Datasheet

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