Datasheet

AD9553
Rev. A | Page 10 of 44
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
NOTES
1. EXPOSED DIE PAD MUST BE CONNECTED TO GND.
PIN 1
INDICATOR
1Y4
2Y5
3A0
4A1
5A2
6A3
7REFA
8REFB/REFA
24 GND
23 OUT2
22
21 VDD
20 LOCKED
19 LDO
18 VDD
17 LDO
9
XTAL
10
XTAL
11
SEL RE
FB
12
13
OM1/SCLK
14
OM0/SDIO
15
RESET
16
FILTER
32
Y3
31
Y2
30
Y1
29
Y0
28
VDD
27
OUT
1
26
25
GND
TOP VIEW
(Not to Scale)
AD9553
OUT1
OUT2
OM2/CS
08565-002
Figure 2. Pin Configuration
Table 13. Pin Function Descriptions
Pin No. Mnemonic Type
1
Description
29, 30, 31,
32, 1, 2
Y0, Y1, Y2, Y3,
Y4, Y5
I Control Pins. These pins select one of 52 preset output frequency combinations for OUT1 and OUT2. Note
that when all six control pins are Logic 0, SPI programming is active.
3, 4, 5, 6 A0, A1, A2,
A3
I Control Pins. These pins select one of 15 preset input reference frequencies. Note that when all four control
pins are Logic 0, SPI programming is active.
7 REFA I Reference Clock Input. Connect this pin to a single-ended active clock input signal. Alternatively, this pin is
the noninverted part of a differential clock input signal.
8
REFB/
REFA
I Reference Clock Input. Connect this pin to a single-ended active clock input signal. Alternatively, this pin is
the inverted part of a differential clock input signal.
9, 10 XTAL I Crystal Resonator Input. Connect a crystal resonator across these pins. Alternatively, connect a single-ended
clock source (CMOS compatible) to either input pin (let the unused pin float). When using the preset
input/output frequencies via the Y5 to Y0 and A3 to A0 pins, the crystal must have a resonant frequency of
25 MHz with a specified load capacitance of 10 pF.
11 SEL REFB I Control Pin. This pin allows manual selection of REFA (Logic 0) or REFB (Logic 1) as the active reference
assuming that the desired reference signal is present. Note that this pin is nonfunctional when
Register 0x29[5] = 1.
12
OM2/
CS
I Digital Input. When the device is not in SPI mode, this pin is an output mode control pin (OM2) with an
internal 40 kΩ pull-up resistor. The OM2 pin, in conjunction with the OM0 and OM1 pins, allows the user to
select one of eight output configurations (see Table 21). In SPI mode, this pin is an active low chip select (
CS
)
with no internal pull-up resistor.
13 OM1/SCLK I Digital Input. When the device is not in SPI mode, this pin is an output mode control pin (OM1) with an
internal 40 kΩ pull-up resistor. The OM1 pin, in conjunction with the OM0 and OM2 pins, allows the user to
select one of eight output configurations (see Table 21). In SPI mode, this pin is the serial data clock (SCLK)
with no internal pull-up resistor.
14 OM0/SDIO I/O Digital Input/Output. When the device is not in SPI mode, this pin is an input only and functions as an
output mode control pin (OM0) with an internal 40 kΩ pull-up resistor. The OM0 pin, in conjunction with the
OM1 and OM2 pins, allows the user to select one of eight output configurations (see Table 21). In SPI mode,
this pin is the serial data input/output (SDIO) with no internal pull-up resistor.
15
RESET
I Reset Internal Logic. This is a digital input pin. This pin is active low with a 100 kΩ internal pull-up resistor
and resets the internal logic to default states (see the Automatic Power-On Reset section).
16 FILTER I/O Loop Filter Node for the PLL. Connect external loop filter components (see Figure 30) from this pin to Pin 17 (LDO).
17, 19 LDO P/O LDO Decoupling Pins. Connect a 0.47 μF decoupling capacitor from each of these pins to ground.
18, 21, 28 VDD P Power Supply Connection: 3.3 V Analog Supply.
20 LOCKED O Active High Locked Status Indicator for the PLL.
26, 22
OUT1
,
OUT2
O Complementary Square Wave Clocking Outputs.
27, 23 OUT1, OUT2 O Square Wave Clocking Outputs.
24, 25 GND P Ground.
Not
Applicable
EP Exposed Pad. The exposed die pad must be connected to GND.
1
I = input, I/O = input/output, O = output, P = power, and P/O = power/output.