lmx2337 National Semiconductor Corporation, lmx2337 Datasheet - Page 11

• Manufacturer Part Number: lmx2337
• Description: Pllatinum? Dual Frequency Synthesizer For Rf Personal Communications
• Manufacturer: National Semiconductor Corporation

Functional Description
(Continued)
Note 9: When the F
LD output is disabled it is actively pulled to a low logic state.
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Note 10: Lock detect output provided to indicate when the VCO frequency is in “lock”. When the loop is locked and a lock detect mode is selected, the pins output
is HIGH, with narrow pulses LOW. In the RF1/RF2 lock detect mode a locked condition is indicated when RF2 and RF1 are both locked.
Note 11: The Fastlock mode utilized the F
LD output pin to switch a second loop filter damping resistor to ground during fastlock operation. Activation of Fastlock
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occurs whenever the RF loop’s Icpo magnitude bit # 17 is selected HIGH (while the # 19 and # 20 mode bits are set for Fastlock).
Note 12: The Counter Reset mode bits R19 and R20 when activated reset all counters. Upon removal of the Reset bits the N counter resumes counting in “close”
alignment with the R counter. (The maximum error is one prescaler cycle). If the Reset bits are activated the R counter is also forced to Reset, allowing smooth ac-
quisition upon powering up.
SERIAL DATA INPUT TIMING
DS012332-8
Notes: Parenthesis data indicates programmable reference divider data.
Data shifted into register on clock rising edge.
Data is shifted in MSB first.
Test Conditions: The Serial Data Input Timing is tested using a symmetrical waveform around V
/2. The test waveform has an edge rate of 0.6V/ns with
CC
= 2.7V and 2.6V
= 5.5V.
amplitudes of 2.2V
@
V
@
V
CC
CC
PHASE COMPARATOR AND INTERNAL CHARGE PUMP CHARACTERISTICS
DS012332-9
Notes: Phase difference detection range: −2 to +2
The minimum width pump up and pump down current pulses occur at the D
pin when the loop is locked.
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