Datasheet

Board Connections and Configuration www.ti.com
• Higher Input and / or Output Voltage Modifications
– Although the standard LM3423 evaluation board is designed to operate at input and output voltages
up to 35V, the device is capable of operating with input and output voltages up to 75V. Operation
up to 75V can be achieved by changing the voltage ratings of the input capacitors (C1, C8, C17),
output capacitors (C4, C7, C11, C16), and transistors Q4, Q5, Q7. For output voltages greater than
35V the OVP resistors R20 and R22 will need to be adjusted.
3 Board Connections and Configuration
Connecting the evaluation board to a power supply and load is accomplished through banana-plug type
connectors (refer to Table 1).
Table 1. LM3423 Eval Board Connectors
Connector Designation Function or Use
V
IN
Power supply (Positive) primary connection
GND Power supply (Negative) primary connection
LED+ Connect to anode of LED.
LED- Connect to cathode of LED.
Configuration of the evaluation board is accomplished through the use of on-board jumpers (refer to
Table 2).
Table 2. LM3423 Evaluation Board Jumpers
Jumper Designation Function or Use Notes
J1 Enable (EN)
OPEN: Disables LM3423.
CLOSED: Enables LM3423.
J2 Current Limit (IS)
OPEN: Disables MOSFET RDS(ON) current sensing "Q5".
CLOSED: Enables MOSFET RDS(ON) current sensing "Q5".
J3 Current Limit (IS)
OPEN: Disables external sense resistor MOSFET current sensing
"Q5".
CLOSED: Enables external sense resistor MOSFET current
sensing "Q5".
J4A, J4B Current Limit (IS): Must be used in conjunction with jumper J2.
OPEN: Enables sensing MOSFET switch current across sense
resistor "R6".
CLOSED: Disables sensing MOSFET switch current across sense
resistor "R6".
J5 PWM Dimming
OPEN: Enables high-side PWM dimming.
CLOSED: Disables high-side PWM dimming.
J6 Fault Timer (FLT)
OPEN: External capacitor programs fault condition time to set flag
(FLT).
CLOSED: Disables fault timer and flag (FLT).
Test points in the form of clip-on pegs are available to the user for making measurements on the LM3423
evaluation board (see Table 3).
2
AN-1907 LM3423 Buck-Boost Configuration Evaluation Board SNVA376A–December 2008–Revised May 2013
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