Typical operating characteristics – Rainbow Electronics MAX1639 User Manual
Page 4
MAX1639
High-Speed Step-Down Controller with
Synchronous Rectification for CPU Power
4
_______________________________________________________________________________________
FOLDBACK CURRENT LIMIT
(V
OUT
= 2.5V, NOMINAL)
MAX1639-02
A: V
OUT
= 0.5V/div
B: INDUCTOR CURRENT, 5A/div
A
B
10
µ
s/div
START-UP WAVEFORMS
MAX1639-03
A: INDUCTOR CURRENT, 2A/div
B: V
OUT
= 1V/div
A
B
400
µ
s/div
1
µ
s/div
SWITCHING WAVEFORMS
C
0
MAX1639-04
V
IN
= 5V, V
OUT
= 2.5V, LOAD = 0A
A: V
OUT
, 20mV/div
B: INDUCTOR CURRENT, 2A/div
C: LX, 5V/div
B
A
LOAD-TRANSIENT RESPONSE
(V
OUT
= 2.5V)
MAX1639-01
V
IN
= 5V, V
OUT
= 2.5V, LOAD = 8A
A: V
OUT
, 100mV/div, AC COUPLED
B: INDUCTOR CURRENT, 5A/div
A
B
10
µ
s/div
__________________________________________Typical Operating Characteristics
(T
A
= +25°C, using the MAX1639 evaluation kit, unless otherwise noted.)
100
50
0.1
10
EFFICIENCY vs. OUTPUT CURRENT
60
90
80
70
MAX1639-05
OUTPUT CURRENT (A)
EFFICIENCY (%)
1
3.5V
1.8V
2.5V
50
55
0
MAXIMUM DUTY CYCLE vs.
SWITCHING FREQUENCY
65
60
70
MAX1639-06
SWITCHING FREQUENCY (kHz)
MAXIMUM DUTY CYCLE (%)
85
95
90
75
80
200
800
1000
1200
100
600
400