TLC2932_15 Datasheet, PDF (2/29 Pages) Texas Instruments – HIGH-PERFORMANCE PHASE-LOCKED LOOP

TLC2932
HIGH-PERFORMANCE PHASE-LOCKED LOOP
SLAS097E – SEPTEMBER 1994 – REVISED MAY 1997
Terminal Functions
TERMINAL
NAME
NO.
FIN – A
4
FIN – B
5
LOGIC GND
7
LOGIC VDD
1
NC
8
PFD INHIBIT
9
PFD OUT
6
BIAS
13
SELECT
2
VCO IN
12
VCO INHIBIT
10
VCO GND
11
VCO OUT
3
VCO VDD
14
I/O
DESCRIPTION
I Input reference frequency f(REF _IN) is applied to FIN – A.
I 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.
I PFD inhibit control. When PFD INHIBIT is high, PFD output is in the high-impedance state, see Table 3.
O PFD output. When the PFD INHIBIT is high, PFD output is in the high-impedance state.
I Bias supply. An external resistor (RBIAS) between VCO VDD and BIAS supplies bias for adjusting the
oscillation frequency range.
I 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.
I VCO control voltage input. Nominally the external loop filter output connects to VCO IN to control VCO
oscillation frequency.
I VCO inhibit control. When VCO INHIBIT is high, VCO OUT is low (see Table 2).
GND for VCO.
O 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
Bias Resistor (RBIAS)
1/2 VDD
VCO Control Voltage (VCO IN)
Figure 1. VCO Oscillation Frequency
2
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