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LMX2305 Datasheet

PLLatinumTM 550 MHz Frequency Synthesizer for RF Personal Communications

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PRELIMINARY
August 1996
LMX2305
PLLatinumTM 550 MHz Frequency Synthesizer
for RF Personal Communications
General Description
The LMX2305 is a high performance frequency synthesizer
with an integrated prescaler designed for RF operation up to
550 MHz It is fabricated using National’s ABiC IV BiCMOS
process
The LMX2305 contains a dual modulus prescaler which can
select either a 64 65 or a 128 129 divide ratio at input fre-
quencies of up to 550 MHz LMX2305 which employs the
digital phase lock loop technique combined with a high
quality reference oscillator and a loop filter provides the
tuning voltage for the voltage controlled oscillator to gener-
ate a very stable low noise local oscillator signal
Serial data is transferred into the LMX2305 via a three line
MICROWIRETM interface (Data Enable Clock) Supply volt-
age can range from 2 65V to 5 5V The LMX2305 features
very low current consumption typically 4 0 mA at 2 75V
The LMX2305 is available in a TSSOP 20-pin surface mount
plastic package
Features
Y RF operation up to 550 MHz
Y 2 65V to 5 5V operation
Y Low current consumption
ICC e 4 0 mA (typ) at VCC e 2 75V
Y Dual modulus prescaler 64 65 or 128 129
Y Internal balanced low leakage charge pump
Y Small-outline plastic surface mount TSSOP
0 173 wide package
Applications
Y Analog Cellular telephone systems
(AMPS ETACS NMT)
Y Portable wireless communications
(PCS PCN cordless)
Y Wireless local area networks (WLANs)
Y Other wireless communication systems
Y Pagers
Block Diagram
TL W 12459 – 1
TRI-STATE is a registered trademark of National Semiconductor Corporation
MICROWIRETM and PLLatinumTM are trademarks of National Semiconductor Corporation
C1996 National Semiconductor Corporation TL W 12459
RRD-B30M126 Printed in U S A
http www national com


National Semiconductor Electronic Components Datasheet

LMX2305 Datasheet

PLLatinumTM 550 MHz Frequency Synthesizer for RF Personal Communications

No Preview Available !

Connection Diagram
LMX2305
Pin Descriptions
Pin No
1
Pin Name
OSCIN
IO
I
3
OSCOUT
O
4 VP
5 VCC
6 Do
O
7 GND
8 LD
O
10 fIN
11 CLOCK
I
I
13 DATA
14 LE
I
I
15 FC
16 BISW
17 fOUT
18 wp
19 PWDN
I
O
O
O
I
20
2 9 12
wr
NC
O
TL W 12459 – 2
20-Lead (0 173 Wide) Thin Shrink
Small Outline Package (TM)
Order Number LMX2305TM or LMX2305TMX
See NS Package Number MTC20
Description
Oscillator input A CMOS inverting gate input intended for connection to a crystal resonator for
operation as an oscillator The input has a VCC 2 input threshold and can be driven from an
external CMOS or TTL logic gate May also be from a reference oscillator
Oscillator output
Power supply for charge pump Must be t VCC
Power supply voltage input Input may range from 2 65V to 5 5V Bypass capacitors should be
placed as close as possible to this pin and be connected directly to the ground plane
Internal charge pump output For connection to a loop filter for driving the input of an external
VCO
Ground
Lock detect Output provided to indicate when the VCO frequency is in ‘‘lock’’ When the loop is
locked the pin’s output is HIGH with narrow low pulses
Prescaler input Small signal input from the VCO
High impedance CMOS Clock input Data is clocked in on the rising edge into the various
counters and registers
Binary serial data input Data entered MSB first LSB is control bit High impedance CMOS input
Load enable input (with internal pull-up resistor) When LE transitions HIGH data stored in the
shift registers is loaded into the appropriate latch (control bit dependent) Clock must be low
when LE toggles high or low See Serial Data Input Timing Diagram
Phase control select (with internal pull-up resistor) When FC is LOW the polarity of the phase
comparator and charge pump combination is reversed
Analog switch output When LE is HIGH the analog switch is ON routing the internal charge
pump output through BISW (as well as through Do)
Monitor pin of phase comparator input CMOS output
Output for external charge pump wp is an open drain N-channel transistor and requires a pull-up
resistor
Power Down (with internal pull-up resistor)
PWDN e HIGH for normal operation
PWDN e LOW for power saving
Power down function is gated by the return of the charge pump to a TRI-STATE condition
Output for external charge pump wr is a CMOS logic output
No connect
http www national com
2


Part Number LMX2305
Description PLLatinumTM 550 MHz Frequency Synthesizer for RF Personal Communications
Maker National Semiconductor
Total Page 14 Pages
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