AD7914BRUZ Analog Devices Inc, AD7914BRUZ Datasheet - Page 15

• Manufacturer Part Number: AD7914BRUZ
• Description: 10-Bit 4,CH 1 Msps ADC I.C.
• Manufacturer: Analog Devices Inc

Specifications of AD7914BRUZ

• Number Of Bits: 10
• Sampling Rate (per Second): 1M
• Data Interface: DSP, MICROWIRE™, QSPI™, Serial, SPI™
• Number Of Converters: 1
• Power Dissipation (max): 13.5mW
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 16-TSSOP (0.173", 4.40mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: EVAL-AD79X4CBZ - BOARD EVALUATION FOR AD79X4CBZ
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

CS
CS
REV. 0
CS
CS
CS
Figure 2. SEQ1 Bit = 0, SEQ0 Bit = x Flowchart
Figure 3. SEQ1 Bit = 1, SEQ0 Bit = 1 Flowchart
DOUT: CONVERSION RESULT FROM PREVIOUSLY
SELECTED CHANNEL A1, A0
DIN: WRITE TO CONTROL REGISTER,
WRITE BIT = 1,
SELECT CODING, RANGE, AND POWER MODE.
SELECT A1, A0 FOR CONVERSION.
SEQ1 = 0, SEQ0 = x
DOUT: CONVERSION RESULT FROM CHANNEL 0
CONTINUOUSLY CONVERTS ON A CONSECUTIVE
SEQUENCE OF CHANNELS FROM CHANNEL 0 UP
TO AND INCLUDING THE PREVIOUSLY SELECTED
A1, A0 IN THE CONTROL REGISTER
CONTINUOUSLY CONVERTS ON THE SELECTED
SEQUENCE OF CHANNELS BUT WILL ALLOW
RANGE, CODING, AND SO FORTH, TO CHANGE IN
THE CONTROL REGISTER WITHOUT INTERRUPTING
THE SEQUENCE, PROVIDED SEQ1 = 1, SEQ0 = 0
DIN: WRITE TO CONTROL REGISTER,
WRITE BIT = 1,
SELECT CODING, RANGE, AND POWER MODE.
SELECT CHANNEL A1, A0 FOR CONVERSION.
SEQ1 = 0, SEQ0 = x
DIN: WRITE TO CONTROL REGISTER,
WRITE BIT = 1,
SELECT CODING, RANGE, AND POWER MODE.
SELECT CHANNEL A1, A0 FOR CONVERSION.
SEQ1 = 1, SEQ0 = 1
DUMMY CONVERSION
DUMMY CONVERSION
POWER ON
POWER ON
WRITE BIT = 1,
SEQ1 = 0, SEQ0 = x
WRITE BIT = 0
WRITE BIT = 1,
SEQ1 = 1,
SEQ0 = 0
–15–
CIRCUIT INFORMATION
The AD7904/AD7914/AD7924 are high speed, 4-channel, 8-bit,
10-bit, and 12-bit, single supply, A/D converters, respectively.
The parts can be operated from a 2.7 V to 5.25 V supply. When
operated from either a 5 V or 3 V supply, the AD7904/AD7914/
AD7924 are capable of throughput rates of 1 MSPS when pro-
vided with a 20 MHz clock.
The AD7904/AD7914/AD7924 provide the user with an on-chip
track/hold, A/D converter, and a serial interface housed in a
16-lead TSSOP package. The AD7904/AD7914/AD7924 each
have four single-ended input channels with a channel sequencer,
allowing the user to select a channel sequence through which the
ADC can cycle with each consecutive CS falling edge. The serial
clock input accesses data from the part, controls the transfer of
data written to the ADC, and provides the clock source for the
successive-approximation A/D converter. The analog input
range for the AD7904/AD7914/AD7924 is 0 V to REF
to 2 × REF
Register. For the 0 to 2 × REF
from a 4.75 V to 5.25 V supply.
The AD7904/AD7914/AD7924 provide flexible power
management options to allow the user to achieve the best power
performance for a given throughput rate. These options are
selected by programming the Power Management bits, PM1
and PM0, in the Control Register.
CONVERTER OPERATION
The AD7904/AD7914/AD7924 are 8-, 10-, and 12-bit successive
approximation analog-to-digital converters based around a
capacitive DAC, respectively. The AD7904/AD7914/AD7924
can convert analog input signals in the range 0 V to REF
to 2 × REF
the ADC. The ADC is comprised of Control Logic, SAR, and a
Capacitive DAC, which are used to add and subtract fixed amounts
of charge from the sampling capacitor to bring the comparator
back into a balanced condition. Figure 4 shows the ADC during
its acquisition phase. SW2 is closed and SW1 is in position A.
The comparator is held in a balanced condition and the sampling
capacitor acquires the signal on the selected V
V
V
IN
IN
AGND
0
3
IN
IN
, depending on the status of Bit 1 in the Control
. Figures 4 and 5 show simplified schematics of
Figure 4. ADC Acquisition Phase
SW1
A
AD7904/AD7914/AD7924
B
SW2
4k
IN
range, the part must be operated
COMPARATOR
IN
channel.
CAPACITIVE
DAC
CONTROL
LOGIC
IN
IN
or 0 V
or 0 V