LTC1646
W U U
APPLICATIO S I FOR ATIO
U
Table 5. R1 and R2 Resistor Values vs Precharge Voltage
Other CompactPCI Applications
V
R1
R2
V
R1
R2
PRECHARGE
PRECHARGE
The LTC1646 can be easily configured for applications
whereno5Vsupplyispresentbysimplytying the5VIN and
5VSENSE pins to the 3VIN pin and tying the 5VOUT pin to the
3VOUT pin (Figure 10).
1.5V
1.4V
1.3V
1.2V
1.1V
1V
18Ω
18Ω
18Ω
18Ω
18Ω
18Ω
9.09Ω
7.15Ω
5.36Ω
3.65Ω
1.78Ω
0Ω
0.9V
0.8V
0.7V
0.6V
0.5V
16.2Ω
14.7Ω
12.1Ω
11Ω
1.78Ω
3.65Ω
5.11Ω
7.15Ω
9.09Ω
9.09Ω
LTC1646*
PRECHARGE DRIVE
LTC1646*
GND
6
GND PRECHARGE
13
DRIVE
14
13
14
6
18Ω
1k
18Ω
1k
4.7nF
4.7nF
R2
12Ω
12Ω
R1
R2
MMBT2222A
R1
MMBT2222A
PRECHARGE OUT
PRECHARGE OUT
3V
IN
3V
IN
R1
R1 + R2
• 1V
V
=
V
=
• 1V
PRECHARGE
PRECHARGE
R1 + R2
R1
1646 F08
1646 F09
*ADDITIONAL DETAILS OMITTED FOR CLARITY
*ADDITIONAL DETAILS OMITTED FOR CLARITY
Figure 8. Precharge Voltage <1V Application Circuit
Figure 9. Precharge Voltage >1V Application Circuit
COMPACT PCI COMPACT PCI
BACKPLANE
CONNECTOR
(MALE)
CIRCUIT CARD
CONNECTOR
(FEMALE)
Z1
0.005Ω
1%
IRF7413
1
2
3.3V
7.6A
OUT
3.3V
3
4
0.1µF
LONG 3.3V
1.8Ω
10Ω
V(I/O)
1k
0.010µF
0.1µF
8
3V
IN
9
10
7
12
IN
11
5
1.2k
3V
GATE 3V
5V
5V
5V
OUT
SENSE
OUT
SENSE
1k
10k
3V
2
1
15
3
BD_SEL#
OFF/ON
FAULT
TIMER
V(I/O)
3k
3k
OUT
LTC1646
4
3k
HEALTHY#
PCI_RST#
PWRGD
16
RESETIN
RESETOUT
GND
6
PRECHARGE
13
DRIVE
14
18Ω
1k
4.7nF
18Ω
12Ω
3V
IN
GROUND
I/O PIN 1
PRECHARGE OUT
MMBT2222A
1V ±10%
3.3V
RESET#
1k
I
= ± 55mA
OUT
3V
IN
10Ω
DATA LINE EXAMPLE
I/O
PCI
BRIDGE
(21154)
DATA BUS
DATA BUS
Z1: BZX84C6V2
1646 F10
Figure 10. 3.3V Supply Only Typical Application
1646fa
15
Linear [ Linear ]
