Datasheet

MAX1970/MAX1971/MAX1972
Dual, 180° Out-of-Phase, 1.4MHz, 750mA Step-
Down Regulator with POR and RSI/PFO
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= V
CC
= V
EN
= 5V, R
POR
= 100kΩ to IN, R
PFO
= 100kΩ to IN, V
RSI
= 0, C
REF
= 0.1µF, FBSEL1 = unconnected, FBSEL2 =
unconnected, T
A
= 0°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER CONDITIONS MIN TYP MAX UNITS
COMP1 AND COMP2
COMP1
Transconductance
FB1 = COMP1,
V
COMP1
= 1.2V
FBSEL1 = unconnected 35 55 85 µS
COMP2
Transconductance
FB2 = COMP2,
V
COMP2
= 1.2V
FBSEL2 = unconnected 35 55 85 µS
LX1 AND LX2
V
IN
= 5.0V 0.20 0.32
V
IN
= 3.3V 0.24 0.37
Internal High-Side
MOSFET On-Resistance
I
LX
= -180mA
V
IN
=2.6V 0.28
Ω
V
IN
= 5.0V 0.12 0.23
V
IN
= 3.3V 0.14 0.25
Internal Low-Side
MOSFET On-Resistance
I
LX
= 180mA
V
IN
= 2.6V 0.16
Ω
LX_ Current-Sense
Transresistance
0.4 0.5 0.6 V/A
High side 0.80 1.2 1.60
LX_ Current-Limit
Threshold
Duty Cycle = 100%,
V
IN
= 2.6V to 5.5V
Low side -1.6 -0.85 -0.40
A
V
LX1
= V
LX2
= 5.5V 20
LX_ Leakage Current V
IN
= 5.5V
V
LX1
= V
LX2
= 0 -20
µA
MAX1970/MAX1972 1.2 1.4 1.6
LX_ Switching Frequency V
IN
= 2.6V to 5.5V
MAX1971 0.60 0.70 0.80
MHz
LX_ Maximum Duty Cycle 100 %
MAX1970/MAX1972 15 20
LX_ Minimum Duty Cycle V
IN
= 2.6V to 5.5V
MAX1971 10 15
%
POR
V
OUT
rising 92 94
POR Thresholds
Percentage of V
OUT
,
V
IN
= 2.6V to 5.5V
V
OUT
falling 87 90
%
MAX1970 13.3 16.6 20
POR Delay Time (T
D
)
MAX1971/MAX1972 140 175 210
ms
POR Output Current, High V
POR
= V
IN
= 5.5V, V
FB1
= V
FB2
= 1.15V -1 1 µA
POR Output Voltage, Low
V
FB1
= 1.05V or V
FB2
= 1.05V or RSI = IN (MAX1971 only),
I
POR
= 1mA
0.01 0.05 V
POR Startup Voltage FB1 = FB2 = GND, I
POR
= 100µA, V
IN
= 1.2V 0.01 0.05 V