ANALOG DEVICES ADAS1128 Service Manual

F

S/H

OR0

F

S/H

OR63

ADCL

+
–

AN0

AN63

F

S/H

OR64

F

S/H

OR127

ADCH

+
–

AN64

AN127

KGND

VT

DATA

PROCESSING

LVDS/CMOS
INTERFACE

TEMPERATURE

OR[0:127]

ADAS1128

BUFPL BUFNL

2.5V

3.3V

TO NEXT

SDI

SDI

SDO

BUFPH

BUFNH

REF

2.048V

SDI

FROM

PREVIOUS

SDO

SDI

REF

CONFIGURATION

SCK
CS

DOUTx
CLKx
SYNC

IOVDD

RESET

IOGND

TO ALL ADCs

2.5V

FROM DOUT

OF OTHER ADCs

FPGA

VIO

08045-001

128-Channel, 24-Bit Current-to-Digital ADC

FEATURES

128-channel, low level current-to-digital converter
Up to 24-bit resolution
Up to 19.7 kSPS (50.7 µs integration time)
Simultaneous sampling
Ultralow noise (down to 0.4 fC [2500e

−

])
User-adjustable full-scale range
INL: ±0.025% of reading ±0.75 ppm of FSR
Very low power dissipation: 4.5 mW/channel
LVDS self-clocked serial data interface
SPI configuration registers (daisy-chain)
On-board temperature sensor and reference buffer
10 mm × 10 mm, mini-BGA package
Low cost external components
Support tools

Evaluation board
Reference design with reference layout
FPGA Verilog code

APPLICATIONS

Medical, industrial, and security CT scanner data acquisition
Photodiode sensors
Dosimetry and radiation therapy systems
Optical fiber power monitoring
X-ray detection systems
High channel-count data acquisition systems (current or

voltage inputs)

ADAS1128

GENERAL DESCRIPTION

The ADAS1128 is a 128-channel, current-to-digital, analog-to­digital converter (ADC). It contains 128 low power, low noise,
low input current integrators, simultaneous sample-and-holds,
and two high speed, high resolution ADCs with configurable
sampling rate and resolutions up to 24 bits.

All converted channel results are output on a single LVDS self­clocked serial interface, which reduces external hardware.

An SPI-compatible serial interface allows configuration of the
ADC using the SDI input. The SDO output allows the user to
daisy-chain several ADCs on a single, 3-wire bus. The ADAS1128
uses the separate supply IOVDD to reduce digital noise effect
on the conversions.

The ADAS1128 is in a 10 mm × 10 mm, mini-BGA package.

FUNCTIONAL BLOCK DIAGRAM

Rev. SpC

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