Техническая Спецификация для Texas Instruments Evaluation Board for the LM20343 LM20343EVAL/NOPB LM20343EVAL/NOPB
Модели
LM20343EVAL/NOPB
Powering and Loading Considerations
3.2
Powering Up
It is suggested that the load power be kept low during the first power up. Set the current limit of the input
source to provide about 1.5 times the anticipated wattage of the load. Once the device is powered up,
immediately check for 3.3 volts at the output.
source to provide about 1.5 times the anticipated wattage of the load. Once the device is powered up,
immediately check for 3.3 volts at the output.
A quick efficiency check is the best way to confirm that everything is operating properly. If something is
amiss you can be reasonably sure that it will affect the efficiency adversely. Few parameters can be
incorrect in a switching power supply without creating losses and potentially damaging heat.
amiss you can be reasonably sure that it will affect the efficiency adversely. Few parameters can be
incorrect in a switching power supply without creating losses and potentially damaging heat.
3.3
Over Current Protection
The evaluation board is configured with cycle-by-cycle over-current protection. This function is completely
contained in the LM20343. The peak current is limited to approximately 5.2A.
contained in the LM20343. The peak current is limited to approximately 5.2A.
Table 1. Connection Descriptions
Terminal Silkscreen
Description
VIN
This terminal is the input voltage to the device. The evaluation board will operation over the input
voltage range of 4.5V to 25V. This voltage is limited due to the voltage rating of the input capacitors.
voltage range of 4.5V to 25V. This voltage is limited due to the voltage rating of the input capacitors.
GND
These terminals are the ground connections to the device. There are three different GND connections
on the PCB. J2 should be used for the input supply, J4 should be used for the load, and J8 should be
used for low power signal connections such as ENABLE.
on the PCB. J2 should be used for the input supply, J4 should be used for the load, and J8 should be
used for low power signal connections such as ENABLE.
VOUT
This terminal connects to the output voltage of the power supply and should be connected to the load.
ENABLE
This terminal connects to the enable pin of the device. This terminal can be left floating or driven
externally. If driven externally, a voltage typically less than 1.2V will disable the device. The operating
voltage for this pin should not exceed 5.5V. The absolute maximum voltage rating on this pin is 6V.
externally. If driven externally, a voltage typically less than 1.2V will disable the device. The operating
voltage for this pin should not exceed 5.5V. The absolute maximum voltage rating on this pin is 6V.
SS/TRK
This terminal provides access to the SS/TRK pin of the device. Connections to this terminal are not
needed for most applications. The feedback pin of the device will track the voltage on the SS/TRK pin
if it is driven with an external voltage source that is below the 0.8V reference. The voltage on this pin
should not exceed 5.5V during normal operation. The absolute maximum voltage rating on this pin is
6V.
needed for most applications. The feedback pin of the device will track the voltage on the SS/TRK pin
if it is driven with an external voltage source that is below the 0.8V reference. The voltage on this pin
should not exceed 5.5V during normal operation. The absolute maximum voltage rating on this pin is
6V.
PGOOD
This terminal connects to the power good output of the device. There is an option to connect this pin
to VOUT or VCC through a 10 k
to VOUT or VCC through a 10 k
Ω
pull-up resistor. The voltage on this pin should not exceed 5.5V
during normal operation and has an absolute maximum voltage rating of 6V.
JP1
This terminal block selects the pull-up voltage for the PGOOD pin to be either VCC or VOUT. An
external voltage source for PGOOD may be supplied by connecting to the center terminal. The
voltage applied to PGOOD should not exceed 5.5V during normal operation and has an absolute
maximum voltage rating of 6V.
external voltage source for PGOOD may be supplied by connecting to the center terminal. The
voltage applied to PGOOD should not exceed 5.5V during normal operation and has an absolute
maximum voltage rating of 6V.
SW
This terminal allows easy probing of the switch node. Do not apply any external voltage source to this
pin.
pin.
TP1 (VOUT)
This is a oscilloscope probe connector point used to measure the output ripple and transient
response. It is design to work with most Tektronix oscilloscope probes and is the recommended
measurement point for evaluating AC performance.
response. It is design to work with most Tektronix oscilloscope probes and is the recommended
measurement point for evaluating AC performance.
3
SNVA326B – May 2008 – Revised May 2013
AN-1792 LM20343 Evaluation Board
Copyright © 2008–2013, Texas Instruments Incorporated