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MAX19705
10-Bit, 7.5Msps, 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 MAX19705 in shutdown.
26
DOUT
Aux-ADC Digital Output
27
T/R
Transmit- or 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.
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
Analog Input for Auxiliary ADC
35
ADC1
Analog Input for Auxiliary ADC
36
DAC3
Analog Output for Auxiliary DAC3
37
DAC2
Analog Output for Auxiliary DAC2
38
DAC1
Analog Output for Auxiliary DAC1 (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.
—EPExposed Paddle. Exposed paddle is internally connected to GND. Connect EP to the GND plane.
Pin Description (continued)
SPI is a trademark of Motorola, Inc.
MICROWIRE is a trademark of National Semiconductor Corp.
Detailed Description
The MAX19705 integrates a dual 10-bit Rx ADC and a
dual 10-bit Tx DAC while providing ultra-low power and
high dynamic performance at 7.5Msps conversion 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 MAX19705 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 AGC, VGA,
and AFC level setting. The aux-ADC features data aver-
aging to reduce processor overhead and a selectable
clock-divider to program the conversion rate.
The MAX19705 includes a 3-wire serial interface to
control operating modes and power management. The
serial interface is SPI and MICROWIRE compatible.
The MAX19705 serial interface selects shutdown, idle,
standby, transmit (Tx), and receive (Rx) modes, as well
as controlling 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.