Datasheet

Note 1: On Time and Off Time specifications are measured from 50% point to 50% point at the DH pin with LX forced to 0V, BST
forced to 5V, and a 250pF capacitor connected from DH to LX. Actual in-circuit times may differ due to MOSFET switching
speeds.
Note 2: Specifications to -40°C are guaranteed by design and are not production tested.
MAX1917
Tracking, Sinking and Sourcing, Synchronous Buck
Controller for DDR Memory and Termination Supplies
6 _______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (continued)
(V+ = 12V, V
EN/HSD
= V
DDR
= 2.5V, C
VL
= 4.7µF, C
VTTR
= 1µF, C
REF
= 0.22µF, V
FSEL
= 0, ILIM = VL, PGND = LX = POK = GND,
BST = VL. Specifications are for T
A
= -40°C to +85°C, unless otherwise specified.) (Note 2)
PARAMETER CONDITIONS MIN TYP MAX UNITS
Upper VTTR Threshold 110 114
%V
DDR
/2
Lower VTTR Threshold 86 90
%V
DDR
/2
POK Output Low Level I
SINK
= 2mA 0.4 V
POK Output High Leakage V
POK
= 5.5V 5 µA
100
50
0.1 1.0 10.0
EFFICIENCY vs. LOAD CURRENT
AT 1.25V OUTPUT
60
55
MAX1917 toc01
LOAD CURRENT (A)
EFFICIENCY (%)
70
65
80
85
75
90
95
V
IN
= 5V
V
IN
= 2V
V
IN
= 2.5V
CIRCUIT OF FIGURE 3
96
76
0.1 1.0 10.0
EFFICIENCY vs. LOAD CURRENT
AT 0.9V OUTPUT
80
78
MAX1917 toc02
LOAD CURRENT (A)
EFFICIENCY (%)
84
82
88
90
86
92
94
V
IN
= 5V
V
IN
= 2.5V
CIRCUIT OF FIGURE 3
100
0
0.1 1.0 10.0
EFFICIENCY vs. LOAD CURRENT
AT 1.25V OUTPUT
20
10
MAX1917 toc03
LOAD CURRENT (A)
EFFICIENCY (%)
40
30
60
70
50
80
90
V
IN
= 12V
V
IN
= 2.5V
CIRCUIT OF FIGURE 4
V
IN
= 5V
95
0.1 1.0 10.0
EFFICIENCY vs. LOAD CURRENT
AT 0.9V OUTPUT
55
50
MAX1917 toc04
LOAD CURRENT (A)
EFFICIENCY (%)
65
60
75
80
70
85
90
CIRCUIT OF FIGURE 4
V
IN
= 5V
V
IN
= 2.5V
300
350
450
400
550
600
500
650
-8 -4 -2-6 02468
FREQUENCY vs. LOAD CURRENT
AT 1.25V OUTPUT
MAX1917 toc05
LOAD CURRENT (A)
FREQUENCY (kHz)
V
IN
= 12V
CIRCUIT OF FIGURE 3
V
IN
= 5V
V
IN
= 2.5V
300
450
400
350
600
550
500
650
-8 -2 0-6-4 2468
FREQUENCY vs. LOAD CURRENT
AT 0.9V OUTPUT
MAX1917 toc06
LOAD CURRENT (A)
FREQUENCY (kHz)
CIRCUIT OF FIGURE 3
V
IN
= 5V
V
IN
= 2.5V
Typical Operating Characteristics
(V+ = 12V, V
OUT
= 1.25V, T
A
= +25°C, unless otherwise noted.)