Current-to-Digital ADC. ADAS1135 Datasheet
Current-to-Digital ADC Module
256-channel, current-to-digital converter module
Up to 24-bit resolution
Variable integration time
Fastest integration time: 22.6 kSPS maximum
(44.2 μs minimum) at 20-bit resolution
Low power dissipation: 2.3 mW per channel at any
±0.050% of reading, ±1.0 ppm of FSR: all channels active
Very low noise
No dead time, no loss of charge, 100% charge collection
User adjustable full-scale range
On-board temperature sensor and reference buffer
15 mm × 15 mm, CSP_BGA package
Simple printed circuit board (PCB) design
Integrated capacitors for supply and reference decoupling
0.80 mm pitch BGA allows low cost PCB technology
Reference design with reference layout
FPGA Verilog code
Medical, industrial, and security CT scanner data acquisition
Dosimetry and radiation therapy systems
Optical fiber power monitoring
X-ray detection systems
High channel count data acquisition systems (current or
The ADAS1135 is a 256-channel, current-to-digital, analog-to-
digital converter (ADC) module. It contains 256 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 of up to 24 bits. The signal chain
and sampling architecture of the ADAS1135 is designed to
guarantee that all channels are simultaneously sampled, and
that no charge is lost throughout the sampling process.
All converted channel results are output on a dual, low voltage
differential signaling (LVDS), self clocked serial interface,
which reduces external hardware.
An SPI-compatible serial interface allows configuration of the
ADC using the SDI_x input. The SDO_x output allows the
user to daisy-chain several ADCs on a single, 4-wire bus. The
ADAS1135 uses the separate supply, IOVDD, to reduce digital
noise effect on the conversions.
The ADAS1135 is in a 15 mm × 15 mm, CSP_BGA package.
For more information on the ADAS1135, contact Analog
Devices, Inc., at: firstname.lastname@example.org.
FUNCTIONAL BLOCK DIAGRAM
1.8V 2.5V 3.3V
TO NEXT SDI
TO ALL ADCs
VDD1 VDD2 VDD3
OF OTHER ADCs
REF 2.048V SDI_x
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