 Micropower Sampling 10–Bit Voltage A/D Converter
© Copyright 2000 Sipex Corporation
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SPECIFICATIONS (cont.)
Unless otherwise noted the following specifications apply for VCC=5V or 3.3V with limits applicable for Tmin to Tmax. Typical applies for Ta=25˚C.
PARAMETERS DIGITAL INPUTS Input Low Voltage, VIL Input High Voltage, VIH Input Current IIN Input Capacitance DIGITAL OUTPUTS Data Format Data Coding VOH VOL AC ACCURACY Spurious free Dynamic Range (SFDR)
VCC=5.0V VCC=3.3V MIN. TYP. MAX. MIN. TYP. MAX. UNITS 0.8 2.0 +2.0 3.0 3.0 2.0 +2.0 0.8 Volts Volts µA pF
CONDITIONS VDD=5V +5% VDD=5V +5%
4.0 0.4
2.0 0.4
Volts Volts
See Timing Diagram VDD=5V ±5%, IOH=-0.4mA VDD=5V ±5%, IOH=+1.6mA
71
72
dB
For all FFT’s (Full Differential Mode) If VCC = 5V fsample = 25kHz fin = 12kHz
Total Harmonic Distortion (THD) Signal to Noise & Distortion (SINAD) Signal to Noise (SNR) SAMPLING DYNAMICS Acquisition Time to 0.05% -3dB Small Signal BW Aperture Delay Aperture Jitter Common-Mode Rejection Ratio
-67 59 60
-68 59 60
dB dB dB If VCC = 3.3V fsample = 6.66kHz fin = 2.8kHz
2 5 20 150 80
3.38
2 4 30 150 80
6.00
µs MHz nS pS dB
70
70
fCM = 12.5kHz @ 5 volts 2.8kHz @ 3..