Document
MAX774/MAX775/MAX776
19-0191; Rev 2; 12/02
EVAALVUAAILTAIOBNLEKIT
-5V/-12V/-15V or Adjustable, High-Efficiency, Low IQ Inverting DC-to-DC Controllers
General Description
The MAX774/MAX775/MAX776 inverting switching regulators deliver high efficiency over three decades of load current. A unique current-limited, pulsefrequency modulated (PFM) control scheme provides the benefits of pulse-width modulation (high efficiency with heavy loads), while using less than 100µA of supply current (vs. 2mA to 10mA for PWM converters). The result is high efficiency over a wide range of loads.
These ICs also use tiny external components; their high switching frequency (up to 300kHz) allows for less than 5mm diameter surface-mount magnetics.
The MAX774/MAX775/MAX776 accept input voltages from 3V to 16.5V, and have preset output voltages of -5V, -12V, and -15V, respectively. Or, the output voltage can be user-adjusted with two resistors. Maximum VIN - VOUT differential voltage is limited only by the breakdown voltage of the chosen external switch transistor.
These inverters use external P-channel MOSFET switches, allowing them to power loads up to 5W. If less power is required, use the MAX764/MAX765/MAX766 inverting switching regulators with on-board MOSFETs.
Applications
LCD-Bias Generators
High-Efficiency DC-to-DC Converters
Battery-Powered Applications
Data Communicators
Features
o 85% Efficiency for 5mA to 1A Load Currents o Up to 5W Output Power o 100µA (max) Supply Current o 5µA (max) Shutdown Current o 3V to 16.5V Input Range o -5V (MAX774), -12V (MAX775), -15V (MAX776),
or Adjustable Output Voltage o Current-Limited PFM Control Scheme o 300kHz Switching Frequency
Ordering Information
PART MAX774CPA MAX774CSA MAX774C/D MAX774EPA MAX774ESA MAX774MJA
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 -55°C to +125°C
*Contact factory for dice specifications.
PIN-PACKAGE 8 Plastic DIP 8 SO Dice* 8 Plastic DIP 8 SO 8 CERDIP
Ordering Information continued on last page.
Typical Operating Circuit
INPUT 3V TO 16V
V+
ON/OFF
MAX774
SHDN
CS EXT
FB
REF OUT
GND
P
OUTPUT -5V
TOP VIEW
Pin Configuration
OUT 1 FB 2
SHDN 3 REF 4
MAX774 MAX775 MAX776
DIP/SO
8 GND 7 EXT 6 CS 5 V+
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
MAX774/MAX775/MAX776
-5V/-12V/-15V or Adjustable, High-Efficiency, Low IQ Inverting DC-to-DC Controllers
ABSOLUTE MAXIMUM RATINGS
Supply Voltages V+ to OUT ...........................................................................21V V+ to GND ..............................................................-0.3V, +17V OUT to GND ........................................................-0.3V, to -17V REF, SHDN, FB, CS...................................-0.3V to (V+ + 0.3V) EXT ...............................................(VOUT - 0.3V) to (V+ + 0.3V)
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 CERDIP (derate 8.00mW/°C above +70°C) ..................640mW
Operating Temperature Ranges: MAX77_C_ _ .........................................................0°C to +70°C MAX77_E_ _ ......................................................-40°C to +85°C MAX77_MJA ...................................................-55°C to +125°C
Maximum Junction Temperatures: MAX77_C_ _/E_ _ ...........................................................+150°C MAX77_MJA..................................................................+175°C
Storage Temperature Range .............................-65°C to +160°C Lead Temperature (soldering, 10s) .................................+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, CREF = 0.1µF, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN TYP MAX
V+ Input Voltage Range
V+
3.0 16.5
V+ = 16.5V, SHDN ≤ 0.4V (operating)
100
Supply Current
V+ = 10V, SHDN ≥ 1.6V (shutdown)
25
V+ = 16.5V, SHDN ≥ 1.6V (shutdown)
4
FB Trip Point
3V ≤ V+ ≤ 16.5V
-10 10
MAX77_C
±50
FB Input Current
IFB MAX77_E MAX77_M
±70 ±90
MAX774
-4.80
-5 -5.20
Output Voltage
VOUT
MAX775 MAX776
-11.52 -14.40
-12 -12.48 -15 -15.60
MAX77_C
1.4700 1.5 1.5300
Reference Voltage
VREF IREF = 0µA
MAX77_E MAX77_M
1.4625 1.4550
1.5 1.5375 1.5 1.5450
REF Load Regulation
0µA ≤ IREF ≤ 100µA
.