74HCT9046AN Philips, 74HCT9046AN Datasheet - Page 11

• Manufacturer Part Number: 74HCT9046AN
• Description: PLL with bandgap controlled VCO
• Manufacturer: Philips

Philips Semiconductors
1999 Jan 11
PLL with bandgap controlled VCO
The pulse overlap of the up and down signals (typically 15 ns).
a. Response with traditional voltage-switch charge-pump PC2
(1) Due to parasitic capacitance on PC2
(2) Backlash time (dead zone).
b. Response with current switch charge-pump PC2
VCO IN
Fig.11 The response of a locked-loop in the vicinity of the zero crossing of the phase error.
2.75
2.50
2.25
SIG IN
UP
DOWN
CURRENT AT
PC2 OUT
PC2
PCP OUT
COMP IN
VCO OUT
25
OUT
/VCO
(1)
IN
OUT
(2)
a.
0
OPC IN
.
phase error (ns)
OUT
(1)
Fig.10 Timing diagram for PC2.
as applied in the HCT9046A.
OUT
25
high impedance OFF state,
(zero current)
(4046A).
11
VCO IN
2.75
2.50
2.25
25
0
b.
phase error (ns)
MBD047 - 1
74HCT9046A
Product specification
MBD043
25