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ML13175 View Datasheet(PDF) - LANSDALE Semiconductor Inc.

Part Name
Description
Manufacturer
ML13175
LANSDALE
LANSDALE Semiconductor Inc. LANSDALE
ML13175 Datasheet PDF : 16 Pages
1 2 3 4 5 6 7 8 9 10 Next Last
LANSDALE Semiconductor, Inc.
ML13175/ML13176
Pin Symbol
1&4
Osc 1,
Osc 4
10k
1
0sc 1
PIN FUNCTION DESCRIPTIONS
Internal Equivalent
Circuit
Description/External
Circuit Requirements
CCO Inputs
VCC
The oscillator is a current controlled type. An external oscillator
coil is connected to Pins 1 and 4 which forms a parallel
10k
resonance LC tank circuit with the internal capacitance of the
IC and with parasitic capacitance of the PC board. Three
4
Osc 4
base–emitter capacitances in series configuration form the
capacitance for the parallel tank. These are the base–emitters
at Pins 1 and 4 and the base–emitter of the differential amplifier.
The equivalent series capacitance in the differential amplifier is
varied by the modulating current from the frequency control
circuit (see Pin 6, internal circuit). A more thorough discussion
is found in the Applications Information section.
5
VEE
6
ICont
7
PDout
VEE
5
Subcon
VEE
VEE
VCC
Reg
6
ICont
Supply Ground (VEE)
In the PCB layout, the ground pins (also applies to Pins 10 and
15) should be connected directly to chassis ground. Decoupling
capacitors to VCC should be placed directly at
the ground returns.
Frequency Control
For VCC = 3.0 Vdc, the voltage at Pin 6 is approximately 1.55
Vdc. The oscillator is current controlled by the error current from
the phase detector. This current is amplified to drive the current
source in the oscillator section which controls the frequency of
the oscillator. Figures 9 and 10 show the fosc versus ICont,
Figure 5 shows the fosc versus ICont at – 40°C, + 25°C and
+ 85°C for 320 MHz. The CCO may be FM modulated as shown
in Figure 17, ML13176 320 MHz FM Transmitter. A detailed
discussion is found in the Applications Information section.
VCC
4.0k
4.0k
PDout
7
Phase Detector Output
The phase detector provides ± 30 µA to keep the CCO locked at
the desired carrier frequency. The output impedance of the
phase detector is approximately 53 k. Under closed loop
conditions there is a DC voltage which is dependent upon the
free running oscillator and the reference oscillator frequencies.
The circuitry between Pins 7 and 6 should be selected for
adequate loop filtering necessary to stabilize and filter the loop
response. Low pass filtering between Pin 7 and 6 is needed so
that the corner frequency is well below the sum of the divider
and the reference oscillator frequencies, but high enough to
allow for fast response to keep the loop locked. Refer to the
Applications Information section regarding loop filtering and FM
modulation.
Page 3 of 16
www.lansdale.com
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