
MAX19706
10-Bit, 22Msps, Ultra-Low-Power
Analog Front-End
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15
PIN
NAME
FUNCTION
10
QAP
Channel-QA Positive Analog Input. For single-ended operation, connect signal source to QAP.
13–18, 21–24
D0–D9
Digital I/O. Outputs for receive ADC in Rx mode. Inputs for transmit DAC in Tx mode. D9 is the most
significant bit (MSB) and D0 is the least significant bit (LSB).
19
OGND
Output-Driver Ground
20
OVDD
Output-Driver Power Supply. Supply range from +1.8V to VDD. Bypass OVDD to OGND with a
combination of a 2.2F capacitor in parallel with a 0.1F capacitor.
25
SHDN
Active-Low Shutdown Input. Apply logic-low to place the MAX19706 in shutdown.
26
DOUT
Aux-ADC Digital Output
27
T/R
Transmit/Receive-Mode Select Input. T/R logic-low input sets the device in receive mode. A logic-
high input sets the device in transmit mode. If modes are set through SPI commands, the T/R input
must be pulled up to OVDD or pulled down to OGND.
28
DIN
3-Wire Serial-Interface Data Input. Data is latched on the rising edge of the SCLK.
29
SCLK
3-Wire Serial-Interface Clock Input
30
CS
3-Wire Serial-Interface Chip-Select Input. Logic-low enables the serial interface.
34
ADC2
Auxiliary ADC Analog Input
35
ADC1
Auxiliary ADC Analog Input
36
DAC3
Auxiliary DAC3 Analog Output
37
DAC2
Auxiliary DAC2 Analog Output
38
DAC1
Auxiliary DAC1 Analog Output (AFC DAC, VOUT = 1.1V During Power-Up)
40, 41
IDN, IDP
DAC Channel-ID Differential Voltage Output
44, 45
QDN, QDP
DAC Channel-QD Differential Voltage Output
46
REFIN
Reference Input. Connect to VDD for internal reference.
47
COM
Common-Mode Voltage I/O. Bypass COM to GND with a 0.33F capacitor.
48
REFN
Negative Reference I/O. Rx ADC conversion range is ±(VREFP - VREFN). Bypass REFN to GND with a
0.1F capacitor.
—
EP
Exposed Paddle. Exposed paddle is internally connected to GND. Connect EP to the GND plane.
Pin Description (continued)
MICROWIRE is a trademark of National Semiconductor Corp.
Detailed Description
The MAX19706 integrates a dual, 10-bit Rx ADC and a
dual, 10-bit Tx DAC while providing ultra-low power
and high dynamic performance at a 22Msps conver-
sion rate. The Rx ADC analog input amplifiers are fully
differential and accept 1.024VP-P full-scale signals. The
Tx DAC analog outputs are fully differential with
±400mV full-scale output, selectable common-mode
DC level, and adjustable I/Q offset trim.
The MAX19706 integrates three 12-bit auxiliary DAC
(aux-DAC) channels and a 10-bit, 333ksps auxiliary
ADC (aux-ADC) with 4:1 input multiplexer. The aux-DAC
channels feature 1s settling time for fast automatic
gain-control (AGC), variable-gain amplifier (VGA), and
automatic frequency-control (AFC) level setting. The
aux-ADC features data averaging to reduce processor
overhead and a selectable clock-divider to program the
conversion rate.
The MAX19706 includes a 3-wire serial interface to
control operating modes and power management. The
serial interface is SPI and MICROWIRE compatible.
The MAX19706 serial interface selects shutdown, idle,
standby, transmit (Tx), and receive (Rx) modes, as well
as controls aux-DAC and aux-ADC channels.
The Rx ADC and Tx DAC share a common digital I/O to
reduce the digital interface to a single, 10-bit parallel
multiplexed bus. The 10-bit digital bus operates on a
single +1.8V to +3.3V supply.