MAX5954LEVKIT Maxim Integrated, MAX5954LEVKIT Datasheet - Page 5

• Manufacturer Part Number: MAX5954LEVKIT
• Description: Power Management IC Development Tools Evaluation Kit/Evaluation System for the MAX5954L/MAX5954A
• Manufacturer: Maxim Integrated
• Series: MAX5954r

The MAX5954L EV kit features green LEDs connected
to the 12V, 3.3V, and 3.3V-auxiliary outputs that indi-
cate if the respective output is currently powered. Red
test points for the 12V and 3.3V outputs, various PCI
Express signals, and other circuit signals (such as the
gate drive of each MOSFET) have been provided for
probing on the EV kit board. All of the EV kit’s black test
points are GND points.
The EV kit also features PC board pads for installing
external resistors and capacitors near each MOSFET
gate terminal to slow the MOSFETs gate-turn-on time.
Surface-mount 0805 case size components can be
installed at these locations. See Figure 3 for each of the
MOSFETs’ gate reference designators.
When adding capacitance to the gates of N1 and N2,
ensure that adequate startup time (t
successfully power up, the 5µA gate-charge current
must be able to bring the gate voltages of N1 and N2
above their maximum PWRGD thresholds before t
has elapsed. The maximum PWRGD threshold for 12V
MOSFET N1 is 4.8V above V
3.3V MOSFET N2 is 4.5V above V
required to reach these thresholds is
The EV kit can be reconfigured for evaluating a x1, x4,
or x8 PCI Express single hot-plug design by replacing
current-sense resistor R1. Consult the appropriate PCI
Express specification or Table 1 in the MAX5954L IC
data sheet for selecting other designs. PC board pads
are provided to demonstrate the MAX5954L hot-plug
features without using the PCI Express x16 connector.
For evaluating external DC loads, the cables connect-
ing the 12V and 3.3V outputs to the external DC load
must be rated for at least 10A and be shorter than 12in.
Additionally, current-sense resistors R1 and R15 are
configured for the maximum allowable output current
on the 12V and 3.3V outputs. These resistors should be
reconfigured only for lower output currents.
The MAX5954L EV kit features a MAX7313 16-port I/O
expander (U2) and PC board pads for interfacing to a
user’s SMBus system. Resistors R20–R25 configure the
MAX7313 SMBus serial address. The MAX7313 can be
used to enable/disable the EV kit’s main outputs and
auxiliary 3.3V output independently. See the MAX7313
Input/Output Expander and SMBus Interface section
for more details.
Several jumper and switch selections in the following
tables display the functions provided by the MAX5954L
EV kit.
total gate capaci
MAX5954L Evaluation Kit/Evaluation System
Jumper and Switch Selection
tan
_______________________________________________________________________________________
ce PWRGD threshold voltage
×
5µ
A
12VIN
, and the threshold for
SU
3.3VIN
) is allowed. To
. The time
SU
The MAX5954L EV kit features a jumper that can simu-
late a PCI Express x16 card being plugged into con-
nector J1. Jumper JU1 is used to provide a presence-
detect function for the channel. An external load (resis-
tive and capacitive) must be connected to the chan-
nel’s output PC board pads to simulate a real PCI
Express card. Table 1 lists the various jumper options.
The MAX5954L EV kit features two switches to
enable/disable the 12V/3.3V main and 3.3V-auxiliary
outputs. The switches can also be used to reset the
channel when it has latched off after a fault has
occurred. Table 2 lists the various switch options.
Table 1. Channel Presence-Detect
Functions
*When using a real PCI Express card, this jumper’s shunt must
be removed so that the card has control of the presence
detection.
Table 2. Channel Switch Functions
*When using a real PCI Express card, this jumper’s shunt must
be removed so that the card has control of the presence
detection.
JUMPER
SWITCH
SW3
SW3
SW2
SW2
JU1
JU1
Installed
SHUNT
SWITCH
None*
STATE
On
Off
On
Off
Channel Enable/Disable Switches
PRES-DET pin
pulled low
PRES-DET pin
pulled high
MAX5954L PIN
CONNECTION
ON pin pulled
high
ON pin pulled low
AUXON pin pulled
high
AUXON pin pulled
low
MAX5954L PIN
CONNECTION
Presence Detect
PCI Express card
inserted in channel
No PCI Express card
in channel
EV KIT OPERATION
Enable main
outputs
Disable main
outputs
Enable 3.3V-
auxiliary output
Disable 3.3V-
auxiliary output
SIMULATED
OPERATION
MAX5954L
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