Rainbow Electronics MAX1855 - Manual (Page 6)

MAX1716/MAX1854/MAX1855
High-Speed, Adjustable, Synchronous Step-Down
Controllers with Integrated Voltage Positioning
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Note 2: Output voltage accuracy specifications apply to DAC voltages from 0.6V to 2.0V. Includes load-regulation error.
Note 3: When the inductor is in continuous conduction, the output voltage will have a DC regulation level higher than the error-com-
parator threshold by 50% of the ripple. In discontinuous conduction (SKIP = GND, light load), the output voltage will have a
DC regulation level higher than the trip level by approximately 1.5% due to slope compensation.
Note 4: On-time and off-time specifications are measured from 50% to 50% at the DH pin, with LX forced to 0, BST forced to 5V, and
a 500pF capacitor from DH to LX to simulate external MOSFET gate capacitance. Actual in-circuit times may be different
due to MOSFET switching speeds.
Note 5: The MAX1854 does not have overvoltage protection.
Note 6: Specifications to -40°C are guaranteed by design, not production tested.
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, V+ = +15V, V CC = V DD = 5V, SKIP = V CC , VPS = PGND, T A = -40°C to +85°C, unless otherwise noted.) (Note 6)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Current-Limit Threshold
(Positive, Default)
V
ITH
V
PGND
- V
CS
, ILIM = V
CC
100 140 mV
V ILIM = 0.5V 35 65 Current-Limit Threshold
(Positive, Adjustable)
V ITH V PGND - V CS
V ILIM = 2V (REF) 160 240
mV
V CC Undervoltage Lockout
Threshold
Rising edge, hysteresis = 20mV, switching
disabled below this level
4.0 4.45 V
VGATE Lower Trip Threshold
Measured at FB with respect to unloaded
output voltage, falling edge
-12.5 -7.5 %
VGATE Upper Trip Threshold
Measured at FB with respect to unloaded
output voltage, rising edge
7.5 12.5 %
VGATE Output Low Voltage I SINK = 1mA 0.4 V
VGATE Leakage Current High state, forced to 5.5V 1 µA
GATE DRIVERS
DH Gate Driver On-Resistance R ON ( D H ) V BST - V LX forced to 5V 5 Ω
High state (pullup) 5
DL Gate Driver On-Resistance R ON(DL)
Low state (pulldown) 1.7
Ω
LOGIC AND I/O
Logic Input High Voltage V IH D0 −D4, SHDN, SKIP 2.4 V
Logic Input Low Voltage V
IL
D0 −D4, SHDN, SKIP 0.8 V
TON = V CC (200kHz operation) V CC - 0.4
TON = open (300kHz operation) 3.15 3.85
TON = REF (400kHz operation) 1.65 2.35
TON Input Levels
TON = GND (550kHz operation) 0.5
V
TON = GND or V CC -3 3
Logic Input Current
SHDN, SKIP = GND or V
CC -1 1
µA
D0 −D4 Pullup Current D0 −D4 = GND 3 10 µA