TLC2932
HIGH-PERFORMANCE PHASE-LOCKED LOOP
SLAS097E – SEPTEMBER 1994 – REVISED MAY 1997
Terminal Functions
TERMINAL
NAME
FIN – A
FIN – B
LOGIC GND
LOGIC VDD
NC
PFD INHIBIT
PFD OUT
BIAS
SELECT
VCO IN
VCO INHIBIT
VCO GND
VCO OUT
VCO VDD
NO.
4
5
7
1
8
9
6
13
2
12
10
11
3
14
O
I
O
I
I
I
I
I/O
I
I
DESCRIPTION
Input reference frequency f(REF IN) is applied to FIN – A.
Input for VCO external counter output frequency f(FIN – B). FIN – B is nominally provided from the external
counter.
GND for the internal logic.
Power supply for the internal logic. This power supply should be separate from VCO VDD to reduce
cross-coupling between supplies.
No internal connection.
PFD inhibit control. When PFD INHIBIT is high, PFD output is in the high-impedance state, see Table 3.
PFD output. When the PFD INHIBIT is high, PFD output is in the high-impedance state.
Bias supply. An external resistor (RBIAS) between VCO VDD and BIAS supplies bias for adjusting the
oscillation frequency range.
VCO output frequency select. When SELECT is high, the VCO output frequency is
×
1/2 and when low, the
output frequency is
×
1, see Table 1.
VCO control voltage input. Nominally the external loop filter output connects to VCO IN to control VCO
oscillation frequency.
VCO inhibit control. When VCO INHIBIT is high, VCO OUT is low (see Table 2).
GND for VCO.
VCO output. When the VCO INHIBIT is high, VCO output is low.
Power supply for VCO. This power supply should be separated from LOGIC VDD to reduce cross-coupling
between supplies.
detailed description
VCO oscillation frequency
The VCO oscillation frequency is determined by an external resistor (R
BIAS
) connected between the VCO V
DD
and the BIAS terminals. The oscillation frequency and range depends on this resistor value. The bias resistor
value for the minimum temperature coefficient is nominally 3.3 kΩ with 3-V at the VCO V
DD
terminal and
nominally 2.2 kΩ with 5-V at the VCO V
DD
terminal. For the lock frequency range refer to the recommended
operating conditions. Figure 1 shows the typical frequency variation and VCO control voltage.
VCO Oscillation Frequency Range
VCO Oscillation Frequency (f osc )
Bias Resistor (RBIAS)
1/2 VDD
VCO Control Voltage (VCO IN)
Figure 1. VCO Oscillation Frequency
2
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