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MAX1970EEE+

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21
General Description
The MAX1970/MAX1971/MAX1972 dual-output current-
mode PWM buck regulators operate from 2.6V to 5.5V
input and deliver a minimum of 750mA on each output.
The MAX1970 and MAX1972 operate at a fixed 1.4MHz
(MAX1971 operates at 700kHz) to reduce output induc-
tor and capacitor size and cost. Switching the regula-
tors 180° out-of-phase also reduces the input capacitor
size and cost. Ceramic capacitors can be used for
input and output.
The output voltages are programmable from 1.2V to V
IN
using external feedback resistors, or can be preset to
1.8V or 3.3V for output 1 and 1.5V or 2.5V for output 2.
When one output is higher than 1.2V, the second can
be configured down to sub-1V levels. Output accuracy
is better than ±1% over variations in load, line, and tem-
perature. Internal soft-start reduces inrush current dur-
ing startup.
All devices feature power-on reset (POR). The
MAX1971 includes a reset input (RSI), which forces
POR low for 175ms after RSI goes low. The MAX1970
and MAX1972 include an open-drain power-fail output
(PFO) that monitors input voltage and goes high when
the input falls below 3.94V. For USB-powered xDSL
modems, this output can be used to detect USB power
failure. A minimum switching frequency of 1.2MHz
ensures operation outside the xDSL band.
Applications
Features
o Current-Mode, 1.4MHz Fixed-Frequency PWM
Operation
o 180° Out-of-Phase Operation Reduces Input
Capacitor
o ±1% Output Accuracy Over Load, Line, and
Temperature Ranges
o 750mA Guaranteed Output Current
o 2.6V to 5.5V Input
o Power-On Reset Delay of 16.6ms (MAX1970) or
175ms (MAX1971 and MAX1972)
o Power-Fail Output (MAX1970 and MAX1972 Only)
o Power-On Reset Input (MAX1971 Only)
o Operation Outside xDSL Band
o Ultra-Compact Design with Smallest External
Components
o Outputs Adjustable from 0.8V to V
IN
or 1.8V/3.3V
and 1.5V/2.5V Preset
o All-Ceramic Capacitor Application
o Soft-Start Reduces Inrush Current
MAX1970/MAX1971/MAX1972
Dual, 180° Out-of-Phase, 1.4MHz, 750mA Step-
Down Regulator with POR and RSI/PFO
________________________________________________________________
Maxim Integrated Products
1
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
LX1 PGND
LX2
IN
FBSEL1
FBSEL2
PF0 (MAX1970/MAX1972)
RSI (MAX1971)
EN
POR
TOP VIEW
MAX1970
MAX1971
MAX1972
QSOP
V
CC
COMP1
COMP2
FB1
FB2
REF
GND
Pin Configuration
V
CC
V
CC
RSI
EN
COMP1
COMP2
FBSEL1
FBSEL2
REF
POR
POR
OUT1
1.8V
750mA
OUT2
2.5V
750mA
RSI
LX1
FB2
FB1
LX2
PGND
IN
MAX1971
EN
V
IN
2.6V TO 5.5V
Typical Operating Circuit
19-2297; Rev 1; 2/09
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
xDSL Modems
xDSL Routers
Copper Gigabit SFP
and GBIC Modules
USB-Powered Devices
Dual LDO Replacement
Ordering Information
PART TEMP RANGE PIN-PACKAGE
MAX1970EEE -40°C to +85°C 16 QSOP
MAX1971EEE -40°C to +85°C 16 QSOP
MAX1972EEE -40°C to +85°C 16 QSOP
MAX1970/MAX1971/MAX1972
Dual, 180° Out-of-Phase, 1.4MHz, 750mA Step-
Down Regulator with POR and RSI/PFO
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
IN, EN, FBSEL1, FBSEL2, PFO, POR,
RSI, V
CC
to GND ...................................................-0.3V to +6V
COMP1, COMP2, FB1, FB2,
REF to GND.............................................-0.3V to (V
CC
+ 0.3V)
LX1, LX2 to PGND .......................................-0.3V to (V
IN
+ 0.3V)
PGND to GND .......................................................-0.3V to +0.3V
Continuous Power Dissipation (T
A
= +70°C)
16-Pin QSOP (derate 8.3mW/°C above +70°C)...........667mW
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
ELECTRICAL CHARACTERISTICS
(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
IN AND V
CC
IN Voltage Range 2.6 5.5 V
MAX1971 5 10
IN Supply Current
Switching with no load
V
IN
= 3.3V
MAX1970/MAX1972 10 20
mA
MAX1970/MAX1972 1 100
IN Shutdown Current V
IN
= 5.5V, V
EN
= 0
MAX1971 1 60
µA
V
CC
rising 2.40 2.55
V
CC
Undervoltage
Lockout Threshold
V
CC
falling 2.20 2.35
V
REF
REF Voltage I
REF
= 0, V
IN
= 2.6V to 5.5V 1.188 1.200 1.212 V
REF Shutdown Resistance REF to GND, V
EN
= 0 10 25 Ω
REF Soft-Start Current V
REF
= 1V 20 25 30 µA
FB1 AND FB2
FB_ Regulation Voltage
FBSEL_ = unconnected, OUT1 = FB1, OUT2 = FB2,
V
COMP_
= 1.20V to 1.80V, V
IN
= 2.6V to 5.5V
1.188 1.200 1.212 V
OUT_ Voltage Range FBSEL_ = unconnected 1.2 V
IN
V
V
IN
= 2.6V to 5.5V V
COMP1
= 1.2V, FBSEL1= GND 1.782 1.800 1.818
OUT1 Regulation Voltage
V
IN
= 4.5V to 5.5V V
COMP1
= 1.2V, FBSEL1 = V
CC
3.2670 3.3 3.330
V
V
COMP2
= 1.2V, FBSEL2 = GND 1.485 1.5 1.150
OUT2 Regulation Voltage V
IN
= 2.6V to 5.5V
V
COMP2
= 1.2V, FBSEL2 = V
CC
2.475 2.5 2.525
V
Maximum Output Current Guaranteed by design (Note 1) 750 mA
FBSEL1 = GND 30 60 120
FB1 Input Resistance
Measured from FB1 to
GND
FBSEL1 = V
CC
30 60 120
kΩ
FBSEL2 = GND 22.5 45 90
FB2 Input Resistance
Measured from FB2 to
GND
FBSEL2 = V
CC
22.5 45 90
kΩ
FB_ Input Bias Current FB1 or FB2, FBSEL_ = unconnected, V
FB1
= V
FB2
= 1.15V 0.01 0.1 µA
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
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21

MAX1970EEE+

Mfr. #:
Buy MAX1970EEE+
Manufacturer:
Maxim Integrated
Description:
Switching Voltage Regulators Dual 180 Out 1.4MHz 750mA Step-Down
Lifecycle:
New from this manufacturer.
Delivery:
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