Datasheet

SLUU111 – June 2002
9
1-MHz, 3.3-V, High-Efficiency Synchronous Buck Converter With TPS43000 PWM Controller
3 Test Results
3.1 Efficiency Curves
Efficiency tested at different loads and input voltages is shown in Figure 4. The maximum
efficiency is as high as 94% at 0.5 A output. The light-load efficiency is improved due to the
PFM operation mode.
3.2 Typical Operation Waveform
Typical operating waveforms are shown in Figure 5 with V
IN
= 4.5 V and I
OUT
= 2 A.
0 0.5 1.0 1.5 2.0
65
70
75
80
85
90
95
EFFICIENCY
vs
LOAD CURRENT AND INPUT VOLTAGE
Figure 3.
V
IN
= 4.5 V
V
IN
= 8.5 V
V
IN
= 6.5 V
Efficiency – (%)
I
OUT
– Load Current – A
OPERATING WAVEFORMS
DURING OVERLOAD
V
IN
= 4.5 V
I
OUT
= 2 A
V
OUT
(2 V/div)
V
DS(Q1)
(5 V/div)
I
OUT
(5 A/div)
Figure 4.
t – Time – 500 ns / div