KDC5612EVAL Intersil, KDC5612EVAL Datasheet - Page 14

• Manufacturer Part Number: KDC5612EVAL
• Description: DAUGHTER CARD FOR KAD5612
• Manufacturer: Intersil
• Series: FemtoCharge™r

Specifications of KDC5612EVAL

• Number Of Adc's: 2
• Number Of Bits: 12
• Sampling Rate (per Second): 250M
• Data Interface: Parallel
• Inputs Per Adc: 1 Differential
• Input Range: 1.47 Vpp
• Power (typ) @ Conditions: 429mW @ 250MSPS
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 85°C
• Utilized Ic / Part: KAD5612P-25, KMB001 Motherboard
• For Use With: KMB001LEVAL - MOTHERBOARD FOR LVDS ADC CARD
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Theory of Operation
Functional Description
The KAD5612P is based upon a 12-bit, 250MSPS A/D
converter core that utilizes a pipelined successive
approximation architecture (Figure 22). The input voltage is
captured by a Sample-Hold Amplifier (SHA) and converted
to a unit of charge. Proprietary charge-domain techniques
are used to successively compare the input to a series of
reference charges. Decisions made during the successive
approximation operations determine the digital code for each
input value. The converter pipeline requires six samples to
produce a result. Digital error correction is also applied,
resulting in a total latency of seven and one half clock cycles.
This is evident to the user as a latency between the start of a
conversion and the data being available on the digital
outputs.
The device contains two A/D converter cores with carefully
matched transfer characteristics. At start-up, each core
performs a self-calibration to minimize gain and offset errors.
The reset pin (RESETN) is initially set high at power-up and
will remain in that state until the calibration is complete. The
clock frequency should remain fixed during this time, and no
SPI communications should be attempted. Recalibration can
be initiated via the SPI port at any time after the initial
self-calibration.
INN
INP
1.25V
14
SHA
+
–
FIGURE 22. ADC CORE BLOCK DIAGRAM
2.5-BIT
FLASH
KAD5612P
1.5-BIT/STAGE
6-STAGE
Power-On Calibration
The ADC performs a self-calibration at start-up. An internal
power-on-reset (POR) circuit detects the supply voltage
ramps and initiates the calibration when the analog and
digital supply voltages are above a threshold. The following
conditions must be adhered to for the power-on calibration to
execute successfully:
• A frequency-stable conversion clock must be applied to
• DNC pins (especially pins 3, 4 and 18) must not be pulled
• SDO (pin 66) must be high
• RESETN (pin 25) must begin low
• SPI communications must not be attempted
A user-initiated reset can subsequently be invoked in the
event that the above conditions cannot be met at power-up.
The SDO pin requires an external 4.7kΩ pull-up to OVDD. If
the SDO pin is pulled low externally during power-up,
calibration will not be executed properly.
After the power supply has stabilized the internal POR
releases RESETN and an internal pull-up pulls it high, which
starts the calibration sequence. If a subsequent
user-initiated reset is required, the RESETN pin should be
connected to an open-drain driver with a drive strength of
less than 0.5mA.
LVDS/LVCMOS
GENERATION
CORRECTION
the CLKP/CLKN pins
up or down
OUTPUTS
DIGITAL
CLOCK
ERROR
1-BIT/STAGE
3-STAGE
FLASH
3-BIT
September 9, 2009
FN6803.2