SLUU150 – February 2003
12
Evaluation Modules for Simple –48-V Hot Swap Controllers
4
Using the Evaluation Module to Evaluate the TPS2390/1
Procedures similar to the steps of Section 3.2.2 for functional test of the EVM can also be used
to continue evaluation of the TPS2390 and TPS2391 hot swap controllers. Additional details
about the EVM features are provided in this section.
The ENABLE switch can be used to enable and disable power to the load (i.e., the VOUT+ and
VOUT– terminals), when the POWER switch is in the ON position.
Also, with the ENABLE switch in the ON position, the POWER switch can be toggled ON and
OFF to simulate hot swap events with the device set up to automatically power up the load.
4.1
Test Points
The –48-V hot swap EVM contains the test points listed in Table 4, for waveform and voltage
monitoring.
Table 4. Test Points
TEST
POINT
SIGNAL
NAME
DESCRIPTION
TP1
FAULT
Load fault output of the TPS2390/91. On the EVM, this signal drives the red LED.
TP2
EN
Device enable input to turn on/off power to the load.
TP3
FLTTIME
Fault timing waveform of the TPS2390/91.
TP4
IRAMP
Current ramp control output waveform.
TP5
–VIN
Negative supply input and reference pin for the TPS2390/91. On the EVM, this is connected to
–48V_IN.
TP6
ISENS
Current sense input of the controller.
TP7
GATE
Gate drive for external FET Q1.
TP8
–VIN
Secondary test point on device reference node.
TP9
48V RTN
The high side of input power to the EVM. When used in conjunction with a lab supply, this connects
TP11
–48V_RTN
The high side of in ut ower to the EVM. When used in conjunction with a lab su
ly, this connects
to the (+) jack.
TP10
48V IN
The low side of input power to the EVM. When used in conjunction with a lab supply, this connects to
TP12
–48V_IN
The low side of in ut ower to the EVM. When used in conjunction with a lab su
ly, this connects to
the (–) jack.
TP13
VOUT
High side of s itched (load) o tp t po er
TP15
VOUT+
High side of switched (load) output power.
TP14
VOUT
Lo
side of s itched (load) o tp t po er
TP16
VOUT–
Low side of switched (load) output power.
4.2
Load Capacitors
Capacitor patterns C6 and C7 are available on the EVM for installation of components to
represent the module input bulk capacitance; i.e., the load capacitance seen by the hot swap
interface circuit. As supplied from the factory, the EVM contains a 100-
µ
F aluminum electrolytic
installed at C6. Further customization to approximate the user’s application can be done using
either C6 or C7. When installing capacitors in these mounting locations, care should be taken to
observe the polarity marking on the PCB silkscreen, and to use appropriately rated capacitors
for voltage withstanding. Generally, telecom applications should use 100-V minimum rated
capacitors.
Banana jacks J3 and J4 are also connected across the output terminals, in parallel with C6 and
C7. These jacks can be used to connect additional loads to the EVM board.
