5

LTC1340

IN (Pin 5): Signal Input. The internal amplifier amplifies

the signal input at this pin typically by 2.3 to the OUT pin.

sal or unusual behavior, allowing a direct connection to the

output of virtually any phase detector or loop filter pow-

AGND (Pin 6): Signal Ground. Connect AGND to the

ground plane in close proximity to the VCO ground. There

is an internal parasitic resistance of 50

Ω between AGND

and PGND.

OUT (Pin 7): Driver Output. OUT is the output of the

directly. The OUT pin requires an external capacitor

(

≥ 220pF) to AGND to ensure stability. OUT typically sinks

or sources 20

µA.

filter capacitor from CP to PGND.

CP (Pin 1): Charge Pump Output. This is the output of the

internal charge pump. The voltage at CP is nominally twice

a 0.1

µF bypass capacitor to PGND.

the LTC1340 operates normally. If SHDN is pulled low

(< 0.5V), the LTC1340 enters shutdown mode and the

supply current drops to less than 1

µA typically. In shut-

down, the charge pump output voltage collapses and the

OUT pin enters a high impedance state. If SHDN returns

high, the charge pump output requires 1.2ms typically to

resume full voltage.

PGND (Pin 4): Power Ground. This is the charge pump

ground. Connect PGND to the system power supply

return.

4.0

3.8

3.6

3.4

3.2

3.0

1340 G16

TEMPERATURE (

°C)

–50

0

–25

25

50

75

100

125

Charge Pump Frequency vs

Temperature

Small-Signal Response

1340 G18

Large-Signal Response

1340 G17

0V