Channel A Enable/Disable Switches

The MAX5946L EV kit features two switches to

enable/disable the 12V/3.3V main and 3.3V auxiliary

channel A outputs. The switches can also be used to

reset a channel that has latched off after a fault has

Channel B Enable/Disable Switches

The MAX5946L EV kit features two switches to

enable/disable the 12V/3.3V main and 3.3V auxiliary

channel B outputs. The switches can also be used to

reset a channel that has latched off after a fault has

occurred. Table 3 lists the various switch options.

Control Methods, Other Configurations,

and I/O Expander

Fault Resetting

The MAX5946L EV kit features two slide switches to

reset a latched fault at each channel. The switch will

reset the EV kit and unlatch faults when toggled from

ON to OFF and back to ON. See Table 2 for resetting

channel A or Table 3 for channel B. Refer to the

MAX5946L data sheet for additional functions of the

MAX5946L ONA or ONB pins.

Fault Timeout and POR Periods

The MAX5946L fault timeout period is configured for

10ms and can be reconfigured to a new timeout period

by installing surface-mount resistor R5. The MAX5946L

POR timeout period is configured for 160ms; however,

a new POR timeout period can be reconfigured by

installing surface-mount resistor R27. Refer to the

MAX5946 data sheet’s Applications Information section

to select the values of resistors R5 or R27.

Forced-On Inputs

Either channel A or B’s PCI Express slot can be forced

to turn on regardless of the MAX5946L logic status

inputs. To force channel A on, install surface-mount

resistor R28; to force channel B on, install surface-

mount resistor R8. Typical values are less than 1k

Ω.

Current Limiting

The MAX5946L EV kit can evaluate other current-limit

configurations for the 12V and 3.3V main outputs of

either channel. Resistors R1 and R2 set the 12V current

limit for channels A and B, respectively. Resistors R3

and R4 set the 3.3V current limit for channels A and B,

respectively.

The 3.3V auxiliary current limit is fixed at 470mA (typ)

and is not reconfigurable. Refer to the MAX5946 IC

data sheet for information on selecting other current-

limit resistors.

Evaluating Other MAX5946 Hot-Plug Controllers

The MAX5946L EV kit can be used to evaluate the

MAX5946A. Replace U1 with the MAX5946A IC.

MAX5946L Evaluation Kit/Evaluation System

_______________________________________________________________________________________

5

Table 2. Channel A Switch Functions

SWITCH

SWITCH STATE

MAX5946L PIN CONNECTION

MAX5946L OPERATION

SW5

On

ONA pin pulled high

Enable channel A main outputs

SW5

Off

ONA pin pulled low

Disable channel A main outputs

SW6

On

AUXONA pin pulled high

Enable channel A +3.3V auxiliary output

SW6

Off

AUXONA pin pulled low

Disable channel A +3.3V auxiliary output

Table 3. Channel B Switch Functions

SWITCH

SWITCH STATE

MAX5946L PIN CONNECTION

MAX5946L OPERATION

SW3

On

ONB pin pulled high

Enable channel B main outputs

SW3

Off

ONB pin pulled low

Disable channel B main outputs

SW4

On

AUXONB pin pulled high

Enable channel B +3.3V auxiliary output

SW4

Off

AUXONB pin pulled low

Disable channel B +3.3V auxiliary output