Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsPMICsPMIC - voltage regulators - DC DC switch controllers SOIC 8

_______________General Description

The 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.

________________________Applications

Palmtops/Handy-Terminals

High-Efficiency DC-DC Converters

Battery-Powered Applications

Positive LCD-Bias Generators

Portable Communicators

Flash Memory Programmers

____________________________Features

♦ 90% Efficiency for 10mA to 1A Load Currents

♦ Up to 15W Output Power

♦ 110µA Max Supply Current

♦ 5µA Max Shutdown Current

♦ 2V 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 Adjustable

♦ Current-Limited PFM Control Scheme

♦ 300kHz 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 I

, Step-Up DC-DC Controllers

________________________________________________________________

Maxim Integrated Products

GND

AGND

REF

SHDN

V+

EXT

MAX770

MAX771

MAX772

DIP/SO

_________________Pin Configurations

FB AGND GND

V+

EXT

REF

SHDN

ON/OFF

OUTPUT

12V

INPUT

2V TO V

OUT

MAX771

__________Typical Operating Circuit

PART TEMP. RANGE PIN-PACKAGE

MAX770CPA

0°C to +70°C Plastic DIP

MAX770CSA 0°C to +70°C 8 SO

MAX770C/D 0°C to +70°C Dice*

MAX770EPA -40°C to +85°C 8 Plastic DIP

MAX770ESA -40°C to +85°C 8 SO

MAX770MJA -55°C to +125°C 8 CERDIP**

TOP VIEW

Pin Configurations continued at end of data sheet.

19-0202; Rev 2; 11/96

EVALUATION KIT MANUAL

FOLLOWS DATA SHEET

For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.

For small orders, phone 408-737-7600 ext. 3468.

Summary of content (20 pages)

PAGE 1
9-0202; Rev 2; 11/96 L MANUA ION KIT HEET T A U L EVA TA S WS DA FOLLO 5V/12V/15V or Adjustable, High-Efficiency, Low IQ, Step-Up DC-DC Controllers ________________________Applications Palmtops/Handy-Terminals High-Efficiency DC-DC Converters Battery-Powered Applications ____________________________Features ♦ 90% Efficiency for 10mA to 1A Load Currents ♦ Up to 15W Output Power ♦ 110µA Max Supply Current ♦ 5µA Max Shutdown Current ♦ 2V to 16.
PAGE 2
MAX770–MAX773 5V/12V/15V or Adjustable, High-Efficiency, Low IQ, Step-Up DC-DC Controllers ABSOLUTE MAXIMUM RATINGS Supply 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.
PAGE 3
5V/12V/15V or Adjustable, High-Efficiency, Low IQ, Step-Up DC-DC Controllers MAX770–MAX773 ELECTRICAL CHARACTERISTICS (continued) (V+ = 5V, ILOAD = 0mA, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETERS SYMBOL CONDITIONS REF Load Regulation 0µA ≤ IREF ≤ 100µA REF Line Regulation 3V ≤ V+ ≤ 16.
PAGE 4
__________________________________________Typical Operating Characteristics (TA = +25°C, unless otherwise noted.) MAX771 EFFICIENCY vs. OUTPUT CURRENT (BOOTSTRAPPED) 50 0.1 1 EFFICIENCY (%) 60 VIN = 3V 50 0.001 0.01 MAX771 EFFICIENCY vs. OUTPUT CURRENT (NON-BOOTSTRAPPED) MAX770–3-04 VIN = 9V 90 VIN = 6V VIN = 5V 80 VOUT = 12V CIRCUIT OF FIGURE 2b 50 0.1 1 0.1 VOUT = 5V CIRCUIT OF FIGURE 2a 500 400 300 ABOVE 3.4V, THE CIRCUIT STARTS UP UNDER MAXIMUM LOAD CONDITIONS 200 1.
PAGE 5
V/12V/15V or Adjustable, High-Efficiency, Low IQ, Step-Up DC-DC Controllers REFERENCE OUTPUT RESISTANCE vs. TEMPERATURE REFERENCE vs. TEMPERATURE 200 1.504 10µA REFERENCE (V) 1.502 150 100 50µA 1.500 1.498 1.496 100µA 50 MAX770–3-11 1.506 MAX770–3-10 REFERENCE OUTPUT RESISTANCE (Ω) 250 1.494 1.492 0 -60 -40 -20 -60 -40 -20 0 20 40 60 80 100 120 140 0 20 40 60 80 100 120 140 TEMPERATURE (°C) TEMPERATURE (°C) MAXIMUM SWITCH ON-TIME vs. TEMPERATURE SHUTDOWN CURRENT vs.
PAGE 6
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 LIGHT-LOAD SWITCHING WAVEFORMS MAX770 HEAVY-LOAD SWITCHNG WAVEFORMS VOUT 0 ILIM A A ILIM ILIM 2 B 2 B 0 0 C C 20µs/div V+ = 3V, IOUT = 165mA A: EXT VOLTAGE, 5V/div B: INDUCTOR CURRENT, 1A/div C: VOUT RIPPLE 100mV/div, AC-COUPLED 20µs/div VIN = 2.9V, IOUT = 0.
PAGE 7
5V/12V/15V or Adjustable, High-Efficiency, Low IQ, Step-Up DC-DC Controllers MAX770 EXITING SHUTDOWN A 0 B 0 200µs/div VIN = 3V, IOUT = 0.5A A: SHDN, 2V/div B: VOUT, 2V/div ______________________________________________________________Pin Description PIN MAX770 MAX771 MAX772 MAX773 1 NAME FUNCTION — EXT 2 3 V+ 3 6 FB 4 7 SHDN 5 8 REF 6 — AGND Gate drive for external N-channel power transistor Power-supply input.
PAGE 8
MAX770–MAX773 5V/12V/15V or Adjustable, High-Efficiency, Low IQ, Step-Up DC-DC Controllers _________________________________________________Pin Description (continued) PIN MAX770 MAX771 MAX772 MAX773 — 12 EXTL — 13 EXTH — 14 V15 NAME FUNCTION Low-level gate/base drive for external power transistor. Connect to the gate of an external N-channel MOSFET or to the base of an external NPN transistor. High-level gate/base drive for external power transistor.
PAGE 9
5V/12V/15V or Adjustable, High-Efficiency, Low IQ, Step-Up DC-DC Controllers V12 V5 MAX770–MAX773 LBO V15 FB V+ DUAL-MODE COMPARATOR MAX773 ONLY LBI N MAX770–MAX773 N SHDN 200mV BIAS CIRCUITRY 1.5V REFERENCE REF ERROR COMPARATOR ONE-SHOT Q TRIG N MAX770 MAX771 MAX772 V+ 6V SGND F/F S Q EXT CONTROL R EXTH LOW-VOLTAGE OSCILLATOR 2.5V ONE-SHOT TRIG MAX773 ONLY EXTL Q CURRENT-SENSE AMPLIFIER 0.2V 0.1V EXT MAX770 MAX771 MAX772 CS Figure 1.
PAGE 10
MAX770–MAX773 5V/12V/15V or Adjustable, High-Efficiency, Low IQ, Step-Up DC-DC Controllers VIN = 5V VIN = 3V C2 0.1µF V+ 5 REF C3 0.1µF C2 0.1µF 2 4 SHDN L1 22µH MAX770 3 FB C1 100µF EXT 1 2 V+ 5 REF D1 1N5817 VOUT = 5V @ 1A C3 0.1µF 4 SHDN MAX771 3 FB N EXT 1 CS 6 AGND GND C4 300µF CS 8 RSENSE 100mΩ GND 7 Figure 2b. 12V Preset Output, Bootstrapped VIN = 4V VIN = 5V C1 68µF C2 0.1µF C2 0.
PAGE 11
5V/12V/15V or Adjustable, High-Efficiency, Low IQ, Step-Up DC-DC Controllers 1 V12 14 V15 SGND 8 REF MAX773 C3 0.1µF R3 10k (1%) C1 47µF VIN 10 C1 100k L1 22µH D1 1N5817 LBO 4 VOUT = 12V Si9410DY 5 LBI EXTH 13 10 SGND 4 LBO C3 0.1µF N C4 CS 11 7 FB LBI RSENSE GND 9 ZTX694B CS 11 V15 14 V12 1 SHDN FB R4 = R3 RSENSE 0.4Ω 6 R1 34k GND 9 NOMINAL MAX 11.0 11.4 C4 150µF 12 V5 2 VTRIP (V) MIN 10.
PAGE 12
MAX770–MAX773 5V/12V/15V or Adjustable, High-Efficiency, Low IQ, Step-Up DC-DC Controllers VIN = 24V TO 28V C1 47µF C2 0.1µF RSHUNT 3k D1 MUR115 3 10 4 LBO RSHUNT MAX773 EXTH 13 EXTL 12 N Si9420DY 3 V+ C4 100µF CS 11 8 REF MAX773 V15 14 C2 0.1µF RSENSE 1.0Ω 6V (typ) V12 1 5 LBI 7 VOUT = 100V @ 10mA v+ SGND C3 0.1µF VIN L1 250µH V5 2 6 FB SHDN GND 9 10 SGND R2 732k (1%) R1 11.3k (1%) RSHUNT = R2 = (R1) ( VREF = 1.
PAGE 13
5V/12V/15V or Adjustable, High-Efficiency, Low IQ, Step-Up DC-DC Controllers Shutdown Mode When SHDN is high, the MAX770–MAX773 enter shutdown mode. In this mode, the internal biasing circuitry is turned off (including the reference) and V OUT falls to a diode drop below VIN (due to the DC path from the input to the output). In shutdown mode, the supply current drops to less than 5µA. SHDN is a TTL/CMOS logic-level input. Connect SHDN to GND for normal operation.
PAGE 14
MAX770–MAX773 5V/12V/15V or Adjustable, High-Efficiency, Low IQ, Step-Up DC-DC Controllers Table 1. Bootstrapped vs. Non-Bootstrapped Operation PARAMETER BOOTSTRAPPED* NON-BOOTSTRAPPED Gate Drive GND to VOUT GND to V+ FET On Resistance Lower Higher Gate-Drive Capacitive Losses Higher Lower No-Load Supply Current Higher 2V to 16.5V (MAX770/MAX771/MAX772), (internal feedback resistors) 3V to 16.5V (MAX770/MAX771/MAX772), (external feedback resistors) 3V to 16.
PAGE 15
5V/12V/15V or Adjustable, High-Efficiency, Low IQ, Step-Up DC-DC Controllers 3.0 MAXIMUM OUTPUT CURRENT (A) MAXIMUM OUTPUT CURRENT (A) 3.5 VOUT = 5V L = 22µH RSENSE = 40mΩ 2.5 RSENSE = 50mΩ 2.0 RSENSE = 75mΩ 1.5 1.0 RSENSE = 100mΩ VOUT = 12V L = 22µH 3.0 RSENSE = 40mΩ RSENSE = 50mΩ 2.5 RSENSE = 75mΩ 2.0 1.5 1.0 RSENSE = 100mΩ 0.5 0.5 RSENSE = 200mΩ RSENSE = 200mΩ 0 0 2 3 4 INPUT VOLTAGE (V) 3.5 2 5 Figure 7a. Maximum Output Current vs.
PAGE 16
MAX770–MAX773 5V/12V/15V or Adjustable, High-Efficiency, Low IQ, Step-Up DC-DC Controllers IC(PEAK) MAX770 MAX771 MAX772 L MAX773 IB EXT N RBASE EXTH NPN EXTL CS CS RSENSE RSENSE Figure 8a. Use an N-Channel MOSFET with the MAX770/MAX771/MAX772 L MAX773 Figure 8c. Using an NPN Transistor with the MAX773 preferably under 20mΩ. To minimize radiated noise, use a toroid, a pot core, or a shielded coil. Table 2 lists inductor suppliers and specific recommended inductors.
PAGE 17
5V/12V/15V or Adjustable, High-Efficiency, Low IQ, Step-Up DC-DC Controllers Continuing with the example, ∆V+ = 17nC/0.1µF = 170mV. Use I GATE when calculating the appropriate shunt resistor. See the Shunt Regulator Operation section. Figure 2a’s application circuit uses an MTD3055EL logic-level N-FET with a guaranteed threshold voltage (V TH) of 2V. Figure 2b’s application circuit uses an 8-pin Si9410DY surface-mount N-FET that has 50mΩ on resistance with 4.5V VGS, and a guaranteed VTH of less than 3V.
PAGE 18
MAX770–MAX773 5V/12V/15V or Adjustable, High-Efficiency, Low IQ, Step-Up DC-DC Controllers Smaller capacitors are acceptable for light loads or in applications that can tolerate higher output ripple. Since the output filter capacitor’s ESR affects efficiency, use low-ESR capacitors for best performance. The smallest low-ESR surface-mount tantalum capacitors currently available are the Sprague 595D series.
PAGE 19
5V/12V/15V or Adjustable, High-Efficiency, Low IQ, Step-Up DC-DC Controllers Layout Considerations Due to high current levels and fast switching waveforms, which radiate noise, proper PC board layout is essential. Protect sensitive analog grounds by using a star ground configuration. 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).
PAGE 20
MAX770–MAX773 5V/12V/15V or Adjustable, High-Efficiency, Low IQ, Step-Up DC-DC Controllers ___Ordering Information (continued) PART TEMP.