Rainbow Electronics MAX861 User Manual

19-0239; Rev 1; 11/96

50mA, Frequency-Selectable,

Switched-Capacitor Voltage Converters

_______________General Description

The MAX860/MAX861 charge-pump voltage converters invert input voltages ranging from +1.5V to +5.5V, or double input voltages ranging from +2.5V to +5.5V. Because of their high switching frequencies, these devices use only two small, low-cost capacitors. Their 50mA output makes switching regulators unnecessary, eliminating inductors and their associated cost, size, and EMI. Greater than 90% efficiency over most of the load-current range, combined with a typical operating current of only 200µA (MAX860), provides ideal performance for both battery-powered and board-level voltage-conversion applications.

A frequency-control (FC) pin provides three switchingfrequencies to optimize capacitor size and quiescent current and to prevent interference with sensitive circuitry. Each device has a unique set of three available frequencies. A shutdown (S—H—D—N–) pin reduces current consumption to less than 1µA. The MAX860/MAX861 are suitable for use in applications where the ICL7660 and MAX660's switching frequencies are too low. The MAX860/MAX861 are available in 8-pin µMAX and SO packages.

________________________Applications

Portable Computers Medical Instruments Interface Power Supplies Hand-Held Instruments Operational-Amplifier Power Supplies

__________Typical Operating Circuit

____________________________Features

♦ 8-Pin, 1.11mm High µMAX Package ♦ Invert or Double the Input Supply Voltage ♦ Three Selectable Switching Frequencies ♦ High Frequency Reduces Capacitor Size ♦ 87% Efficiency at 50mA ♦ 200µA Quiescent Current (MAX860) ♦ 1µA Shutdown Supply Current ♦ 600mV Voltage Drop at 50mA Load ♦ 12Ω Output Resistance

______________Ordering Information

PART

MAX860ISA

MAX860IUA -25°C to +85°C MAX860C/D 0°C to +70°C Dice* MAX860ESA -40°C to +85°C 8 SO MAX860MJA -55°C to +125°C MAX861ISA MAX861IUA -25°C to +85°C 8 µMAX MAX861C/D 0°C to +70°C Dice* MAX861ESA -40°C to +85°C 8 SO MAX861MJA -55°C to +125°C

* Dice are tested at TA= +25°C, DC parameters only.

†

Contact factory for availability.

TEMP. RANGE PIN-PACKAGE

-25°C to +85°C

-25°C to +85°C 8 SO

8 SO 8 µMAX

8 CERDIP

†

MAX860/MAX861

INPUT VOLTAGE +1.5V TO +5.5V

INVERTED NEGATIVE OUTPUT

10µF

DOUBLED POSITIVE OUTPUT

10µF

__________________Pin Configuration

TOP VIEW

SHDN

OUT

C1+

GND

C1-

1 2

MAX860

MAX861

SO/µMAX

Maxim Integrated Products

INPUT

VOLTAGE

+2.5V TO +5.5V

MAX860

MAX861

C1+

GND

10µF

POSITIVE VOLTAGE DOUBLER

C1- OUT

VOLTAGE INVERTER

MAX860

MAX861

C1+

GND

10µF

C1- OUT

________________________________________________________________

SHDN

7 6

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

50mA, Frequency-Selectable, Switched-Capacitor Voltage Converters

ABSOLUTE MAXIMUM RATINGS

Supply Voltage (VDDto GND or GND to OUT)...................+6.0V

Input Voltage Range (LV, FC, –S—H—D—N–) ...................(OUT - 0.3V)

Continuous Output Current (OUT, V

Output Short-Circuit to GND (Note 1)...................................1sec

Continuous Power Dissipation (T

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

µMAX (derate 4.10mW/°C above +70°C) ....................330mW

CERDIP (derate 8.00mW/°C above +70°C).................640mW

Note 1: OUT may be shorted to GND for 1sec without damage, but shorting OUT to VDDmay damage the device and should be

avoided. Also, for temperatures above +85°C, OUT must not be shorted to GND or V damage may result.

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.

MAX860/MAX861

ELECTRICAL CHARACTERISTICS

(Typical Operating Circuit (Inverter), VDD= +5V, –S—H—D—N–= VDD, FC = LV = GND, C1 = C2 = 10µF (Note 2), TA= T otherwise noted. Typical values are at T

Supply Voltage

No-Load Supply Current

) .............................60mA

= +70°C)

= +25°C.)

RL= 1kΩ

MAX860I/E

MAX860M

MAX861I/E

MAX861M

to (V

+ 0.3V)

Operating Temperature Ranges

MAX86_I_A ......................................................-25°C to +85°C

MAX86_ESA.....................................................-40°C to +85°C

MAX86_MJA ..................................................-55°C to +125°C

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

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

, even instantaneously, or device

to T

MIN

CONDITIONS

Inverter, LV = GND Doubler, LV = OUT FC = VDD= 5V FC = VDD= 3V FC = GND FC = OUT FC = V

FC = GND FC = OUT FC = V

FC = GND FC = OUT

1.5 5.5

2.5 5.5

0.2 0.3

0.07

0.6 1.0

1.4 2.5

0.4

1.3

3.3

0.3 0.4

1.1 2.0

2.5 5.0

0.5

2.6

6.5

MAX

, unless

UNITSMIN TYP MAXSYMBOLPARAMETER

VDD= 5V, V

Output Current

Output Resistance (Note 3)

2 _______________________________________________________________________________________

OUT

VDD= 3V, V IL= 50mA

= 10mA, VDD= 2V

more negative than -3.75V

OUT

more negative than -2.5V

OUT

50 100

10 30

12 25 20 35

mAI

Ω

50mA, Frequency-Selectable,

Switched-Capacitor Voltage Converters

ELECTRICAL CHARACTERISTICS (continued)

(Typical Operating Circuit (Inverter), VDD= +5V, –S—H—D—N–= VDD, FC = LV = GND, C1 = C2 = 10µF (Note 2), TA= T otherwise noted. Typical values are at T

Switching Frequency (Note 4)

FC Current (from VDD)

Power Efficiency (Note 5)

= +25°C.)

CONDITIONS

MAX860

MAX861

FC < 4V

MAX860, FC = V

MAX861, FC = V

MAX860/MAX861, FC = VDD, IL= 50mA to GND, C1 = C2 = 68µF

FC = V

FC = GND FC = OUT FC = V

FC = GND FC = OUT

RL= 2kΩ from V to OUT

RL= 1kΩ from OUT to GND

RL= 2kΩ from V to OUT

RL= 1kΩ from OUT to GND

36 30 50 80 130

813 60 100

160 250

93 96

90 93

93 96

88 92

MIN

to T

MAX

MAX860/MAX861

, unless

UNITSMIN TYP MAXSYMBOLPARAMETER

kHz

µA-2 -4I

No load LV = GND

– S—H—D—N–Threshold

Shutdown Supply Current

Note 2: C1 and C2 are low-ESR (<0.2Ω) aluminum electrolytics. Capacitor ESR adds to the circuit’s output resistance. Using Note 3: Specified output resistance includes the effect of the 0.2Ω ESR of the test circuit’s capacitors.

Note 4: The switches are driven directly at the oscillator frequency, without any division. Note 5: At lowest frequencies, using 10µF capacitors gives worse efficiency figures than using the recommended capacitor

capacitors with higher ESR may reduce output voltage and efficiency.

values in Table 3, due to larger 1 ⁄ (f

IH IL

–

S—H—D—N–< 0.3V

No load, V

x C1) term in R

OUT

= -4V µs500Time to Exit Shutdown

OUT

MAX86_I/E MAX86_M

1.2V

0.3V 1

%99 99.9Voltage-Conversion Efficiency

µA

_______________________________________________________________________________________ 3

50mA, Frequency-Selectable, Switched-Capacitor Voltage Converters

__________________________________________Typical Operating Characteristics

(All curves generated using the inverter circuit shown in the wise noted. Test results also valid for doubler mode with LV = OUT and TA= +25°C. All capacitor values used are those recommended in Table 3, unless otherwise noted. The output resistance curves represent the resistance of the device itself, which is ROin the equation for R

shown in the

OUT

Capacitor Selection

OUTPUT VOLTAGE DROP FROM

SUPPLY VOLTAGE vs. LOAD CURRENT

0.8 ALL FREQUENCIES

0.7

0.6

0.5

0.4

DROP (V)

OUT

0.3

MAX860/MAX861

0.2

0.1

VDD = +1.5V

VDD = +5.5V

10 20 50

LOAD CURRENT (mA)

VDD = +2.5V

VDD = +3.5V

VDD = +4.5V, +5.0V

MAX860-01

= +5V)

-2

-4

-6

-8

-10

-12

PERCENTAGE FREQUENCY CHANGE (%)

-14

(FROM FREQUENCY MEASURED WITH V

OUTPUT SOURCE RESISTANCE (RO) vs.

TEMPERATURE

ALL FREQUENCIES

28 24

20 16 12

OUTPUT SOURCE RESISTANCE (Ω)

4 0

-60 -20 40 140

-40 0 60 80 120

VDD = +3V

20 100

TEMPERATURE (°C)

VDD = +1.5V

VDD = +5V

MAX860-04

100

90 80 70 60 50 40

EFFICIENCY (%)

30 20 10

Typical Operating Circuits

section.)

OSCILLATOR FREQUENCY vs.

SUPPLY VOLTAGE

ALL FREQUENCIES, LV CONNECTED TO GND  (INVERTER) OR OUT (DOUBLER)

1.5 2.0 3.0 4.0

1.0

2.5 3.5

SUPPLY VOLTAGE (V)

4.5 5.0 5.5

MAX860

EFFICIENCY vs. LOAD CURRENT

VDD = +1.5V

VDD = +3V

VDD = +5V

INVERTER

FC = V

0.01 1 100

0.1 10 LOAD CURRENT (mA)

with LV = GND and TA= +25°C, unless other-

OUTPUT SOURCE RESISTANCE (RO) vs.

SUPPLY VOLTAGE

20 18

MAX860-02

16 14 12 10

8 6 4

OUTPUT SOURCE RESISTANCE (Ω)

2 0

01 3 5

SUPPLY VOLTAGE (V)

ALL FREQUENCIES

MAX860 SUPPLY CURRENT

vs. SUPPLY VOLTAGE

500

FC = V

MAX860-05

400

300

200

SUPPLY CURRENT (µA)

100

DOUBLER, LV = OUT

INVERTER, LV = GND

> 3V)

123456

SUPPLY VOLTAGE (V)

MAX860-03

MAX860-06

500

400

300

200

SUPPLY CURRENT (µA)

100

MAX861 SUPPLY CURRENT

vs. SUPPLY VOLTAGE

FC = V

DOUBLER, LV = OUT

INVERTER, LV = GND

123456

SUPPLY VOLTAGE (V)

MAX860 OUTPUT CURRENT vs. CAPACITANCE

MAX860-07

40 30

OUTPUT CURRENT (mA)

0.33

HIGH-FREQUENCY MODE

= 130kHz

OSC

FC = OUT LV = GND INVERTER MODE

VIN = +4.5V, V

= -4V

OUT

VIN = +3V, V

1 2.2 22

CAPACITANCE (µF)

OUT

4.7

OUT

= -2.4V

OUT

= -2.7V

MAX860-08

= -3.5V

MAX860 OUTPUT CURRENT vs. CAPACITANCE

MEDIUM-FREQUENCY MODE

= 50kHz

OSC

FC = GND

LV = GND INVERTER MODE

60 50

40 30

OUTPUT CURRENT (mA)

20 10

0.33

1 2.2 22

CAPACITANCE (µF)

4 _______________________________________________________________________________________

VIN = +4.5V, V

VIN = +3V, V

VIN = +4.5V, V

VIN = +3V, V

4.7

OUT

= -3.5V

= -2.4V

OUT

= -2.7V

MAX860-09

= -4V

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