Texas Instruments Evaluation Board for the LM5051 LM5051MAEVAL/NOPB LM5051MAEVAL/NOPB Datenbogen
Produktcode
LM5051MAEVAL/NOPB
-5
0
5
10
15
20
25
-2
0
2
4
6
8
10
12
14
VO
L
T
S
(V)
TIME ( s)
INPUT B- Shorted
INPUT A-
INPUT B-
GATE Q1
GATE Q2
INPUT B-
GATE Q1
GATE Q2
X.XXX V
2.000 A
PRODIGIT 3314
³$´
48.0V @ 5A
³%´
48.5V @ 3A
Inductive Kick-Back Protection
Figure 1. Typical Board Connections
4
Inductive Kick-Back Protection
Diode D1 and capacitor C3 serve as inductive kick-back protection to limit negative transient voltage
spikes generated on the input when the INPUT A supply voltage is abruptly taken to zero volts. Diode D2
and capacitor C4 serve the same protective function on the INPUT B supply voltage.
spikes generated on the input when the INPUT A supply voltage is abruptly taken to zero volts. Diode D2
and capacitor C4 serve the same protective function on the INPUT B supply voltage.
Diode D4 and capacitors C5/C6 serve as inductive kick-back protection to limit positive transient voltage
spikes generated on the output when an input supply voltage is abruptly taken to zero volts.
spikes generated on the output when an input supply voltage is abruptly taken to zero volts.
5
OR-ing Transfer
An example of OR-ing transfer is shown in
. In this example one 48.5V supply (INPUT B) is
powering a 2A load at the output, while a 48.0V supply (INPUT A) is connected, but is idle. The OR-ing
transfer begins when the 48.5V supply is shorted (INPUT B- is shorted to INPUT B+). This short causes
reverse current through the MOSFET (Q2) and creates the required voltage (V
transfer begins when the 48.5V supply is shorted (INPUT B- is shorted to INPUT B+). This short causes
reverse current through the MOSFET (Q2) and creates the required voltage (V
SD(REV)
+
Δ
V
SD(REV)
) on the
LM5051 INN pin (U2) that will immediately cause the discharge the gate of the Q2 MOSFET.
Figure 2. Forward and Reverse Waveforms
2
AN-2148 LM5051MAEVAL Evaluation Board
SNVA483B – October 2011 – Revised May 2013
Copyright © 2011–2013, Texas Instruments Incorporated