Rainbow Electronics MAX608 User Manual

19-0438; Rev 0; 9/95

EVALUATION KIT MANUAL

FOLLOWS DATA SHEET

5V or Adjustable, Low-Voltage,

Step-Up DC-DC Controller

_______________General Description

The MAX608 low-voltage step-up controller operates
from a 1.8V to 16.5V input voltage range. Pulse-fre­quency-modulation (PFM) control provides high effi­ciency at heavy loads, while using only 85µA (typical)
when operating with no load. In addition, a logic-con­trolled shutdown mode reduces supply current to 2µA
typical. The output voltage is factory-set at 5V or can be
adjusted from 3V to 16.5V with an external resistor
divider.

The MAX608 is ideal for two- and three-cell battery­powered systems. An operating frequency of up to
300kHz allows use with small surface-mount compo­nents.

The MAX608 operates in “bootstrapped” mode only
(with the chip supply, OUT, connected to the DC-DC
output). For a 12V output without external resistors, or
for nonbootstrapped applications (chip supply connect­ed to input voltage), refer to the pin-compatible
MAX1771. The MAX608 is available in 8-pin DIP and
SO packages.

________________________Applications

High-Efficiency DC-DC Converters
Battery-Powered Applications
Positive LCD-Bias Generators
Portable Communicators

____________________________Features

♦ 1.8V to 16.5V Input Range
♦ 85% Efficiency for 30mA to 1.5A Load Currents
♦ Up to 10W Output Power
♦ 110µA Max Supply Current
♦ 5µA Max Shutdown Current
♦ Preset 5V or Adjustable Output (3V to 16.5V)
♦ Current-Limited PFM Control Scheme
♦ Up to 300kHz Switching Frequency
♦ Evaluation Kit Available

______________Ordering Information

PART

MAX608C/D
MAX608EPA
MAX608ESA

* Contact factory for dice specifications.

TEMP. RANGE PIN-PACKAGE

0°C to +70°C

-40°C to +85°C

-40°C to +85°C 8 SO

Dice*
8 Plastic DIP

MAX608

__________Typical Operating Circuit

INPUT 

1.8V TO V

OUT

OUTPUT

5V

ON/OFF

MAX608

SHDN
REF

FB AGND GND

________________________________________________________________

EXT

CS

OUT

N

__________________Pin Configuration

TOP VIEW

EXT

1
2

OUT

SHDN

MAX608

FB

3
4

DIP/SO

Maxim Integrated Products

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

CS

8

GND

7

AGND

6

REF

5

1

5V or Adjustable, Low-Voltage,
Step-Up DC-DC Controller

ABSOLUTE MAXIMUM RATINGS

Supply Voltage

OUT to GND.............................................................-0.3V, 17V

EXT, CS, REF, SHDN, FB to GND ...............-0.3V, (V

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

Continuous Power Dissipation (T

Plastic DIP (derate 9.09mW/°C above +70°C) ............727mW

SO (derate 5.88mW/°C above +70°C).........................471mW

MAX608

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.

= +70°C)

A

OUT

+ 0.3V)

ELECTRICAL CHARACTERISTICS

(V

= 5V, I

OUT

= +25°C.)

T

A

PARAMETER

Input Voltage Range
(Note 2)

Minimum Start-Up Voltage No load 1.6 1.8 V

Supply Current

Output Voltage (Note 3) V

Output Voltage Line
Regulation (Note 4)

Output Voltage Load
Regulation (Note 4)

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

Efficiency 87

Reference Voltage

REF Load Regulation -4 10 mV0µA ≤ I
REF Line Regulation

FB Trip Point Voltage
(Note 5)

FB Input Current I
SHDN Input High Voltage

SHDN Input Low Voltage
SHDN Input Current I

= 0mA, TA= -40°C to +85°C where indicated. TA= -25°C to +85°C for all other limits. Typical values are at

LOAD

SYMBOL CONDITIONS MIN TYP MAX UNITS

TA= -25°C to +85°C 1.8 16.5
TA= -40°C to +85°C (Note 1) 1.9 16.5

V

= 16.5V,

OUT

SHDN ≤ 0.4V
V

= 10V,

OUT

SHDN ≥ 1.6V
VIN= 2.0V to 5.0V,

over full load range,
circuit of Figure 2a

VIN= 2.7V to 4.0V, V
circuit of Figure 2a

VIN= 2V, V
circuit of Figure 2a

(min) 1.8 2.3 2.8

OFF

VIN= 4V, V
circuit of Figure 2a

I

V

REF =

REF

3V ≤ V

TA= -25°C to +85°C

V

FB

TA= -40°C to +85°C (Note 1) 1.4475 1.5525
TA= -25°C to +85°C

FB

TA= -40°C to +85°C (Note 1) ±40

V

V

IH

OUT

V

V

IL

OUT

V

IN

OUT

= 5V, I

OUT

= 5V, I

OUT

0µA

≤ 100µA

REF

≤ 16.5V 40 100

OUT

= 1.8V to 16.5V 1.6
= 1.8V to 16.5V 0.4
= 16.5V, SHDN = 0V or 16.5V ±1

Operating Temperature Range ...........................-40°C to +85°C

Junction Temperature......................................................+150°C

Storage Temperature Range.............................-65°C to +160°C

Lead Temperature (soldering, 10sec).............................+300°C

TA= -25°C to +85°C

T

= -25°C to +85°C

A

TA= -25°C to +85°C
TA= -40°C to +85°C (Note 1) 4.800 5.0 5.200

= 5V, I

OUT

= 0mA to 500mA,

LOAD

LOAD

TA= -25°C to +85°C 1.4625 1.5 1.5375
TA= -40°C to +85°C (Note 1) 1.4475 1.5525

LOAD

= 500mA,

= 500mA,

4.825 5.0 5.175

1.4625 1.5 1.5375

85 110

25

7 mV/V

60 mV/A

-4 ±20

120TA= -40°C to +85°C (Note 1)

10TA= -40°C to +85°C (Note 1)

V

µA

µA

µs
µs

%

V

µV/V

V

nA

V
V

µA

_______________________________________________________________________________________

2

5V or Adjustable, Low-Voltage,

Step-Up DC-DC Controller

ELECTRICAL CHARACTERISTICS (continued)

(V

= 5V, I

OUT

= +25°C.)

T

A

PARAMETER

Current-Limit Trip Level V

CS Input Current I
EXT Rise Time V
EXT Fall Time V

= 0mA, TA= -40°C to +85°C where indicated. TA= -25°C to +85°C for all other limits. Typical values are at

LOAD

SYMBOL CONDITIONS

V

CS

CS

= 3V to 16.5V

OUT

= 5V, 1nF from EXT to GND 50

OUT

= 5V, 1nF from EXT to GND 50

OUT

TA= -25°C to +85°C
TA= -40°C to +85°C (Note 1)

MIN TYP MAX

85 100 115
80 120

0.01 ±1

UNITS

mV

µA

ns

EXT On-Resistance EXT = high or low 15 30 Ω

Note 1: Limits over this temperature range are guaranteed by design.
Note 2: The MAX608 must be operated in bootstrapped mode with OUT connected to the DC-DC circuit output. The minimum output

voltage set point is +3V.

Note 3: Output voltage guaranteed using preset voltages. See Figures 4a–4d for output current capability versus input voltage.
Note 4: Output voltage line and load regulation depend on external circuit components.
Note 5: Operation in the external-feedback mode is guaranteed to be accurate to the V

trip level, and does not include resistor tolerance.

FB

__________________________________________Typical Operating Characteristics

(TA = +25°C, unless otherwise noted.)

100

90

80

EFFICIENCY (%)

70

EFFICIENCY vs. LOAD CURRENT

= 5V)

(V

OUT

V

= 4.0V

IN

V

= 3.5V

IN

V

= 3.0V

= 2.0V

IN

V

IN

MAX608-01

EFFICIENCY (%)

EFFICIENCY vs. LOAD CURRENT

IN

= 9.0V

V

IN

(V

V

= 3.0V

100

V

90

80

70

OUT

IN

= 12V)

= 6.0V

V

= 5.0V

IN

V

= 2.0V

IN

MAX608-02

EFFICIENCY (%)

EFFICIENCY vs. LOAD CURRENT

(V

100

90

80

70

OUT

= 3.3V)

V

= 3.0V

IN

V

IN

= 2.0V

MAX608

MAX608-03

60

1 10 100 1000

LOAD CURRENT (mA)

LOAD CURRENT vs.

MINIMUM START-UP 

700
600

500

400

300

200

LOAD CURRENT (mA)

100

0

1.8 2.2 2.6 3.0 3.4 3.8 4.0

INPUT VOLTAGE

V

= 5V

OUT

CIRCUIT OF FIGURE 2a
EXTERNAL FET THRESHOLD LIMITS
FULL-LOAD START-UP BELOW 3.7V

MINIMUM START-UP VOLTAGE (V)

_______________________________________________________________________________________

60

MAX608-04

LOAD CURRENT (mA)

1 10 100 1000

LOAD CURRENT (mA)

LOAD CURRENT vs.

MINIMUM START-UP

500

400

300

200

100

0

1.8 2.2 2.6 3.0 3.4 3.8 4.0

INPUT VOLTAGE

V

= 12V

OUT

CIRCUIT OF FIGURE 2b
EXTERNAL FET THRESHOLD LIMITS
FULL-LOAD START-UP BELOW 3.6V

MINIMUM START-UP VOLTAGE (V)

MAX608-05

60

1 10 100 1000

LOAD CURRENT (mA)

SUPPLY CURRENT

200

150

100

SUPPLY CURRENT (µA)

50

0

vs. INPUT VOLTAGE

01 234 5

INPUT VOLTAGE (V)

MAX608-06

3

5V or Adjustable, Low-Voltage,
Step-Up DC-DC Controller

____________________________Typical Operating Characteristics (continued)

(TA = +25°C, unless otherwise noted.)

EXT RISE/FALL TIME vs. SUPPLY VOLTAGE

250

200

MAX608

150

100

EXT RISE/FALL TIME (ns)

50

0

2

MAXIMUM SWITCH ON-TIME vs.

16.5



16.0

ON(max) (µs)

t



15.5

-30 0 30 60

-60

68

4

SUPPLY VOLTAGE (V)

TEMPERATURE

TEMPERATURE (°C)

C

EXT

C

EXT

C

EXT

C

EXT



= 2200pF



= 1000pF



= 470pF



= 100pF



90

10

120 150

MAX608-07

REFERENCE OUTPUT RESISTANCE (Ω)

12

MAX608-10

SHUTDOWN CURRENT (µA)

REFERENCE OUTPUT RESISTANCE vs.

250

200

150

100

50

0

-60 -20 60 140

TEMPERATURE

10µA

50µA

-40 0 8040 120

20 100

TEMPERATURE (°C)

SHUTDOWN CURRENT vs. TEMPERATURE

4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5
0

-60 -20 60 140

V+ = 8V

V+ = 4V

TEMPERATURE (°C)

V+ = 15V

20 100-40 0 8040 120

100µA

MAX608-08

MAX608-11

REFERENCE vs. TEMPERATURE

1.506

1.504

1.502

1.500

1.498

REFERENCE (V)

1.496

1.494

1.492

-60 -20 60 140

MINIMUM SWITCH OFF-TIME vs.

2.30



2.25

OFF(min) (µs)

t



2.20

-30 0 30 60

-60



20 100-40 0 8040 120

TEMPERATURE (°C)

TEMPERATURE



TEMPERATURE (°C)

MAX608-09

MAX608-12



120 150

90

HEAVY-LOAD SWITCHING WAVEFORMS

(V

= 5V)

OUT

V

A

B

C

= 930mA, V

OUT

2µs/div

OUT

= 5V

VIN = 3V, I
A = EXT VOLTAGE, 5V/div
B = INDUCTOR CURRENT, 1A/div
C = V

RIPPLE, 50mV/div, AC-COUPLED

OUT

_______________________________________________________________________________________

4

OUT

0V
I

LIM

0A

MEDIUM-LOAD SWITCHING WAVEFORMS

(V

= 5V)

OUT

A

B

C

= 490mA, V

OUT

20µs/div

OUT

= 5V

VIN = 3V, I
A = EXT VOLTAGE, 5V/div
B = INDUCTOR CURRENT, 1A/div
C = V

RIPPLE, 50mV/div, AC-COUPLED

OUT

V

OUT

0V
I

LIM

0A