Datasheet

MAX1970/MAX1971/MAX1972
Dual, 180° Out-of-Phase, 1.4MHz, 750mA Step-
Down Regulator with POR and RSI/PFO
_______________________________________________________________________________________ 5
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= V
CC
= V
EN
= 5V, V
FB1
= V
FB2
= 1.15V, R
POR
= 100kΩ to IN, R
PFO
= 100kΩ to IN, RSI = 0, C
VCC
= 0.1µF, C
REF
= 0.1µF,
FBSEL1 = unconnected, FBSEL2 = unconnected, T
A
= -40°C to +85°C.) (Note 2)
PARAMETER CONDITIONS MIN TYP MAX UNITS
FBSEL1 = GND 30 120
FB1 Input Resistance
Measured from FB1 to
GND
FBSEL1 = V
CC
30 120
kΩ
FBSEL2 = GND 22.5 90
FB2 Input Resistance
Measured from FB2 to
GND
FBSEL2 = V
CC
22.5 90
kΩ
FB_ Input Bias Current FB1 or FB2, FBSEL_ = unconnected, V
FB1
= V
FB2
= 1.15V 0.1 µA
COMP1 AND COMP2
COMP1
Transconductance
FB1 = COMP1,
V
COMP1
= 1.2V
FBSEL1 = unconnected 35 85 µS
COMP2
Transconductance
FB2 = COMP2,
V
COMP2
= 1.2V
FBSEL2 = unconnected 35 85 µS
LX1 AND LX2
V
IN
= 5.0V 0.32
Internal High-Side
MOSFET On-Resistance
I
LX
= -180mA
V
IN
= 3.3V 0.37
Ω
V
IN
= 5.0V 0.23
Internal Low-Side
MOSFET On-Resistance
I
LX
= 180mA
V
IN
= 3.3V 0.25
Ω
LX_ Current-Sense
Transresistance
0.4 0.6 V/A
High side 0.76 1.60
LX_ Current-Limit
Threshold
Duty cycle = 100%,
V
IN
= 2.6V to 5.5V
Low side -1.6 -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 1.6
LX_ Switching Frequency V
IN
= 2.6V to 5.5V
MAX1971 0.60 0.80
MHz
MAX1970/MAX1972 20
LX_ Minimum Duty Cycle V
IN
= 2.6V to 5.5V
MAX1971 15
%
POR
V
OUT
rising 94
POR Thresholds
Percentage of V
OUT
,
V
IN
= 2.6V to 5.5V
V
OUT
falling 87
%
MAX1970 13.3 20
POR Delay Time (T
D
)
MAX1971/MAX1972 140 210
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
0.05 V
POR Start-Up Voltage FB1 = FB2 = GND, I
POR
= 100µA, V
IN
= 1.2V 0.05 V