AD9627-125EBZ Analog Devices Inc, AD9627-125EBZ Datasheet - Page 35

• Manufacturer Part Number: AD9627-125EBZ
• Description: 12Bit 125 Msps Dual 1.8V PB Free ADC
• Manufacturer: Analog Devices Inc

Specifications of AD9627-125EBZ

• Number Of Adc's: 2
• Number Of Bits: 12
• Sampling Rate (per Second): 125M
• Data Interface: Serial
• Inputs Per Adc: 1 Differential
• Input Range: 2 Vpp
• Power (typ) @ Conditions: 900mW @ 125MSPS
• Voltage Supply Source: Analog and Digital
• Operating Temperature: -40°C ~ 85°C
• Utilized Ic / Part: AD9627
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Increment Gain (IG) and Decrement Gain (DG)
The increment gain and decrement gain indicators are intended
to be used together to provide information to enable external
gain control. The decrement gain indicator works in conjunction
with the coarse upper threshold bits, asserting when the input
magnitude is greater than the 3-bit value in the coarse upper
threshold register (Address 0x105). The increment gain indicator,
similarly, corresponds to the fine lower threshold bits, except
that it is asserted only if the input magnitude is less than the
value programmed in the fine lower threshold register after the
dwell time elapses. The dwell time is set by the 16-bit dwell time
value located at Address 0x10A and Address 0x10B and is set in
units of ADC input clock cycles ranging from 1 to 65,535. The
fine lower threshold register is a 13-bit register that is compared
IG
C_UT OR F_UT*
F_LT
DG
*C_UT AND F_UT DIFFER ONLY IN ACCURACY AND LATENCY.
NOTE: OUTPUTS FOLLOW THE INSTANTANEOUS SIGNAL LEVEL AND NOT THE ENVELOPE BUT ARE GUARANTEED ACTIVE FOR A MINIMUM OF 2 ADC CLOCK CYCLES.
Figure 67. Threshold Settings for C_UT, F_UT, IG, DG, and F_LT
RISE ABOVE F_LT
TIMER RESET BY
Rev. B | Page 35 of 76
DWELL TIME
with the magnitude at the output of the ADC. This comparison
is subject to the ADC clock latency but allows a finer, more
accurate comparison. The fine upper threshold magnitude is
defined by the following equation:
The decrement gain output works from the ADC fast detect
output pins, providing a fast indication of potential overrange
conditions. The increment gain uses the comparison at the
output of the ADC, requiring the input magnitude to remain
below an accurate, programmable level for a predefined period
before signaling external circuitry to increase the gain.
The operation of the increment gain output and the decrement
gain output is shown in Figure 67.
dBFS = 20 log(Threshold Magnitude/2
UPPER THRESHOLD (COARSE OR FINE)
DWELL TIME
FINE LOWER THRESHOLD
TIMER COMPLETES BEFORE
SIGNAL RISES ABOVE F_LT
13
)
AD9627