HA11560 Datasheet, PDF (6/10 Pages) Hitachi Semiconductor – VCR/VDP RF Modulator

HA11560FP/T
RF Oscillator/Channel Switch
A new type RF oscillator is employed to reduce RF
harmonics to a level that is dramatically lower than
previous available Hitachi products.
Note that using a capacitor lower than 0.22 µF at
pin 3 causes an increase in sync pulse sag.
The input resistance at pin 11, which is the
oscillator input pin, is 3 kΩ. Pins 9 and 10 are
oscillator output pins, and are NPN transistor
emitter-follower types.
The oscillator frequency is selectable by switching
the pin 7 channel switch between SAW resonator
low channel and high channel. When the channel
switch is open, oscillation output is performed
from pin 9, while grounding the switch causes
output from pin 10. The switching voltage of the
channel switch is approximately 2.1 V. When the
channel switch is grounded, a current of 30 µA
flows through pin 7, which is sufficient to drive an
electronic switch.
Antenna Switch
RF oscillator on/off operation.
Opening the switch at pin 13 stops oscillation of
the RF oscillator and the antenna switch drive
output at pin 14 becomes 0 V. The audio system is
operating in this state, which acts to suppress
generation of popping noise in the audio as the
antenna switches between on and off.
When pin 13 is connected to V_CC by a closed
switch, the RF oscillator is operational and the
antenna switch drive output DC level at pin 14 is
high.
Pin 13 should be connected to V_CC when the
antenna switch is not used. A maximum current of
30 mA can be obtained from the antenna switch
driver.
Be sure to connect 10 kΩ for R3 at pin 13 when
the antenna switch is being used. R2 is used as
protective resistance when the antenna switch
power supply is switched on before the chip power
supply.
The antenna switch links the drive circuit that
switches the RF switch on and off with the chip’s
SAW resonator
11
10
9
3k
7
3₊
Channel
switch
C2
RF oscillator ^{0.22 µ}
Figure 3 RF Oscillator Interface Circuit
6
RF switch
14
R2 10 k
13
80 k
RF oscillator
Antenna switch
driver
V_CC
60 k
60 k
Figure 4 Antenna Switch Interface Circuit