PIN FUNCTION DESCRIPTIONS
Table 3. 48-Lead TQFP/EP
I The rising edge transfers the contents of the internal buffer memory to the I/O registers. This pin
must be set up and held around the SYNC_CLK output signal.
I Digital Power Supply Pins (1.8 V).
3, 33, 42,
4, 6, 13,
16, 18, 19,
25, 27, 29
I Digital Power Ground Pins.
I Analog Power Supply Pins (1.8 V).
5, 7, 14,
15, 17, 22,
I Analog Power Ground Pins.
I Complementary Reference Clock/Oscillator Input. When the REFCLK port is operated in single-
ended mode, REFCLK should be decoupled to AVDD with a 0.1 µF capacitor.
I Reference Clock/Oscillator Input. See Clock Input section for details on the OSCILLATOR/REFCLK
O Output of the Oscillator Section.
CLKMODESELECT I Control Pin for the Oscillator Section. When high, the oscillator section is enabled. When low, the
oscillator section is bypassed.
I This pin provides the connection for the external zero compensation network of the REFCLK
multiplier’s PLL loop filter. The network consists of a 1 kΩ resistor in series with a 0.1 µF capacitor
tied to AVDD.
O Complementary DAC Output. Should be biased through a resistor to AVDD, not AGND.
O DAC Output. Should be biased through a resistor to AVDD, not AGND.
I DAC Biasline Decoupling Pin.
I A resistor (3.92 kΩ nominal) connected from AGND to DAC_RSET establishes the reference current
for the DAC.
O Comparator Output.
I Compator Input.
I Compartor Complementary Input
I Input Pin Used as an External Power-Down Control (see Table 8 for details).
I Active High Hardware Reset Pin. Assertion of the RESET pin forces the AD9952 to the initial state,
as described in the I/O port register map.
I Asynchronous Active High Reset of the Serial Port Controller. When high, the current I/O
operation is immediately terminated, enabling a new I/O operation to commence once IOSYNC is
returned low. If unused, ground this pin; do not allow this pin to float.
O When operating the I/O port as a 3-wire serial port, this pin serves as the serial data output. When
operated as a 2-wire serial port, this pin is unused and can be left unconnected.
I This pin functions as an active low chip select that allows multiple devices to share the I/O bus.
I This pin functions as the serial data clock for I/O operations.
I/O When operating the I/O port as a 3-wire serial port, this pin serves as the serial data input only.
When operated as a 2-wire serial port, this pin is the bidirectional serial data pin.
I Digital Power Supply (for I/O Cells Only, 3.3 V).
I Input Signal Used to Synchronize Multiple AD9952s. This input is connected to the SYNC_CLK
output of a master AD9952.
O Clock Output Pin that Serves as a Synchronizer for External Hardware.
I Input Pin Used to Control the Direction of the Shaped On-Off Keying Function when
Programmed for Operation. OSK is synchronous to the SYNC_CLK pin. When OSK is not
programmed, this pin should be tied to DGND.
I The exposed paddle on the bottom of the package is a ground connection for the DAC and must
be attached to AGND in any board layout.
Rev. 0 | Page 9 of 28