LV2700V Datasheet, PDF (8/9 Pages) Sanyo Semicon Device – Spread Spectrum Communications IC

LV2700V
reducing upper harmonic, high band, and other noise in audio signals. The LV2700V is designed so that good quality
audio signals can be acquired by connecting an external filter between pins 23 and 24. The pin 24 output includes a
buffer amplifier, thus making it a low-impedance output so that this output does not influence the pin 25 loop filter.
5. Pin 7
The DC bias of the amplifier that is connected after the 150-kHz low-pass filter is set with an external resistor. Select
a value for this resistor so that V7 will be 1.2 volts when V_CC is 3 volts.
6. Lock detection
The LOCK DET pin (a CMOS-level output) goes high when PN code synchronization is detected. This output can be
used as a simple technique for determining whether or not a carrier is present.
7. The ANTDUMP pin (pin 5)
This pin outputs a DC level proportional to the RF input level. However, since this level is proportional to the input
dBm value, it is not appropriate for use as an S-meter signal. It indicates voltage changes that are only meaningful in
strong field reception conditions. It can be used to prevent saturation of the front end RF amplifier. However, the
voltage change is +0.5 volt. (The pin 5 voltage for low input levels will be about 1.2 V.)
8. Power supply voltage application
[TX mode]
Provide the power-supply voltage to all the power-supply pins TXV_CC, RFV_CC, RXV_CC, and V_DD. Power saving is
applied to the RF block bias internally.
[RX mode]
Provide the power-supply voltage to the RFV_CC, RXV_CC, and V_DD pin. TXV_CC must be left open.
9. When changing the RF frequency from 236 MHz
There are cases, for example due to considerations related to the SAW resonator characteristics, where it may be
desirable to construct a system using a frequency other than 236 MHz. A 236-MHz AM synchronization detection
output is used for PN code synchronization control. Since an RC circuit is used for the VCO output 90° phase shift
circuit for this AM synchronization detection, it may not be possible to acquire the stipulated phase difference if the
frequency is moved significantly far from 236 MHz. Assuming that a range of 45±5° is allowed, the corresponding
frequency range will be 200 to 280 MHz.
Characteristics
236-MHz VCO Control Characteristics
236-MHz VCO control characteristics
Vt (V)
No. 5651-8/9