Texas Instruments TPS54340 Step-Down Converter Evaluation Module TPS54340EVM-182 TPS54340EVM-182 데이터 시트
제품 코드
TPS54340EVM-182
Time = 20
s/div
m
200 mA/div
2 V/div
20 mV/div
C3: V
ac coupled
OUT
C1: SW
C4: IL
No Load
EN Floating
EN Floating
C3
C4
V
= 5.5 V
V
= 5 V
IN
OUT
Time = 40
s/div
m
2 V/div
VIN
I
= 1 A
EN Floating
OUT
VOUT
Time = 200 µs/div
5
V/d
iv
2
V/d
iv
2
V/d
iv
C1: V
IN
C2: EN
C3: V
OUT
Time = 1 ms/div
5
V/
d
iv
2
V/d
iv
2
V/d
iv
C1: V
IN
C2: EN
C3: V
OUT
Test Setup and Results
2.9
Shutdown
The shutdown waveforms are shown in
and
. The input voltage for these plots is 12 V
with a 3.5-A resistive load. The top trace shows V
IN
, the middle trace shows EN, and the bottom trace
shows V
OUT
. In
the input voltage is removed, and when the input falls below the undervoltage
lockout threshold, the TPS54340 shuts down and the output falls to ground.
In
, the input voltage is held at 12 V, and EN is shorted to ground. When EN is grounded, the
TPS54340 is disabled, and the output voltage discharges to ground.
Figure 19. Shutdown Relative to V
IN
Figure 20. Shutdown Relative to EN
2.10 Low Dropout Operation
For improved low dropout operation, the TPS54340 includes a small integrated low-side MOSFET to pull
SW to GND when the BOOT to SW voltage drops below 2.1 V. This recharges the BOOT capacitor for
driving the high-side MOSFET.
SW to GND when the BOOT to SW voltage drops below 2.1 V. This recharges the BOOT capacitor for
driving the high-side MOSFET.
shows the steady state operation and
shows the start
up and shutdown in a low dropout condition.
Figure 21. Low Dropout Operation
Figure 22. Low Dropout Start Up and Shutdown
11
SLVU794A – October 2012 – Revised February 2013
Using the TPS54340 Step-Down Converter Evaluation Module
Copyright © 2012–2013, Texas Instruments Incorporated