(PDF) MAX756 Datasheet PDF | Maxim





MAX756 Datasheet PDF

Part Number MAX756
Description 3.3V/5V/Adjustable-Output / Step-Up DC-DC Converters
Manufacture Maxim
Total Page 8 Pages
PDF Download Download MAX756 Datasheet PDF

Features: Datasheet pdf 19-0113; Rev. 2; 1/95 NUAL KIT MA ATION U EET L H A S V A E T WS DA FOLLO 3.3 V/5V/Adjustable-Output, Step-Up DC-DC C onverters ____________________________F eatures o Operates Down to 0.7V Input S upply Voltage o 87% Efficiency at 200mA o 60µA Quiescent Current o 20µA Shut down Mode with Active Reference and LBI Detector o 500kHz Maximum Switching Fr equency o ±1.5% Reference Tolerance Ov er Temperature o Low-Battery Detector ( LBI/LBO) o 8-Pin DIP and SO Packages _ ______________General Description The M AX756/MAX757 are CMOS step-up DC-DC swi tching regulators for small, low input voltage or battery-powered systems. The MAX756 accepts a positive input voltag e down to 0.7V and converts it to a hig her pinselectable output voltage of 3.3 V or 5V. The MAX757 is an adjustable ve rsion that accepts an input voltage dow n to 0.7V and generates a higher adjust able output voltage in the range from 2 .7V to 5.5V. Typical full-load efficien cies for the MAX756/MAX757 are greater than 87%. The MAX756/MAX757.

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MAX756 datasheet
19-0113; Rev. 2; 1/95
EVFAOLLULAOTWIOSNDKAITTAMSAHNEUEATL
3.3V/5V/Adjustable-Output,
Step-Up DC-DC Converters
_______________General Description
The MAX756/MAX757 are CMOS step-up DC-DC switch-
ing regulators for small, low input voltage or battery-pow-
ered systems. The MAX756 accepts a positive input
voltage down to 0.7V and converts it to a higher pin-
selectable output voltage of 3.3V or 5V. The MAX757 is
an adjustable version that accepts an input voltage down
to 0.7V and generates a higher adjustable output voltage
in the range from 2.7V to 5.5V. Typical full-load efficiencies
for the MAX756/MAX757 are greater than 87%.
The MAX756/MAX757 provide three improvements over
previous devices. Physical size is reduced—the high
switching frequencies (up to 0.5MHz) made possible by
MOSFET power transistors allow for tiny (<5mm diameter)
surface-mount magnetics. Efficiency is improved to 87%
(10% better than with low-voltage regulators fabricated in
bipolar technology). Supply current is reduced to 60µA
by CMOS construction and a unique constant-off-time
pulse-frequency modulation control scheme.
________________________Applications
3.3V to 5V Step-Up Conversion
Palmtop Computers
Portable Data-Collection Equipment
Personal Data Communicators/Computers
Medical Instrumentation
2-Cell & 3-Cell Battery-Operated Equipment
Glucose Meters
__________Typical Operating Circuit
____________________________Features
o Operates Down to 0.7V Input Supply Voltage
o 87% Efficiency at 200mA
o 60µA Quiescent Current
o 20µA Shutdown Mode with Active Reference and
LBI Detector
o 500kHz Maximum Switching Frequency
o ±1.5% Reference Tolerance Over Temperature
o Low-Battery Detector (LBI/LBO)
o 8-Pin DIP and SO Packages
______________Ordering Information
PART
MAX756CPA
MAX756CSA
MAX756C/D
MAX756EPA
MAX756ESA
MAX757CPA
MAX757CSA
MAX757C/D
MAX757EPA
MAX757ESA
TEMP. RANGE
0°C to +70°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
8 Plastic DIP
8 SO
Dice*
8 Plastic DIP
8 SO
8 Plastic DIP
8 SO
Dice*
8 Plastic DIP
8 SO
* Dice are tested at TA = +25°C only.
_________________Pin Configurations
INPUT
2V to VOUT
1
SHDN
150µF
5
LBI
8
LX
2
3/5
MAX756
6
OUT
OUTPUT
22µH
5V at 200mA
or
1N5817 3.3V at 300mA
100µF
0.1µF
3
REF
4
LBO
GND
7
LOW-BATTERY
DETECTOR OUTPUT
TOP VIEW
SHDN 1
3/5 2
REF 3
LBO 4
MAX756
DIP/SO
8 LX
7 GND
6 OUT
5 LBI
SHDN 1
FB 2
REF 3
LBO 4
MAX757
DIP/SO
8 LX
7 GND
6 OUT
5 LBI
________________________________________________________________ Maxim Integrated Products 1
Call toll free 1-800-998-8800 for free samples or literature.

MAX756 datasheet
3.3V/5V/Adjustable-Output,
Step-Up DC-DC Converters
ABSOLUTE MAXIMUM RATINGS
Supply Voltage (OUT to GND) ....................................-0.3V, +7V
Switch Voltage (LX to GND) ........................................-0.3V, +7V
Auxiliary Pin Voltages (SHDN, LBI, LBO, REF,
3/5, FB to GND) ........................................-0.3V, (VOUT + 0.3V)
Reference Current (IREF) ....................................................2.5mA
Continuous Power Dissipation (TA = +70°C)
Plastic DIP (derate 9.09mW/°C above +70°C) .............727mW
SO (derate 5.88mW/°C above +70°C) ..........................471mW
Operating Temperature Ranges:
MAX75_C_ _ ........................................................0°C to +70°C
MAX75_E_ _......................................................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range............................... -65°to +160°C
Lead Temperature (soldering, 10sec) ........................... +300°C
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.
ELECTRICAL CHARACTERISTICS
(Circuits of Figure 1 and Typical Operating Circuit, VIN = 2.5V, ILOAD = 0mA, TA = TMIN to TMAX, unless otherwise noted.)
PARAMETER
Output Voltage
Minimum Start-Up Supply Voltage
CONDITIONS
MAX756, 3/5 = 0V, 0mA < ILOAD < 200mA
2V < VIN < 3V MAX756, 3/5 = 3V, 0mA < ILOAD < 300mA
MAX757, VOUT = 5V, 0mA < ILOAD < 200mA
ILOAD = 10mA
Minimum Operating Supply
Voltage (once started)
ILOAD = 20mA
MIN
4.8
3.17
4.8
TYP
5.0
3.30
5.0
1.1
0.7
MAX
5.2
3.43
5.2
1.8
Quiescent Supply Current in
3.3V Mode (Note 1)
ILOAD = 0mA, 3/5 = 3V, LBI = 1.25V, VOUT = 3.47V,
FB = 1.3V (MAX757 only)
60
UNITS
V
V
V
µA
Battery Quiescent Current
Measured at VIN in Figure 1
Output set for 3.3V
Shutdown Quiescent Current
(Note 1)
SHDN = 0V, LBI = 1.25V, 3/5 = 3V, VOUT = 3.47V,
FB = 1.3V (MAX757 only)
Reference Voltage
Reference-Voltage Regulation
LBI Input Threshold
No REF load, CREF = 0.1µF
3/5 = 3V, -20µA < REF load < 250µA, CREF = 0.22µF
With falling edge
LBI Input Hysteresis
LBO Output Voltage Low
LBO Output Leakage Current
ISINK = 2mA
LBO = 5V
SHDN, 3/5 Input Voltage Low
SHDN, 3/5 Input Voltage High
SHDN, 3/5, FB, LBI Input Current
LBI = 1.25V, FB = 1.25V, SHDN = 0V or 3V,
3/5 = 0V or 3V
FB Voltage
MAX757
Output Voltage Range
MAX757, ILOAD = 0mA (Note 2)
60 µA
1.23
1.22
1.6
1.22
2.7
20
1.25
0.8
1.25
25
40
1.27
2.0
1.28
0.4
1
0.4
1.25
±100
1.28
5.5
µA
V
%
V
mV
V
µA
V
V
nA
V
V
Note 1: Supply current from the 3.3V output is measured with an ammeter between the 3.3V output and OUT pin. This current
correlates directly with actual battery supply current, but is reduced in value according to the step-up ratio and efficiency.
Note 2: Minimum value is production tested. Maximum value is guaranteed by design and is not production tested.
2 _______________________________________________________________________________________




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