User Manual

MAX1540/MAX1541
Dual Step-Down Controllers with Saturation
Protection, Dynamic Output, and Linear Regulator
6 _______________________________________________________________________________________
Dual Mode is a trademark of Maxim Integrated Products, Inc.
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Valley Current-Limit Threshold
(Fixed)
V
LIM
_
(
VAL
)
V
CSP
_ - V
CSN
_, ILIM_ = V
CC
45 50 55 mV
V
ILIM
_ = 250mV 15 25 35
Valley Current-Limit Threshold
(Adjustable)
V
LIM
_
(
VAL
)
V
CSP
_ - V
CSN
_
V
ILIM
_ = 2.00V 170 200 230
mV
Current-Limit Threshold
(Negative)
V
NEG
V
CSP
_ - V
CSN
_, SKIP = ILIM_ = V
CC
,
T
A
= +25°C
-90 -65 -45 mV
Current-Limit Threshold
(Zero Crossing)
V
ZX
With respect to valley current-limit
threshold, V
CSP
_ - V
CSN
_, SKIP = GND,
ILIM_ = V
CC
2.5 mV
LSAT = V
CC
180 200 220
LSAT = open 157 175 193
Inductor-Saturation Current-Limit
Threshold
With respect to
valley current-
limit threshold,
ILIM_ = V
CC
LSAT = REF 135 150 165
%
ILIM_ Saturation Fault Sink
Current
I
ILIM
_
(
LSAT
)
V
CSP
- V
CSN
> inductor saturation current
limit, 0.25V < V
ILIM
_ < 2.0V
468µA
ILIM_ Leakage Current
V
CSP
_ - V
CSN
_ < inductor saturation current
limit
0.1 µA
GATE DRIVERS
DH_ Gate-Driver On-Resistance R
DH
BST_-LX_ forced to 5V 1.5 5 Ω
DL_, high state 1.5 5
DL_ Gate-Driver On-Resistance R
DL
DL_, low state 0.6 3
Ω
DH_ Gate-Driver Source/Sink
Current
I
DH
DH_ forced to 2.5V, BST_-LX_ forced to 5V 1 A
DL_ Gate-Driver Source Current
I
DL
(
SOURCE
)
DL_ forced to 2.5V 1 A
DL_ Gate-Driver Sink Current I
DL
(
SINK
)
DL_ forced to 2.5V 3 A
DL_ rising 35
Dead Time t
DEAD
DH_ rising 26
ns
INPUTS AND OUTPUTS
OD On-Resistance R
OD
GATE = V
CC
10 25 Ω
OD Leakage Current GATE = GND, OD forced to 5.5V 1 200 nA
Logic Input Threshold
ON1, ON2, SKIP, GATE rising edge,
hysteresis = 225mV
1.2 1.7 2.2 V
LDOON Input Trip Level Rising edge, hysteresis = 250mV 1.20 1.25 1.30 V
Logic Input Current ON1, ON2, LDOON, SKIP, GATE -1 +1 µA
High 1.9 2.0 2.1
Dual Mode™ Threshold Voltage
FB1 (MAX1540),
FB2 (MAX1540/
MAX1541)
Low 0.05 0.1 0.15
V
ELECTRICAL CHARACTERISTICS (continued)
(V+ = 15V, V
CC
= V
DD
= ON1 = ON2 = 5V, SKIP = GND, T
A
= 0°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.)