MAX1639 Datasheet, PDF (4/13 Pages) Maxim Integrated Products – High-Speed Step-Down Controller with Synchronous Rectification for CPU Power

High-Speed Step-Down Controller with
Synchronous Rectification for CPU Power
__________________________________________Typical Operating Characteristics
(T_A = +25°C, using the MAX1639 evaluation kit, unless otherwise noted.)
LOAD-TRANSIENT RESPONSE
(V_OUT = 2.5V)
A
B
10µs/div
V_IN = 5V, V_OUT = 2.5V, LOAD = 8A
A: V_OUT, 100mV/div, AC COUPLED
B: INDUCTOR CURRENT, 5A/div
FOLDBACK CURRENT LIMIT
(V_OUT = 2.5V, NOMINAL)
A
B
10µs/div
A: V_OUT = 0.5V/div
B: INDUCTOR CURRENT, 5A/div
START-UP WAVEFORMS
A
B
400µs/div
A: INDUCTOR CURRENT, 2A/div
B: V_OUT = 1V/div
SWITCHING WAVEFORMS
A
B
C
0
1µs/div
V_IN = 5V, V_OUT = 2.5V, LOAD = 0A
A: V_OUT, 20mV/div
B: INDUCTOR CURRENT, 2A/div
C: LX, 5V/div
EFFICIENCY vs. OUTPUT CURRENT
100
3.5V
90
2.5V
80
1.8V
70
60
50
0.1
1
10
OUTPUT CURRENT (A)
100
95
90
85
80
75
70
65
60
55
50
0
MAXIMUM DUTY CYCLE vs.
SWITCHING FREQUENCY
200 400 600 800 1000 1200
SWITCHING FREQUENCY (kHz)
4 _______________________________________________________________________________________