Datasheet

MAX1809
3A, 1MHz, DDR Memory Termination Supply
4 _______________________________________________________________________________________
50
65
60
55
70
75
80
85
90
95
100
EFFICIENCY vs. OUTPUT CURRENT
(SOURCING)
MAX1809 toc01
OUTPUT CURRENT (A)
EFFICIENCY (%)
0321
R
DROOP
= 0Ω
V
IN
= 5V,
V
OUT
= 2.5V
V
IN
= 3.3V,
V
OUT
= 1.25V
V
IN
= 5V,
V
OUT
= 1.25V
EFFICIENCY vs. OUTPUT CURRENT
(SINKING)
MAX1809 toc02
OUTPUT CURRENT (A)
EFFICIENCY (%)
0321
50
60
55
75
70
65
90
85
80
95
R
DROOP
= 0Ω
V
IN
= 5V,
V
OUT
= 1.25V
V
IN
= 5V,
V
OUT
= 2.5V
V
IN
= 3.3V,
V
OUT
= 1.25V
-2.2
-2.6
-3.0
-1.8
-1.4
-0.6
-1.0
-0.2
-3-2-10123
NORMALIZED OUTPUT ERROR
vs. OUTPUT CURRENT
MAX1809 toc03
OUTPUT CURRENT (A)
NORMALIZED OUTPUT ERROR (%)
V
IN
= 3.3V
V
IN
= 5V
4
0
12
8
20
16
24
0231 456
NO-LOAD
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX1809 toc04
V
IN
(V)
NO-LOAD SUPPLY CURRENT (I
IN
+ I
CC
(mA))
0
1.0
0.5
2.0
1.5
3.0
2.5
3.5
4.5
4.0
5.0
0 100 150 20050 250 300 350 450400 500
OFF-TIME vs. R
TOFF
MAX1809 toc05
R
TOFF
(kΩ)
t
OFF
(µs)
0
400
200
800
600
1000
1200
SWITCHING FREQUENCY
vs. OUTPUT CURRENT
MAX1809 toc06
OUTPUT CURRENT (A)
FREQUECNY (kHz)
-3 -1-2 0123
V
IN
= 5V
V
IN
= 3.3V
STARTUP AND SHUTDOWN
MAX1809 toc07
0A
0V
0V
0V
1A/div
V
OUT
1V/div
V
SHDN
5V/div
I
IN
1ms/div
V
SS
2V/div
V
IN
= 3.3V, R
OUT
= 0.5Ω
LOAD-TRANSIENT RESPONSE
MAX1809 toc08
0A
0V
50mV/div
I
OUT
5A/div
V(LX)
5V/div
V
OUT
(AC-COUPLED)
10µs/div
V
EXTREF
= 1.25V, V
IN
= 3.3V, I
OUT
= -2A to +2A to -2A
R
DROOP
= 0Ω
Typical Operating Characteristics
(Circuit of Figure 1, V
OUT
= 1.25V, for V
IN
= 5V: L = 1µH, R
TOFF
= 130kΩ; for V
IN
= 3.3V: L = 0.68µH, R
TOFF
= 73.2kΩ.)