Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsPMICsPMIC - DC/DC voltage regulator Converter/amplifier PDIP 8

_______________General Description

The MAX764/MAX765/MAX766 inverting switching regu-

lators are highly efficient over a wide range of load cur-

rents, delivering up to 1.5W. A unique, current-limited,

pulse-frequency-modulated (PFM) control scheme com-

bines the benefits of traditional PFM converters with the

benefits of pulse-width-modulated (PWM) converters.

Like PWM converters, the MAX764/MAX765/MAX766 are

highly efficient at heavy loads. Yet because they are PFM

devices, they use less than 120µA of supply current (vs.

2mA to 10mA for a PWM device).

The input voltage range is 3V to 16V. The output volt-

age is preset at -5V (MAX764), -12V (MAX765), or -15V

(MAX766); it can also be adjusted from -1V to -16V

using two external resistors (Dual Mode

). The maxi-

mum operating V

- V

OUT

differential is 20V.

These devices use miniature external components; their

high switching frequencies (up to 300kHz) allow for less

than 5mm diameter surface-mount magnetics. A stan-

dard 47µH inductor is ideal for most applications, so no

magnetics design is necessary.

An internal power MOSFET makes the MAX764/MAX765/

MAX766 ideal for minimum component count, low- and

medium-power applications. For increased output drive

capability or higher output voltages, use the

MAX774/MAX775/MAX776 or MAX1774, which drive an

external power P-channel MOSFET for loads up to 5W.

________________________Applications

LCD-Bias Generators

Portable Instruments

LAN Adapters

Remote Data-Acquisition Systems

Battery-Powered Applications

____________________________Features

♦ High Efficiency for a Wide Range of Load Currents

♦ 250mA Output Current

♦ 120µA Max Supply Current

♦ 5µA Max Shutdown Current

♦ 3V to 16V Input Voltage Range

♦ -5V (MAX764), -12V (MAX765), -15V (MAX766),

or Adjustable Output from -1V to -16V

♦ Current-Limited PFM Control Scheme

♦ 300kHz Switching Frequency

♦ Internal, P-Channel Power MOSFET

______________Ordering Information

Ordering Information continued on last page.

* Dice are tested at T

= +25°C, DC parameters only.

**Contact factory for availability and processing to MIL-STD-883.

MAX764/MAX765/MAX766

-5V/-12V/-15V or Adjustable,

High-Efficiency, Low I

DC-DC Inverters

________________________________________________________________

Maxim Integrated Products

V+

GND

REF

SHDN

OUT

MAX764

MAX765

MAX766

DIP/SO

TOP VIEW

__________________Pin Configuration

GND

MAX764

SHDN

OUT

ON/OFF

REF

47µH

OUTPUT

-5V

INPUT

3V TO 15V

V+

__________Typical Operating Circuit

Call toll free 1-800-998-8800 for free samples or literature.

19-0176; Rev 0; 6/94

PART

MAX764CPA

MAX764CSA

MAX764C/D 0°C to +70°C

0°C to +70°C

TEMP. RANGE PIN-PACKAGE

8 Plastic DIP

8 SO

Dice*

MAX764EPA

MAX764ESA -40°C to +85°C

-40°C to +85°C 8 Plastic DIP

8 SO

MAX764MJA -55°C to +125°C 8 CERDIP**

MAX765CPA

MAX765CSA

MAX765C/D 0°C to +70°C

0°C to +70°C

0°C to +70°C 8 Plastic DIP

8 SO

Dice*

MAX765EPA

MAX765ESA -40°C to +85°C

-40°C to +85°C 8 Plastic DIP

8 SO

MAX765MJA -55°C to +125°C 8 CERDIP**

Evaluation Kit

Available

Summary of content (12 pages)

PAGE 1
9-0176; Rev 0; 6/94 it K tion lua able a v E il Ava -5V/-12V/-15V or Adjustable, High-Efficiency, Low IQ DC-DC Inverters ____________________________Features ♦ High Efficiency for a Wide Range of Load Currents ________________________Applications LCD-Bias Generators Portable Instruments LAN Adapters Remote Data-Acquisition Systems Battery-Powered Applications ♦ 250mA Output Current ♦ 120µA Max Supply Current ♦ 5µA Max Shutdown Current ♦ 3V to 16V Input Voltage Range ♦ -5V (MAX764), -12V (MAX765), -15V
PAGE 2
MAX764/MAX765/MAX766 -5V/-12V/-15V or Adjustable, High-Efficiency, Low IQ DC-DC Inverters ABSOLUTE MAXIMUM RATINGS V+ to GND ..............................................................-0.3V to +17V OUT to GND ...........................................................+0.5V to -17V Maximum Differential (V+ to OUT) ......................................+21V REF, SHDN, FB to GND ...............................-0.3V to (V+ + 0.3V) LX to V+..................................................................+0.
PAGE 3
-5V/-12V/-15V or Adjustable, High-Efficiency, Low IQ DC-DC Inverters (V+ = 5V, ILOAD = 0mA, CREF = 0.1µF, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER SYMBOL CONDITIONS ILXI + (V+) ≤ 20V LX Leakage Current LX On-Resistance Peak Current at LX IPEAK MIN TYP MAX MAX76_C ±5 MAX76_E ±10 MAX76_M ±30 IVOUTI + (V+) ≥ 10V IVOUTI + (V+) ≥ 10V 1.4 0.5 0.75 UNITS µA 2.5 Ω A Maximum Switch On-Time tON 12 16 20 µs Minimum Switch Off-Time tOFF 1.8 2.
PAGE 4
____________________________Typical Operating Characteristics (continued) (V+ = 5V, VOUT = -5V, TA = +25°C, unless otherwise noted.) NO-LOAD SUPPLY CURRENT vs. SUPPLY VOLTAGE 400 300 200 VOUT = -12V 100 VOUT = -15V 0 80 75 70 65 MAX764 -06 90 85 80 75 70 V+ = 5V 65 60 55 50 3 4 5 6 7 8 9 10 11 12 13 14 15 16 SUPPLY VOLTAGE (V) TEMPERATURE (°C) SHUTDOWN CURRENT vs. TEMPERATURE MAXIMUM SWITCH ON-TIME vs. TEMPERATURE MINIMUM SWITCH OFF-TIME vs. TEMPERATURE 2.0 1.5 V+ = 8V 1.0 16.6 16.
PAGE 5
-5V/-12V/-15V or Adjustable, High-Efficiency, Low IQ DC-DC Inverters PEAK CURRENT AT LX vs. TEMPERATURE 0.90 CURRENT AT LX (A) IVOUTI + (V+) = 10V 1.8 1.6 IVOUTI + (V+) = 15V 1.4 1.2 IVOUTI + (V+) = 20V 0.85 IVOUTI + (V+) = 15V 0.80 0.75 0.70 1.0 IVOUTI + (V+) = 10V IVOUTI + (V+) = 20V 250 200 0 20 40 60 80 100 120 140 IREF = 50µA 100 50 IREF = 100µA 0 -60 -40 -20 TEMPERATURE (°C) 0 20 40 60 80 100 120 140 -60 -40 -20 TEMPERATURE (°C) SUPPLY CURRENT vs.
PAGE 6
MAX764/MAX765/MAX766 -5V/-12V/-15V or Adjustable, High-Efficiency, Low IQ DC-DC Inverters ____________________________Typical Operating Characteristics (continued) (V+ = 5V, VOUT = -5V, TA = +25°C, unless otherwise noted.
PAGE 7
-5V/-12V/-15V or Adjustable, High-Efficiency, Low IQ DC-DC Inverters DISCONTINUOUS CONDUCTION AT HALF CURRENT LIMIT CONTINUOUS CONDUCTION AT FULL CURRENT LIMIT A A B B 0A 0A 0V C 5µs/div CIRCUIT OF FIGURE 2, V+ = 5V, VOUT = -5V, ILOAD = 80mA A: OUTPUT RIPPLE, 100mV/div B: INDUCTOR CURRENT, 500mA/div C: LX WAVEFORM, 10V/div 0V C 5µs/div CIRCUIT OF FIGURE 2, V+ = 5V, VOUT = -5V, ILOAD = 240mA A: OUTPUT RIPPLE, 100mV/div B: INDUCTOR CURRENT, 500mA/div C: LX WAVEFORM, 10V/div ______________________
PAGE 8
MAX764/MAX765/MAX766 -5V/-12V/-15V or Adjustable, High-Efficiency, Low IQ DC-DC Inverters FB COMPARATOR MAX764 MAX765 MAX766 REF SHDN ERROR COMPARATOR OUT V+ N V+ 1.5V REFERENCE Q TRIG ONE-SHOT FROM V+ S TRIG Q Q R P CURRENT COMPARATOR FROM OUT LX ONE-SHOT 0.2V (FULL CURRENT) CURRENT CONTROL CIRCUITS 0.1V (HALF CURRENT) FROM V+ GND Figure 1.
PAGE 9
-5V/-12V/-15V or Adjustable, High-Efficiency, Low IQ DC-DC Inverters VIN 1 C1 120µF 20V 7 V+ OUT C2 0.1µF 3 2 4 SHDN MAX764 MAX765 MAX766 FB 6 V+ D1 1N5817 8 LX VOUT REF C4 68µF 20V GND C3 0.1µF L1 47µH 5 PRODUCT OUTPUT VOLTAGE (V) INPUT VOLTAGE (V) MAX764 MAX765 MAX766 -5 -12 -15 3 to 15 3 to 8 3 to 5 Figure 2. Fixed Output Voltage Operation VIN C1 120µF 20V C2 0.1µF R2 1 3 2 V+ OUT SHDN MAX764 V+ MAX765 MAX766 FB LX 7 6 8 D1 1N5817 R1 4 REF GND C3 0.
PAGE 10
MAX764/MAX765/MAX766 -5V/-12V/-15V or Adjustable, High-Efficiency, Low IQ DC-DC Inverters Modes of Operation Diode Selection When delivering high output currents, the MAX764/ MAX765/MAX766 operate in continuous-conduction mode. In this mode, current always flows in the inductor, and the control circuit adjusts the duty-cycle of the switch on a cycle-by-cycle basis to maintain regulation without exceeding the switch-current capability. This provides excellent load-transient response and high efficiency.
PAGE 11
-5V/-12V/-15V or Adjustable, High-Efficiency, Low IQ DC-DC Inverters Layout Considerations Proper PC board layout is essential to reduce noise generated by high current levels and fast switching waveforms. Minimize ground noise by connecting GND, the input bypass capacitor ground lead, and the output filter capacitor ground lead to a single point (star ground configuration). Also minimize lead lengths to reduce stray capacitance, trace resistance, and radiated noise.
PAGE 12
MAX764/MAX765/MAX766 -5V/-12V/-15V or Adjustable, High-Efficiency, Low IQ DC-DC Inverters _Ordering Information (continued) PART TEMP. RANGE ___________________Chip Topography PIN-PACKAGE MAX766CPA 0°C to +70°C 8 Plastic DIP MAX766CSA MAX766C/D MAX766EPA MAX766ESA MAX766MJA 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 8 SO Dice* 8 Plastic DIP 8 SO 8 CERDIP** LX OUT * Dice are tested at TA = +25°C, DC parameters only.