Rainbow Electronics MAX5960 - Manual (Page 13)

MAX5959/MAX5960
Quad PCI Express, Hot-Plug Controllers
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Pin Description (continued)
PIN NAME FUNCTION
43 12SD+
Slot D 12V Positive Current-Sense Input. Connect the positive terminal of the current-sense resistor to
12SD+ using the Kelvin-sensing technique to ensure accurate current sensing.
44 3.3GD
Slot D 3.3V Gate-Drive Output. Connect 3.3GD to the gate of slot D’s 3.3V MOSFET. At power-up,
V
3.3GD
is charged to 5.5V above the 3.3V supply by a constant current derived from V
12VIN
. V3.3GD ’s
rise time is determined by the external gate capacitance.
45 3.3SD-
Slot D 3.3V Negative Current-Sense Input. Connect to the negative side of the sense resistor using the
Kelvin-sensing technique to ensure accurate current sensing.
46 3.3SD+
Slot D 3.3V Positive Current-Sense Input. Connect the positive side of the current-sense resistor to
3.3SD+ using the Kelvin-sensing technique to ensure accurate current sensing.
47 PRES-DETB
Slot B Present-Detect Input. PRES-DETB accepts inputs from PRSNT#_# on a PCIe connector.
PRES-DETB has an internal 50k Ω pullup to 3.3VAUXIN. When PRES-DETB is low, the outputs follow the
command from ONB and AUXONB after a 4ms debounced time. When PRES-DETB goes from low to
high, all outputs of the respective slot shut down with no delay.
48 FONB
Slot B Forced-On Input. FONB has a 50k Ω internal pullup to 3.3VAUXIN. A logic-low on FONB turns on
all slot B outputs as long as the power inputs are within their operating range, regardless of the status of
the other input signals. Leave
FONB unconnected for normal operation.
49 PRES-DETA
Slot A Present-Detect Input. PRES-DETA accepts inputs from PRSNT#_# on a PCIe connector.
PRES-DETA has an internal 50k Ω pullup to 3.3VAUXIN. When PRES-DETA is low, the outputs follow the
command from ONA and AUXONA after a 4ms debounced time. When PRES-DETA goes from low to
high, all outputs of the respective slot shut down with no delay.
50 FONA
Slot A Forced-On Input. FONA has a 50k Ω internal pullup to 3.3VAUXIN. A logic-low on FONA turns on
all slot A outputs as long as the power inputs are within their operating range, regardless of the status of
the other input signals. Leave
FONA unconnected for normal operation.
51 OUTPUT4 Digital Output 4. 4ms debounced digital output of INPUT4.
52 INPUT4 Digital Logic Gate Input 4
53 OUTPUT3 Digital Output 3. 4ms debounced digital output of INPUT3.
54 INPUT3 Digital Logic Gate Input 3
55 ONA
Slot A 12V and 3.3V Outputs Enable. A logic-high at ONA turns on the 12V and 3.3V outputs of slot A
(see Table 2).
56 AUXONA Slot A 3.3V Auxiliary Output Enable. A logic-high at AUXONA turns on the slot A auxiliary output.
57 12SA+
Slot A 12V Positive Current-Sense Input. Connect the positive terminal of the current-sense resistor to
12SA+ using the Kelvin-sensing technique to ensure accurate current sensing.
58 12SA-
Slot A 12V Negative Current-Sense Input. Connect 12SA- to the negative side of the current-sense
resistor using the Kelvin-sensing technique to ensure accurate current sensing.
59 12GA
Slot A 12V Gate-Drive Output. Connect 12GA to the gate of slot A’s 12V MOSFET. At power-up, V 12GA
is raised to the internal charge-pump voltage level by a constant current.
60 3.3SA+
Slot A 3.3V Positive Current-Sense Input. Connect the positive side of the current-sense resistor to
3.3SA+ using the Kelvin-sensing technique to ensure accurate current sensing.
62 3.3SA-
Slot A 3.3V Negative Current-Sense Input. Connect to the negative side of the sense resistor using the
Kelvin-sensing technique to ensure accurate current sensing.