11-26
RF2513
Rev B8 010509
11
Pin
Function
Description
Interface Schematic
14
MOD CTRL
This pin is used to select the prescaler modulus. A logic “high” selects
64 or 128 for the prescaler divisor. A logic “low” selects 65 or 129 for
the prescaler divisor.
15
DIV CTRL
This pin is used to select the desired prescaler divisor. A logic “high”
selects the 64/65 divisor. A logic low selects the 128/129 divisor.
16
MOD IN
FM analog or digital modulation can be imparted to the VCO through
this pin. The VCO varies in accordance to the voltage level presented
to this pin. To set the deviation to a desired level, a voltage divider refer-
enced to Vcc is the recommended. Because the modulation varactors
are part of the resonator tank, the deviation is slightly dependent upon
the components used in the external tank.
See pin 18.
17
VCC2
This pin is used to is supply DC bias to the VCO, prescaler, and PLL.
18
RESNTR-
The RESNTR pins are used to supply DC voltage to the VCO, as well
as to tune the center frequency of the VCO. Equal value inductors
should be connected to this pin and pin 20.
19
NC
Not internally connected.
20
RESNTR+
See pin 18.
See pin 18.
21
GND3
GND is the ground shared on chip by the VCO, prescaler, and PLL
electronics. Keep traces physically short and connect immediately to
ground plane for best performance.
22
VCO TUNE
Loop filter input to VCO.
23
LOOP FLT
OUT
Output of the charge pump. An RC network from this pin to ground is
used to establish the PLL bandwidth.
24
OSC SEL
A logic high (OSC SEL>2.0V) applied to this pin powers on reference
oscillator 2 and powers down reference oscillator 1. A logic low (OSC
SEL<1.0V) applied to this pin powers on reference oscillator 1 and
powers down reference oscillator 2.
ESD
This diode structure is used to provide electrostatic discharge protec-
tion to 3kV using the Human body model. The following pins are pro-
tected: 1-3, 9, 10,12-15, 17, 21-23.
MOD CTL
DIV CTL
RESNTR-
RESNTR+
4k
Ω
MOD IN
RESNTR-
RESNTR+
4k
Ω
VCO TUNE
LOOP FLT
V
CC
V
CC
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