Tracking, Sinking and Sourcing, Synchronous Buck
Controller for DDR Memory and Termination Supplies
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
= 0°C to +85°C.
Typical values are at T
A
= +25°C, unless otherwise specified.)
PARAMETER
Thermal Shutdown
SOFT-START
ILIM Ramp Period
OSCILLATOR
FSEL = VL
Oscillator Frequency
FSEL = unconnected
FSEL = REF
FSEL = GND
FSEL = VL
On Time (Note 1)
FSEL not connected
FSEL = REF
FSEL = GND
Minimum Off Time (Note 1)
CURRENT LIMIT
LX to PGND, ILIM = VL
Current-Limit Threshold
(Positive Direction)
Current-Limit Threshold
(Negative Direction)
ILIM Input Current
V
L
REGULATOR
Output Voltage
Line Regulation
RMS Output Current
Bypass Capacitor
DRIVER
DH Gate-Driver On-Resistance
DL Gate-Driver On-Resistance
(Source)
DL Gate-Driver On-Resistance
(Sink)
Dead Time
FSEL LOGIC
Logic Input Current
Logic GND Level
Logic REF Level
Logic Float Level
FSEL = VREF
FSEL floating
1.65
3.15
-3
3
0.5
2.35
3.85
µA
V
V
V
V
BST
- V
LX
= 5V
DL high state
DL low state
DL rising
DL falling
1.4
1.6
0.75
32
30
2.5
3
1.25
Ω
Ω
Ω
ns
ESR < 100mΩ
2.2
5.5V < V+ < 14V
1mA < I
VL
< 35mA
5.5V < V+ < 14V, I
VL
= 10mA
4.8
5.0
0.2
35
5.2
V
%
mA
µF
LX to PGND, R
ILIM
= 100kΩ
LX to PGND, R
ILIM
= 400kΩ
LX to PGND, ILIM = VL, with percentage of positive
current-limit threshold
90
40
170
-90
100
50
200
-110
5
110
60
230
-130
%
µA
mV
2.18
1.45
1.09
0.82
200
300
400
550
2.5
1.67
1.25
0.91
350
2.83
1.89
1.41
1.00
400
ns
µs
kHz
Ramps the ILIM trip threshold from 20% to 100%
in 20% increments
1.7
ms
CONDITIONS
Rising temperature, typical hysteresis = 15°C
MIN
TYP
+160
MAX
UNITS
°C
MAX1917
_______________________________________________________________________________________
3
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
