Rainbow Electronics MAX773 User Manual

_______________General Description

The MAX770–MAX773 step-up switching controllers pro­vide 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 surface­mount 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 out­put 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 on­board 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 IQ, Step-Up DC-DC Controllers

________________________________________________________________

Maxim Integrated Products

1

1
2
3
4

8
7
6
5

CS
GND
AGND

REF

SHDN

FB

V+

EXT

MAX770
MAX771
MAX772

DIP/SO

_________________Pin Configurations

FB AGND GND

V+

CS

EXT

N

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 [phone].
For small orders, phone [phone] ext. 3468.

MAX770–MAX773

5V/12V/15V or Adjustable, High-Efficiency,
Low IQ, Step-Up DC-DC Controllers

2

_______________________________________________________________________________________

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..................................................-0.3V to (V+ + 0.3V)

V5, V12, V15.............................................................-0.3V to 17V

GND to AGND .........................................................0.1V to -0.1V

I

SGND

..................................................................................50mA

Continuous Power Dissipation (T

A

= +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 (derate 9.09mW/°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, I

LOAD

= 0mA, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at TA= +25°C.)

PARAMETER

SYMBOL CONDITIONS MIN TYP MAX UNITS

Supply Current 85 110

µA

Standby Current

2 5

µA

4

Output Voltage (Note 1)

V+ = 2.0V to 5.0V, over full load range 4.80 5.0 5.20

V

V+ = 2.0V to 12.0V, over full load range 11.52 12.0 12.48
V+ = 2.0V to 15.0V, over full load range 14.40 15.0 15.60

Figure 2a, V+ = 2.7V to 4.5V,
I

LOAD

= 700mA, V

OUT

= 5V

5 mV/V

Figure 2a, V+ = 3V, I

LOAD

= 30mA to 1A,

V

OUT

= 5V

20 mV/A

Maximum Switch On-Time tON(max) 12 16 20

µs

Minimum Switch Off-Time t

OFF

(min) 1.8 2.3 2.8

µs

Efficiency 87 %

Reference Voltage V

REF

I

REF =

0µA

MAX77_C 1.4700 1.5 1.5300

V

MAX77_E 1.4625 1.5 1.5375
MAX77_M 1.4550 1.5 1.5450

Output Voltage Line Regulation
(Note 2)

Output Voltage Load Regulation
(Note 2)

V+ = 4V, I

LOAD

= 500mA, V

OUT

= 5V

V+ = 10.0V, SHDN ≥ 1.6V (shutdown)
V+ = 16.5V, SHDN ≥ 1.6V (shutdown)

V+ = 16.5V, SHDN = 0V (normal operation)

Minimum Start-Up Voltage MAX770/MAX771/MAX772 1.8 2.0 V

MAX770–772 (internal feedback resistors) 2.0 16.5
MAX770–772C/E (external resistors) 3.0 16.5
MAX770–772MJA (external resistors) 3.1 16.5
MAX773C/E 3.0 16.5
MAX773MJD 3.1 16.5

Input Voltage Range V

MAX770–MAX773

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

Low IQ, Step-Up DC-DC Controllers

_______________________________________________________________________________________

3

ELECTRICAL CHARACTERISTICS (continued)

(V+ = 5V, I

LOAD

= 0mA, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at TA= +25°C.)

PARAMETERS

SYMBOL CONDITIONS MIN TYP MAX UNITS

REF Load Regulation

0µA ≤ I

REF

≤ 100µA

MAX77_C/E 4 10

mV

MAX77_M 4 15

REF Line Regulation 3V ≤ V+ ≤ 16.5V 40 100

µV/V

FB Trip-Point Voltage V

FB

MAX77_C 1.4700 1.50 1.5300

VMAX77_E 1.4625 1.50 1.5375

MAX77_M 1.4550 1.50 1.5450

FB Input Current I

FB

MAX77_C ±20

nAMAX77_E ±40

MAX77_M ±60

SHDN Input High Voltage V

IH

V+ = 2.0V to 16.5V 1.6 V

SHDN Input Low Voltage V

IL

MAX77_C/E, V+ = 2.0V to 16.5V 0.4

V

SHDN Input Current ±1

µA
LBI Input Current MAX773, V+ = 16.5V, LBI = 1.5V ±20 nA
LBI Hysteresis MAX773 20

LBI Threshold Voltage MAX773, LBI falling

MAX77_C 1.4700 1.50 1.5300

VMAX77_E 1.4625 1.50 1.5375

MAX77_M 1.4550 1.50 1.5450

LBO Leakage Current MAX773, V+ = 16.5V, V

LBO

= 16.5V 0.01 1.00

µA
LBO Output Voltage Low V

OL

MAX773, V+ = 5V, LBO sinking 1mA 0.1 0.4 V

V+ = 16.5V, SHDN = 0V or V+

mV

Current-Limit Trip Level V

CS

V+ = 5V to 16.5V 170 200 230 mV

V

SHUNT

MAX773, I

SHUNT

= 1mA to 20mA,

SGND = 0V, C

SHUNT

= 0.1µF

5.5 6.3 V

CS Input Current 0.01 ±1

µA
EXT Rise Time V+ = 5V, 1nF from EXT to ground (Note 3) 55 ns
EXT Fall Time V+ = 5V, 1nF from EXT to ground (Note 3) 55 ns
Supply Voltage in

Shunt Mode

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.

LBI Delay 5mV overdrive 2.5 µs

MAX77_M, V+ = 2.0V to 16.5V 0.2

0

1

2

3

4

-75

-50 -25 0

25 50 75 100 125

SUPPLY CURRENT vs. TEMPERATURE

TEMPERATURE (°C)

SUPPLY CURRENT (mA)

V

OUT

= 12V, VIN = 5V
CIRCUIT OF FIGURE 2b
BOOTSTRAPPED MODE

ENTIRE
CIRCUIT

SCHOTTKY DIODE
LEAKAGE EXCLUDED

MAX770–3-07

0

0.2

0.4

0.6

0.8

2

4

6 8

10

12

SUPPLY CURRENT vs. SUPPLY VOLTAGE

SUPPLY VOLTAGE (V)

SUPPLY CURRENT (mA)

V

OUT

= 12V

NON-BOOTSTRAPPED
CIRCUIT OF FIGURE 2c

BOOTSTRAPPED
CIRCUIT OF
FIGURE 2b

MAX770–3-08

0

100

150

200

250

50

2

4

6 8

10

12

EXT RISE/FALL TIME vs. SUPPLY VOLTAGE

V+ (V)

EXT RISE/FALL TIME (ns)

C

EXT

= 2200pF

C

EXT

= 1000pF

C

EXT

= 446pF

C

EXT

= 100pF

MAX770–3-09

100

50

0.001 0.01 0.1 1

MAX772

EFFICIENCY vs. OUTPUT CURRENT

(BOOTSTRAPPED)

60

OUTPUT CURRENT (A)

EFFICIENCY (%)

70

80

90

V

OUT

= 15V, CIRCUIT OF FIGURE 2b

MAX772 SUBSTITUTED FOR MAX771

VIN = 12V

VIN = 9V
VIN = 6V
VIN = 5V

VIN = 3V

MAX770–3-03

50

60

70

80

90

100

0.001 0.01 1

MAX771

EFFICIENCY vs. OUTPUT CURRENT

(BOOTSTRAPPED)

OUTPUT CURRENT (A)

EFFICIENCY (%)

0.1

VIN = 6V

VIN = 5V

VIN = 3V

VIN = 9V

V

OUT

= 12V
CIRCUIT OF
FIGURE 2b

MAX770–3-02

100

50

0.001 0.01 0.1 1

MAX770

EFFICIENCY vs. OUTPUT CURRENT

(BOOTSTRAPPED)

60

OUTPUT CURRENT (A)

EFFICIENCY (%)

70

80

90

VIN = 3V

VIN = 3.5V

V

OUT

= 5V
CIRCUIT OF
FIGURE 2a

VIN = 4V

MAX770–3-01

MAX770–MAX773

5V/12V/15V or Adjustable, High-Efficiency,
Low IQ, Step-Up DC-DC Controllers

4

_______________________________________________________________________________________

__________________________________________Typical Operating Characteristics

(TA = +25°C, unless otherwise noted.)

70

80

90

100

0.001

0.01

0.1

10

1

MAX771

EFFICIENCY vs. OUTPUT CURRENT

(NON-BOOTSTRAPPED)

OUTPUT CURRENT (A)

EFFICIENCY (%)

VIN = 9V

VIN = 6V

VIN = 5V

V

OUT

= 12V
CIRCUIT OF
FIGURE 2c

MAX770–3-04

0

100

200

300

400

500

600

700

1.0

MAX770

LOAD CURRENT vs.

MINIMUM START-UP INPUT VOLTAGE

MINIMUM START-UP INPUT VOLTAGE (V)

LOAD CURRENT (mA)

3.01.5 2.5 3.52.0

ABOVE 3.4V,
THE CIRCUIT
STARTS UP
UNDER
MAXIMUM
LOAD
CONDITIONS

V

OUT

= 5V
CIRCUIT OF
FIGURE 2a

MAX770–3-05

0

100

200

300

400

500

2.0

MAX771

LOAD CURRENT vs.

MINIMUM START-UP INPUT VOLTAGE

MINIMUM START-UP INPUT VOLTAGE (V)

LOAD CURRENT (mA)

4.0

2.5

3.5

3.0

ABOVE 3.5V
THE CIRCUIT
STARTS UP
UNDER
MAXIMUM
LOAD
CONDITIONS

V

OUT

= 12V
CIRCUIT OF
FIGURE 2b

MAX770–3-06

MAX770–MAX773

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

Low IQ, Step-Up DC-DC Controllers

_______________________________________________________________________________________

5

250

0

-60 -20 60 140

REFERENCE OUTPUT RESISTANCE vs.

TEMPERATURE

50

MAX770–3-10

TEMPERATURE (°C)

REFERENCE OUTPUT RESISTANCE (Ω)

20 100

150

-40 0 8040 120

100

200

100µA

50µA

10µA

1.502

-60 -20 60 140

REFERENCE vs. TEMPERATURE

MAX770–3-11

TEMPERATURE (°C)

REFERENCE (V)

20 100-40 0 8040 120

1.500

1.498

1.496

1.494

1.492

1.504

1.506

4.0

-60 -20 60 140

SHUTDOWN CURRENT vs. TEMPERATURE

MAX770–3-12

TEMPERATURE (°C)

I

CC

(µA)

20 100-40 0 8040 120

3.5

3.0

2.5

2.0

1.5

1.0

0.5
0

V+ = 15V

V+ = 4V

V+ = 8V

15.5

16.0

16.5

-60

-30 0 30 60

90

120 150

MAXIMUM SWITCH ON-TIME vs.

TEMPERATURE

TEMPERATURE (°C)

t

ON(MAX) (µs)

MAX770–3-13

2.20

2.25

2.30

-60

-30 0 30 60

90

120 150

MINIMUM SWITCH OFF-TIME vs.

TEMPERATURE

TEMPERATURE (°C)

t

OFF(MIN) (µs)

MAX770–3-14

6.0

7.0

8.0

-60

-30 0 30 60

90

120 150

MAXIMUM SWITCH ON-TIME/

MINIMUM SWITCH OFF-TIME RATIO

vs. TEMPERATURE

TEMPERATURE (°C)

t

ON(MAX)/

t

OFF(MIN) RATIO

MAX770–3-15

7.5

6.5

____________________________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

6

_______________________________________________________________________________________

VIN = 2.9V, I

OUT

= 0.9A
A: EXT VOLTAGE, 5V/div
B: INDUCTOR CURRENT 1A/div
C: V

OUT

RIPPLE 100mV/div, AC-COUPLED

MAX770

HEAVY-LOAD SWITCHNG WAVEFORMS

20µs/div

V

OUT

0 A

I

LIM

I

LIM

2

B

C

0

V+ = 3V, I

OUT

= 165mA
A: EXT VOLTAGE, 5V/div
B: INDUCTOR CURRENT, 1A/div
C: V

OUT

RIPPLE 100mV/div, AC-COUPLED

MAX770

LIGHT-LOAD SWITCHING WAVEFORMS

20µs/div

0

B

A

C

I

LIM

2

I

OUT

= 0.7A

A: V

IN

, 2.7V TO 4.5V, 2V/div

B: V

OUT

RIPPLE, 100mV/div, AC-COUPLED

MAX770

LINE-TRANSIENT RESPONSE

A

B

4.5V

2.7V

0

2ms/div

VIN = 3V
A: LOAD CURRENT 0.5A/div (0A to 1A)
B: V

OUT

RIPPLE, 100mV/div, AC-COUPLED

MAX770

LOAD-TRANSIENT RESPONSE

2ms/div

A

B

0

____________________________Typical Operating Characteristics (continued)

(Circuit of Figure 2a, TA = +25°C, unless otherwise noted.)