Adv a nc e Inform ation

FS8308

Page 15

April 2003

Single Voltage Operation

This IC requires two separate power supplies to operate. If only one voltage source is

available, ex. use battery to serve as power source, the user can apply the configuration as

shown in the following which is referred to as single voltage operation.

Since there is only one voltage source provided in the so-called single voltage configura-

tion, which is directly connected to V

V

that the lower V

output it drives. In order to balance the trade-off between the current consumption and

crystal buffer driving capability, V

ous R at fin=470MHz is plotted in the following figure. Note that although smaller resistor

R makes this IC consume more current, the reward is with wider power supply input

range. Typical value of R is recommended to be around 1.6K

Single Voltage Characteristic: Vdd1 vs. Vdd2 for Various R

VDD2

VDD1

R

POWER SUPPLY

1.5

2.0

2.5

3.0

3.5

4.0

0.8

0.9

1.0

1.1

1.2

1.3

1.4

1.5

Safe Operation Region

fin=470MHz, Pfin=-10dBm

xin=24MHz, N=4032, R=5

Vdd2 (V)

R=1.2K

R=1.6K

R=1.8K

R=2.0K