KDC5612EVAL Intersil, KDC5612EVAL Datasheet - Page 15

• 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

The calibration sequence is initiated on the rising edge of
RESETN, as shown in Figure 23. The over-range output
(OR) is set high once RESETN is pulled low, and remains in
that state until calibration is complete. The OR output returns
to normal operation at that time, so it is important that the
analog input be within the converter’s full-scale range to
observe the transition. If the input is in an over-range
condition the OR pin will stay high, and it will not be possible
to detect the end of the calibration cycle.
While RESETN is low, the output clock
(CLKOUTP/CLKOUTN) is set low. Normal operation of the
output clock resumes at the next input clock edge
(CLKP/CLKN) after RESETN is deasserted. At 250MSPS
the nominal calibration time is 200ms, while the maximum
calibration time is 550ms.
CLKOUTP
User-Initiated Reset
Recalibration of the ADC can be initiated at any time by
driving the RESETN pin low for a minimum of one clock
cycle. An open-drain driver with a drive strength of less than
0.5mA is recommended, RESETN has an internal high
impedance pull-up to OVDD. As is the case during power-on
reset, the SDO, RESETN and DNC pins must be in the
proper state for the calibration to successfully execute.
The performance of the KAD5612P changes with variations
in temperature, supply voltage or sample rate. The extent of
these changes may necessitate recalibration, depending on
system performance requirements. Best performance will be
achieved by recalibrating the ADC under the environmental
conditions at which it will operate.
A supply voltage variation of less than 100mV will generally
result in an SNR change of less than 0.5dBFS and SFDR
change of less than 3dBc.
In situations where the sample rate is not constant, best
results will be obtained if the device is calibrated at the
highest sample rate. Reducing the sample rate by less than
75MSPS will typically result in an SNR change of less than
0.5dBFS and an SFDR change of less than 3dBc.
RESETN
CLKN
CLKP
ORP
FIGURE 23. CALIBRATION TIMING
CALIBRATION
BEGINS
15
CALIBRATION
CALIBRATION
COMPLETE
TIME
KAD5612P
Figures 24 and 25 show the effect of temperature on SNR
and SFDR performance with calibration performed at -40°C,
+25°C, and +85°C. Each plot shows the variation of
SNR/SFDR across temperature after a single calibration at
-40°C, +25°C and +85°C. Best performance is typically
achieved by a user-initiated calibration at the operating
conditions, as stated earlier. However, it can be seen that
performance drift with temperature is not a very strong
function of the temperature at which the calibration is
performed. Full-rated performance will be achieved after
power-up calibration regardless of the operating conditions.
Analog Input
Each ADC core contains a fully differential input
(AINP/AINN, BINP/BINN) to the sample and hold amplifier
(SHA). The ideal full-scale input voltage is 1.45V, centered at
the VCM voltage of 0.535V as shown in Figure 26.
Best performance is obtained when the analog inputs are
driven differentially. The common-mode output voltage,
VCM, should be used to properly bias the inputs as shown in
Figures 27 through 29.
FIGURE 25. SFDR PERFORMANCE vs TEMPERATURE
FIGURE 24. SNR PERFORMANCE vs TEMPERATURE
-10
-15
15
10
-1
-2
-3
-4
-5
3
2
1
0
5
0
-40
-40
-15
-15
CAL DONE AT
-40°C
CAL DONE AT
CAL DONE AT
CAL DONE AT
TEMPERATURE (°C)
TEMPERATURE (°C)
-40°C
10
+85°C
10
+85°C
35
35
CAL DONE AT
CAL DONE AT
+25°C
+25°C
60
60
September 9, 2009
FN6803.2
85
85