Datasheet

MAX1638
High-Speed Step-Down Controller with
Synchronous Rectification for CPU Power
_______________________________________________________________________________________ 5
FOLDBACK CURRENT LIMIT
MAX1638-04
V
O
= 2.0V NOMINAL
A: V
OUT
= 0.5V/div
B: INDUCTOR CURRENT, 5A/div
A
B
10μs/div
STARTUP WAVEFORMS
MAX1638-05
A: V
OUT
= 0.5V/div
B: INDUCTOR CURRENT, 5A/div
A
B
400μs/div
1μs/div
SWITCHING WAVEFORMS
C
0
MAX1638-06
V
IN
= 5V, V
OUT
= 2.5V, LOAD = 5A
A: LX, 5V/div C: INDUCTOR CURRENT,
B: V
OUT
, 20mV/div, AC COUPLED 5A/div
B
A
LOAD-TRANSIENT RESPONSE
WITHOUT GLITCHCATCHER (C
OUT
= 880μF)
MAX1638-01
V
IN
= 5V, V
OUT
= 2.0V, LOAD = 14A, 3A/μs
A: V
OUT
, 50mV/div, AC COUPLED
B: INDUCTOR CURRENT, 10A/div
A
B
10μs/div
LOAD-TRANSIENT RESPONSE
WITHOUT GLITCHCATCHER (C
OUT
= 440μF)
MAX1638-02
V
IN
= 5V, V
OUT
= 2.0V, LOAD = 14A, 3A/μs
A: V
OUT
, 100mV/div, AC COUPLED
B: INDUCTOR CURRENT, 10A/div
A
B
10μs/div
LOAD-TRANSIENT RESPONSE
WITH GLITCHCATCHER
MAX1638-03
C
OUT
= 440μF, V
IN
= 5V, V
OUT
= 2.0V, LOAD = 14A, 30A/μs
A: V
OUT
, 100mV/div, C: NDRV, 5V/div
AC COUPLED D: INDUCTOR CURRENT,
B: PDRV, 5V/div 10A/div
A
D
B
C
10μs/div
__________________________________________Typical Operating Characteristics
(T
A
= +25°C, using the MAX1638 evaluation kit, unless otherwise noted.)
100
90
30
0.1 10 100
EFFICIENCY vs. OUTPUT CURRENT
50
40
80
70
60
MAX1638-07
OUTPUT CURRENT (A)
EFFICIENCY (%)
1
V
OUT
= 2.0V
V
OUT
= 1.3V
V
OUT
= 3.5V
5.094
1.094
0.001 0.1 10.01 10
REFERENCE VOLTAGE
vs. OUTPUT CURRENT
1.594
2.094
MAX1638-08
OUTPUT CURRENT (mA)
REFERENCE VOLTAGE (V)
2.594
3.594
3.094
4.094
4.594
SOURCING
CURRENT
SINKING
CURRENT
50
55
0
MAXIMUM DUTY CYCLE
vs. SWITCHING FREQUENCY
65
60
70
MAX1638-09
SWITCHING FREQUENCY (kHz)
MAXIMUM DUTY CYCLE (%)
85
95
90
75
80
200 800 1000 1200
100
600400