SP8538 Просмотр технического описания (PDF) - Signal Processing Technologies
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SP8538 Datasheet PDF : 12 Pages
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DESCRIPTION
The SP8538 is a 12 bit sampling ADC with a
programmable two channel multiplexer and
serial data interface. The ADC samples and
converts 12 bits of data in 40 µS with a 5V
supply voltage applied. The SP8538 will also
operate at a 3.3V supply at 170µS throughput.
The device automatically shuts down to a
+0.5 µA (MAX) level as soon as the chip is
deselected (CS=1). Serial data output is
available in an MSB first or LSB first format.
FEATURES
Two program bits, which are shifted into the
device prior to conversion, determine the input
configuration. In the single ended MUX
configuration the input signal will be applied to
either channel 0 or channel 1 and will be ground
referenced. The maximum full scale range is
VCC. In the full differential mode, the signal
will be applied between channel 0 and channel
1. The signals applied at each input may both
be dynamic. This is in contrast with pseudo
differential devices which must have input low
held at a constant level during conversion. The
converter will provide significant common mode
rejection when used in full differential manner.
Both inputs must remain between ground and
VCC for proper conversion.
The device uses a capacitive DAC architecture
which provides the sampling behavior. This
results in full Nyquist performance at the
fastest throughput rate (25 KHz) the device is
capable of.
The power supply voltage is variable from 3.0V
to 5.5V which provides supply flexibility. At the
5.0V supply level, conversion plus sampling
time is 40µS and supply current is 250µA (1.25
mW). With a 3.3V supply the conversion plus
sampling time is 170µS and current is reduced
to 150µA (0.5 mW).
The device features automatic shutdown and
will shutdown to a +0.5 µA power level as CS
is brought high (de-selected). Power is
proportional to conversion duty cycle and
varies from 250 µA at 40µS (Duty cycle =
100%) to 6.25µa at 1.6 ms (Duty cycle = 2.5%).
Examples:
Conversion rate
40 µS
80 µS
160 µS
ICC @ 5V
250 µA
125 µA
62.5 µA
Duty Cycle
100%
50%
25%
0DRESSING
Mux Addressing
SGL/DIFF ODD/SIGN
0
0
0
1
1
0
1
1
Channel #
0
1
VINH
VINL
VINH
VINL
VINH
VINH
GND
VINL
VINL
Comments
Full Differential Mode
Single Ended Mux Mode
ADC TRANSFER FUNCTION
INPUT VOLTAGE
(V -V )*
INH INL
0 LSB
1 LSB
2048 LSB
4094 LSB
4095 LSB
INPUT VOLTAGE
AT V /V = 5V
CC REF
0V
0.00122V
2.5000V
4.9976V
4.9988V
OUTPUT
CODE
000000000000
000000000001
100000000000
111111111110
111111111111
* See Mux Addressing Table for a definition of VINH - VINL.
SP8538DS/01
SP8538 Micropower Sampling 12-Bit A/D Converter
5
© Copyright 1999 Sipex Corporation
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