MAX772CSA ,5V/12V/15V or Adjustable, High-Efficiency, Low IQ, Step-Up DC-DC ControllersMAX770–MAX77319-0202; Rev 2; 11/965V/12V/15V or Adjustable, High-Efficiency, Low I , Step-Up DC-DC ..
MAX772CSA ,5V/12V/15V or Adjustable, High-Efficiency, Low IQ, Step-Up DC-DC ControllersApplicationsOrdering Information continued at end of data sheet.Positive LCD-Bias Generators*Contac ..
MAX772CSA ,5V/12V/15V or Adjustable, High-Efficiency, Low IQ, Step-Up DC-DC ControllersMAX770–MAX77319-0202; Rev 2; 11/965V/12V/15V or Adjustable, High-Efficiency, Low I , Step-Up DC-DC ..
MAX772CSA+ ,5V/12V/15V or Adjustable, High-Efficiency Low-IQ, Step-Up DC-DC ControllersGeneral Description ________
MAX772ESA ,5V/12V/15V or Adjustable, High-Efficiency, Low IQ, Step-Up DC-DC ControllersELECTRICAL CHARACTERISTICS(V+ = 5V, I = 0mA, T = T to T , unless otherwise noted. Typical values ar ..
MAX772ESA ,5V/12V/15V or Adjustable, High-Efficiency, Low IQ, Step-Up DC-DC ControllersApplicationsMAX770C/D 0°C to +70°C Dice* Palmtops/Handy-TerminalsMAX770EPA -40°C to +85°C 8 Plastic ..
MB6M ,MINIATURE GLASS PASSIVATED SINGLE-PHASE BRIDGE RECTIFIERThermal Characteristics (TA = 25°C unless otherwise noted)Parameter Symbol MB2M MB4M MB6M UnitDevic ..
MB6S ,Bridge RectifiersThermal Characteristics (T = 25°C unless otherwise noted)AParameter Symbol MB2S MB4S MB6S UnitDevic ..
MB7117E , Schottky TTL 2048-Bit Bipolar Programmable Read-Only Memory
MB71A38-25 , PROGRAMMABLE SCHOTTKY 16384-BIT READ ONLY MEMORY
MB8117800A-60 ,2 M X 8 BIT FAST PAGE MODE DYNAMIC RAMapplications where very low power dissipation and high bandwidth are basic requirements of the desi ..
MAX770CPA-MAX770CSA-MAX770EPA-MAX770ESA-MAX771CSA-MAX771ESA-MAX771MJA-MAX772CPA-MAX772CSA-MAX772ESA-MAX773CSD-MAX773ESD
5V/12V/15V or Adjustable, High-Efficiency, Low IQ, Step-Up DC-DC Controllers
_______________General DescriptionThe MAX770–MAX773 step-up switching controllers pro-
vide 90% efficiency over a 10mA to 1A load. A
unique current-limited pulse-frequency-modulation (PFM)
control scheme gives these devices the benefits of
pulse-width-modulation (PWM) converters (high efficiency
at heavy loads), while using less than 110µA of supply
current (vs. 2mA to 10mA for PWM converters).
These ICs use tiny external components. Their high
switching frequencies (up to 300kHz) allow surface-
mount magnetics of 5mm height and 9mm diameter.
The MAX770/MAX771/MAX772 accept input voltages
from 2V to 16.5V. Output voltages are preset at 5V,
(MAX770), 12V (MAX771), and 15V (MAX772); they can
also be adjusted using two resistors.
The MAX773 accepts inputs from 3V to 16.5V. For a wider
input range, it features an internal shunt regulator that
allows unlimited higher input voltages. The MAX773’s out-
put can be set to 5V, 12V, or 15V, or it can be adjusted
with two resistors.
The MAX770–MAX773 drive external N-channel MOSFET
switches, allowing them to power loads up to 15W. If less
power is required, use the MAX756/MAX757 or
MAX761/MAX762 step-up switching regulators with on-
board MOSFETs.
________________________ApplicationsPalmtops/Handy-Terminals
High-Efficiency DC-DC Converters
Battery-Powered Applications
Positive LCD-Bias Generators
Portable Communicators
Flash Memory Programmers
____________________________Features90% Efficiency for 10mA to 1A Load CurrentsUp to 15W Output Power110µA Max Supply Current5µA Max Shutdown Current2V to 16.5V Input Range
(MAX770/MAX771/MAX772)Internal Shunt Regulator for High Input Voltages
(MAX773)Preset or Adjustable Output Voltages
MAX770: 5V or Adjustable
MAX771: 12V or Adjustable
MAX772: 15V or Adjustable
MAX773: 5V, 12V, 15V, or AdjustableCurrent-Limited PFM Control Scheme300kHz Switching Frequency
______________Ordering Information
Ordering Information continued at end of data sheet.*Contact factory for dice specifications.
**Contact factory for availability and processing to MIL-STD-883B.
MAX770–MAX773
5V/12V/15V or Adjustable, High-Efficiency,
Low IQ, Step-Up DC-DC Controllers
_________________Pin Configurations
__________Typical Operating Circuit
MAX770–MAX773
5V/12V/15V or Adjustable, High-Efficiency,
Low IQ, Step-Up DC-DC Controllers
ABSOLUTE MAXIMUM RATINGSSupply Voltages
V+ to GND.............................................................-0.3V to 17V
V+ to SGND.............................................................-0.3V to 7V
SGND........................................................-0.3V to (V+ + 0.3V)
EXT, CS, REF, LBO, LBI, SHDN, FB.............-0.3V to (V+ + 0.3V)
EXTH, EXTL..................................................-0.3V to (V+ + 0.3V)
V5, V12, V15.............................................................-0.3V to 17V
GND to AGND.........................................................0.1V to -0.1V
ISGND..................................................................................50mA
Continuous Power Dissipation (TA= +70°C)
8-Pin Plastic DIP (derate 9.09mW/°C above +70°C)....727mW
8-Pin SO (derate 5.88mW/°C above +70°C)................471mW
8-Pin CERDIP (derate 8.00mW/°C above +70°C)........640mW
14-Pin Plastic DIP
(derate 10.00mW/°C above +70°C).............................800mW
14-Pin SO (derate 8.33mW/°C above +70°C)..............667mW
14-Pin CERDIP (derate9.09mW/°C above +70°C)......727mW
Operating Temperature Ranges
MAX77_C__........................................................0°C to +70°C
MAX77_E__......................................................-40°C to +85°C
MAX77_MJ_...................................................-55°C to +125°C
Junction Temperatures
MAX77_C__/E__..........................................................+150°C
MAX77_MJ_..................................................................+175°C
Storage Temperature Range.............................-65°C 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(V+ = 5V, ILOAD= 0mA, TA= TMINto TMAX, unless otherwise noted. Typical values are at TA= +25°C.)
MAX770–MAX773
5V/12V/15V or Adjustable, High-Efficiency,
Low IQ, Step-Up DC-DC Controllers
ELECTRICAL CHARACTERISTICS (continued)(V+ = 5V, ILOAD= 0mA, TA= TMINto TMAX, unless otherwise noted. Typical values are at TA= +25°C.)
Note 1:Output voltage guaranteed using preset voltages. See Figures 7a–7d for output current capability versus input voltage.
Note 2:Output voltage line and load regulation depend on external circuit components.
Note 3:For the MAX773, EXT is EXTH and EXTL shorted together.
MAX770–MAX773
5V/12V/15V or Adjustable, High-Efficiency,
Low IQ, Step-Up DC-DC Controllers
__________________________________________Typical Operating Characteristics(TA = +25°C, unless otherwise noted.)
MAX770–MAX773
5V/12V/15V or Adjustable, High-Efficiency,
Low IQ, Step-Up DC-DC Controllers
____________________________Typical Operating Characteristics (continued)(TA = +25°C, unless otherwise noted.)
MAX770–MAX773
5V/12V/15V or Adjustable, High-Efficiency,
Low IQ, Step-Up DC-DC Controllers
____________________________Typical Operating Characteristics (continued)(Circuit of Figure 2a, TA = +25°C, unless otherwise noted.)
MAX770–MAX773
5V/12V/15V or Adjustable, High-Efficiency,
Low IQ, Step-Up DC-DC Controllers
______________________________________________________________Pin Description
____________________________Typical Operating Characteristics (continued)(Circuit of Figure 2a, TA = +25°C, unless otherwise noted.)
MAX770–MAX773
5V/12V/15V or Adjustable, High-Efficiency,
Low IQ, Step-Up DC-DC Controllers
_______________Detailed DescriptionThe MAX770–MAX773 are BiCMOS, step-up, switch-
mode power-supply controllers that provide preset 5V,
12V, and 15V output voltages, in addition to adjustable-
output operation. Their unique control scheme com-
bines the advantages of pulse-frequency modulation
(low supply current) and pulse-width modulation (high
efficiency with heavy loads), providing high efficiency
over a wide output current range, as well as increased
output current capability over previous PFM devices.
In addition, the external sense resistor and power
transistor allow the user to tailor the output current
capability for each application. Figure 1 shows the
MAX770–MAX773 block diagram.
The MAX770–MAX773 offer three main improvements
over prior pulse-skipping control solutions: 1) the con-
verters operate with tiny (5mm height and less than
9mm diameter) surface-mount inductors due to their
300kHz switching frequency; 2) the current-limited PFM
control scheme allows 87% efficiencies over a wide
range of load currents; and 3) the maximum supply
current is only 110µA.
The MAX773 can be configured to operate from an
internal 6V shunt regulator, allowing very high input/out-
put voltages. Its output can be configured for an
adjustable voltage or for one of three fixed voltages
(5V, 12V, or 15V), and it has a power-fail comparator for
low-battery detection.
All devices have shutdown capability, reducing the
supply current to 5µA max.
Bootstrapped/Non-Bootstrapped ModesFigures 2 and 3 show standard application circuits for
bootstrapped and non-bootstrapped modes. In boot-
strapped mode, the IC is powered from the output
(VOUT, which is connected to V+) and the input voltage
range is 2V to VOUT. The voltage applied to the gate of
the external power transistor is switched from VOUTto
ground, providing more switch gate drive and thus
reducing the transistor’s on resistance.
In non-bootstrapped mode, the IC is powered from the
input voltage (V+) and operates with minimum supply
current. In this mode, FB is the output voltage sense
point. Since the voltage swing applied to the gate of the
external power transistor is reduced (the gate swings
from V+ to ground), the power transistor’s on resistance
increases at low input voltages. However, the supply
current is also reduced because V+ is at a lower volt-
age, and because less energy is consumed while
charging and discharging the external MOSFET’s gate
capacitance. The minimum input voltage for the
MAX770–MAX773 is 3V when using external feedback
resistors. With supply voltages below 5V, bootstrapped
mode is recommended.
Note: When using the MAX770/MAX771/MAX772 in
non-bootstrapped mode, there is no preset output
operation because V+ is also the output voltage
sense point for fixed-output operation. External
resistors must be used to set the output voltage.Use 1% external feedback resistors when operating
in adjustable-output mode (Figures 2c, 2d, 3b, 3d, 3e)
to achieve an overall output voltage accuracy of ±5%.
The MAX773 can be operated in non-bootstrapped
mode without using external feedback resistors
because V+ does not act as the output voltage sense
point with preset-output operation. To achieve high-
est efficiency, operate in bootstrapped mode when-
ever possible.
MAX773 Shunt-Regulator OperationThe MAX773 has an internal 6V shunt regulator that
allows the device to step up from very high input
voltages (Figure 4).
Floating the shunt-regulator ground (SGND) disables
the shunt regulator. To enable it, connect SGND to
GND. The shunt regulator requires 1mA minimum cur-
rent for proper operation; the maximum current must
not exceed 20mA. The MAX773 operates in non-boot-
strapped mode when the shunt regulator is used, and
EXT swings between the 6V shunt-regulator voltage
and GND.
When using the shunt regulator, use an N-channel pow-
er FET instead of an NPN power transistor as the power
switch. Otherwise, excessive base drive will collapse
the shunt regulator.
External Power-Transistor
Control Circuitry
PFM Control SchemeThe MAX770–MAX773 use a proprietary current-limited
PFM control scheme to provide high efficiency over a
wide range of load currents. This control scheme com-
bines the ultra-low supply current of PFM converters (or
pulse skippers) with the high full-load efficiency of
PWM converters.
Unlike traditional PFM converters, the MAX770–
MAX773 use a sense resistor to control the peak induc-
tor current. They also operate with high switching
MAX770–MAX773
5V/12V/15V or Adjustable, High-Efficiency,
Low IQ, Step-Up DC-DC Controllers
MAX770–MAX773frequencies (up to 300kHz), allowing the use of tiny
external components.
As with traditional PFM converters, the power transistor
is not turned on until the voltage comparator senses
that the output is out of regulation. However, unlike tra-
ditional PFM converters, the MAX770–MAX773 switch
using the combination of a peak current limit and a pair
of one-shots that set the maximum on-time (16µs) and
minimum off-time (2.3µs); there is no oscillator. Once
off, the minimum off-time one-shot holds the switch
off for 2.3µs. After this minimum time, the switch either
1) stays off if the output is in regulation, or 2) turns on
again if the output is out of regulation.
The control circuitry allows the ICs to operate in contin-
uous-conduction mode (CCM) while maintaining high
efficiency with heavy loads. When the power switch is
5V/12V/15V or Adjustable, High-Efficiency,
Low IQ, Step-Up DC-DC Controllers
