SMH4042 Datasheet, PDF (17/28 Pages) Summit Microelectronics, Inc. – Hot Swap™ Controller

SMH4042
CompactPCI Applications Aid
Power Switching Options
The figures below illustrate four possible methods for wiring the SMH4042. In the first example both power-FETs are
connected to a single VGATE output. This should be used when the design requires the backend voltages to be
powered-up simultaneously. In the second example both VGATE outputs are being used so that the 3.3V slew lags
the 5V slew. The two bottom circuits illustrate the wiring for single power supply boards. Note how the VSEL pin is
biased differently for the two applications.
+5V
±5%
5A max
+3.3V ±.3V
7.6A max
.01Ω
D
G ^100Ω
S
VCC
CBI_5
VGATE5
CARD_5V_MON
S
G
D
.0065Ω
CARD_3V_MON
100Ω
VGATE3
47nF
VSEL
CBI_3
HST_3V_MON
Dual Voltage, Single Slew Rate Implementation
+5V
±5%
5A max
+3.3V ±.3V
7.6A max
.01Ω
D
100Ω
G
47nF
S
VCC
CBI_5
VGATE5
CARD_5V_MON
S
G ^100Ω
47nF
D
.0065Ω
CARD_3V_MON
VSEL
VGATE3
CBI_3
HST_3V_MON
Dual Voltage, Dual Slew Rate Implementation
+5V
±5%
5A max
.01Ω
VCC
CBI_5
D
G ^100Ω
VGATE5
47nF
S
CARD_5V_MON
VSEL
CARD_3V_MON
VGATE3
CBI_3
HST_3V_MON
Single 5Volt Implementation
Note: If the backend circuits
that are being powered are
not sufficiently decoupled,
the value of this resistor
may need to be increased to
as high as 10K ohm
VCC
CBI_5
VGATE5
+3.3V ±.3V
7.6A max
CARD_5V_MON
S
G ^100Ω
47nF
D
.0065Ω
CARD_3V_MON
VSEL
VGATE3
CBI_3
HST_3V_MON
Single 3.3Volt Implementation
2037 ILL26.2
Figure 5. Four power switching implementations
2037-07 9/23/99
17