8-Channel, 200 kSPS, 12-Bit ADC
with Sequencer in 20-Lead TSSOP
Data Sheet
Rev. D
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FEATURES
Fast throughput rate: 200 kSPS
Specified for AVDD of 2.7 V to 5.25 V
Low power
3.6 mW maximum at 200 kSPS with 3 V supply
7.5 mW maximum at 200 kSPS with 5 V supply
8 (single-ended) inputs with sequencer
Wide input bandwidth
70 dB minimum SINAD at 50 kHz input frequency
Flexible power/serial clock speed management
No pipeline delays
High speed serial interface SPI-, QSPI-, MICROWIRE-,
DSP-compatible
Shutdown mode: 0.5 μA maximum
20-lead TSSOP
Qualified for automotive applications
GENERAL DESCRIPTION
The AD7927 is a 12-bit, high speed, low power, 8-channel,
successive approximation ADC. The part operates from a
single 2.7 V to 5.25 V power supply and features throughput
rates up to 200 kSPS. The part contains a low noise, wide
bandwidth track-and-hold amplifier that can handle input
frequencies in excess of 8 MHz.
The conversion process and data acquisition are controlled using
CS and the serial clock signal, allowing the device to easily interface
with microprocessors or DSPs. The input signal is sampled on the
falling edge of CS and the conversion is also initiated at this
point. There are no pipeline delays associated with the part.
The AD7927 uses advanced design techniques to achieve
very low power dissipation at maximum throughput rates. At
maximum throughput rates, the AD7927 consumes 1.2 mA
maximum with 3 V supplies; with 5 V supplies, the current
consumption is 1.5 mA maximum.
Through the configuration of the control register, the analog
input range for the part can be selected as 0 V to REFIN or 0 V
to 2 × REFIN, with either straight binary or twos complement
output coding. The AD7927 features eight single-ended analog
inputs with a channel sequencer to allow a preprogrammed
selection of channels to be converted sequentially.
The conversion time for the AD7927 is determined by the
SCLK frequency, as this is also used as the master clock to
control the conversion. The conversion time may be as short
as 800 ns with a 20 MHz SCLK.
FUNCTIONAL BLOCK DIAGRAM
CONTROL LOGIC
AGND
SCLK
DOUT
DIN
CS
AD7927
VDRIVE
AVDD
REFIN
VIN0
VIN7
INPUT
MUX
03
08
8-
0
01
SEQUENCER
12-BIT
SUCCESSIVE
APPROXIMATION
ADC
T/H
Figure 1.
PRODUCT HIGHLIGHTS
1.
High Throughput with Low Power Consumption.
The AD7927 offers up to 200 kSPS throughput rates. At the
maximum throughput rate with 3 V supplies, the AD7927
dissipates 3.6 mW of power maximum.
2.
Eight Single-Ended Inputs with a Channel Sequencer.
A consecutive sequence of channels can be selected on
which the ADC cycles and converts.
3.
Single-Supply Operation with VDRIVE Function.
The AD7927 operates from a single 2.7 V to 5.25 V supply.
The VDRIVE function allows the serial interface to connect
directly to either 3 V or 5 V processor systems independent
of AVDD.
4.
Flexible Power/Serial Clock Speed Management.
The conversion rate is determined by the serial clock,
allowing the conversion time to be reduced through the
serial clock speed increase. The part also features various
shutdown modes to maximize power efficiency at lower
throughput rates. Current consumption is 0.5 μA maxi-
mum when in full shutdown.
5.
No Pipeline Delay.
The part features a standard successive approximation ADC
with a CS input pin, which allows for accurate control of
each sampling instant.