Datasheet MAX860ISA+ Datasheet (FREI)

Page 1

19-0239; Rev 3; 8/13

MAX860/MAX861

50mA, Frequency-Selectable,

Switched-Capacitor Voltage Converters

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.

_______________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

____________________________Features

o 8-Pin, 1.11mm High µMAX Package

o Invert or Double the Input Supply Voltage

o Three Selectable Switching Frequencies

o High Frequency Reduces Capacitor Size

o 87% Efficiency at 50mA

o 200µA Quiescent Current (MAX860)

o 1µA Shutdown Supply Current

o 600mV Voltage Drop at 50mA Load

o 12Ω Output Resistance

______________Ordering Information

__________________Pin Configuration

PART TEMP RANGE PIN-PACKAGE

MAX860ISA -25°C to +85°C 8 SO

MAX860IUA -25°C to +85°C 8 µMAX

MAX860C/D 0°C to +70°C Dice*

MAX860ESA -40°C to +85°C 8 SO

MAX860MJA -55°C to +125°C 8 CERDIP†

-55°C to +125°C 8 SO

MAX861ISA -25°C to +85°C 8 SO

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 8 CERDIP†

__________Typical Operating Circuit

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

†

Contact factory for availability.

µMAX is a registered trademark of Maxim Integrated Products, Inc.

MAX860MSA/PR3

MAX860

MAX861

C1+

GND

10μF

INPUT

VOLTAGE

+2.5V TO +5.5V

C1- OUT

VOLTAGE INVERTER

MAX860

MAX861

C1+

GND

10μF

C1- OUT

POSITIVE VOLTAGE DOUBLER

SHDN

INPUT VOLTAGE +1.5V TO +5.5V

INVERTED NEGATIVE OUTPUT

10μF

DOUBLED POSITIVE OUTPUT

10μF

TOP VIEW

C1+

GND

C1-

MAX860

MAX861

SO/μMAX

SHDN

OUT

Page 2

MAX860/MAX861 50mA, Frequency-Selectable,

Switched-Capacitor Voltage Converters

Maxim Integrated

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

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

MIN

to T

MAX

, unless

otherwise noted. Typical values are at T

= +25°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.

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

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

to (V

+ 0.3V)

Continuous Output Current (OUT, V

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

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

Continuous Power Dissipation (T

= +70°C)

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

µMAX (derate 4.2mW/°C above +70°C) ......................362mW

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

Operating Temperature Ranges

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

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

MAX86_M_A ..................................................-55°C to +125°C

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

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

Soldering Temperature (reflow) .......................................+240°C

= 10mA, VDD= 2V

RL= 1kΩ

IL= 50mA

VDD= 3V, V

OUT

more negative than -2.5V

VDD= 5V, V

OUT

more negative than -3.75V

MAX861M

MAX860M

MAX861I/E

MAX860I/E

CONDITIONS

20 35

OUT

Output Resistance (Note 4)

12 25

mAI

OUT

Output Current

50 100

6.5

No-Load Supply Current (Note 3)

2.6

0.5

2.5 5.0

1.1 2.0

2.5 5.5

Supply Voltage

1.5 5.5

0.3 0.4

3.3

1.3

0.4

0.2 0.3

0.07

0.6 1.0

1.4 2.5

UNITSMIN TYP MAXSYMBOLPARAMETER

Inverter, LV = GND

Doubler, LV = OUT

FC = VDD= 5V

FC = OUT

FC = GND

FC = VDD= 3V

FC = V

FC = OUT

FC = GND

FC = V

FC = OUT

FC = GND

FC = V

FC = OUT

FC = GND

10 30

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

, even instantaneously, or device

damage may result.

Page 3

MAX860/MAX861

50mA, Frequency-Selectable,

Switched-Capacitor Voltage Converters

Maxim Integrated

ELECTRICAL CHARACTERISTICS (continued)

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

MIN

to T

MAX

, unless

otherwise noted. Typical values are at T

= +25°C.)

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

capacitors with higher ESR may reduce output voltage and efficiency.

Note 3: MAX860/MAX861 may draw high supply current during startup, up to the minimum operating supply voltage. To guaran-

tee proper startup, the input supply must be capable of delivering 90mA more than the maximum load current.

Note 4: Specified output resistance includes the effect of the 0.2Ω ESR of the test circuit’s capacitors. Note 5: The switches are driven directly at the oscillator frequency, without any division. Note 6: At lowest frequencies, using 10µF capacitors gives worse efficiency figures than using the recommended capacitor

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

x C1) term in R

OUT

– S—H—D—N–< 0.3V

MAX860

LV = GND

No load

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

MAX860, FC = V

MAX861, FC = V

MAX861

FC < 4V

CONDITIONS

µA

Shutdown Supply Current

0.3V

– S—H—D—N–Threshold

1.2V

%99 99.9Voltage-Conversion Efficiency

Power Efficiency (Note 6)

88 92

93 96

80 130

30 50

90 93

93 96

813

60 100

kHz

160 250

Switching Frequency (Note 5)

µA-2 -4I

FC Current (from VDD)

UNITSMIN TYP MAXSYMBOLPARAMETER

No load, V

OUT

= -4V µs500Time to Exit Shutdown

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

MAX86_I/E

MAX86_M

Page 4

MAX860/MAX861 50mA, Frequency-Selectable,

Switched-Capacitor Voltage Converters

Maxim Integrated

__________________________________________Typical Operating Characteristics

(All curves generated using the inverter circuit shown in the

Typical Operating Circuits

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

wise noted. Test results also valid for doubler mode with LV = OUT and T

= +25°C. All capacitor values used are those recom-

mended in Table 3, unless otherwise noted. The output resistance curves represent the resistance of the device itself, which is R

the equation for R

OUT

shown in the

Capacitor Selection

section.)

0.33

MAX860 OUTPUT CURRENT vs. CAPACITANC

MEDIUM-FREQUENCY MODE

MAX860-09

CAPACITANCE (μF)

OUTPUT CURRENT (mA)

4.7

1 2.2 22

VIN = +4.5V, V

OUT

= -3.5V

VIN = +3V, V

OUT

= -2.4V

VIN = +4.5V, V

OUT

= -4V

VIN = +3V, V

OUT

= -2.7V

OSC

= 50kHz FC = GND LV = GND INVERTER MODE

OUTPUT VOLTAGE DROP FROM

SUPPLY VOLTAGE vs. LOAD CURRENT

0.8

0.7

0.6

0.5

0.4

DROP (V)

OUT

0.3

0.2

0.1

ALL FREQUENCIES

VDD = +1.5V

VDD = +4.5V, +5.0V

VDD = +5.5V

10 20 50

LOAD CURRENT (mA)

VDD = +2.5V

VDD = +3.5V

MAX860-01

= +5V)

-2

-4

-6

-8

-10

-12

PERCENTAGE FREQUENCY CHANGE (%)

(FROM FREQUENCY MEASURED WITH V

-14

OUTPUT SOURCE RESISTANCE (RO) vs.

TEMPERATURE

MAX860-04

100

EFFICIENCY (%)

ALL FREQUENCIES

OUTPUT SOURCE RESISTANCE (Ω)

-60 -20 40 140

-40 0 60 80 120

VDD = +3V

20 100

TEMPERATURE (°C)

VDD = +1.5V

VDD = +5V

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)

OUTPUT SOURCE RESISTANCE (RO) vs.

SUPPLY VOLTAGE

MAX860-02

OUTPUT SOURCE RESISTANCE (Ω)

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)

123 456

SUPPLY VOLTAGE (V)

MAX860-03

MAX860-06

MAX861 SUPPLY CURRENT

vs. SUPPLY VOLTAGE

500

FC = V

400

300

SUPPLY CURRENT (μA)

200

100

INVERTER, LV = GND

123 456

SUPPLY VOLTAGE (V)

DOUBLER, LV = OUT

MAX860-07

OUTPUT CURRENT (mA)

MAX860 OUTPUT CURRENT vs. CAPACITANCE

HIGH-FREQUENCY MODE

= 130kHz

OSC

FC = OUT LV = GND INVERTER MODE

VIN = +4.5V, V

0.33

VIN = +4.5V, V

= -4V

OUT

VIN = +3V, V

1 2.2 22

CAPACITANCE (μF)

= -3.5V

OUT

= -2.4V

OUT

= -2.7V

OUT

4.7

MAX860-08

Page 5

MAX860/MAX861

50mA, Frequency-Selectable,

Switched-Capacitor Voltage Converters

Maxim Integrated

______________________________________________________________Pin Description

____________________________Typical Operating Characteristics (continued)

(All curves generated using the inverter circuit shown in the

Typical Operating Circuits

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

wise noted. Test results also valid for doubler mode with LV = OUT and T

= +25°C. All capacitor values used are those recom-

mended in Table 3, unless otherwise noted. The output resistance curves represent the resistance of the device itself, which is R

the equation for R

OUT

shown in the

Capacitor Selection

section.)

INVERTER

DOUBLER

Doubled Positive Output

Flying-Capacitor Negative Terminal

Ground

Low-Voltage-Operation Input. Connect to OUT.

Active-Low Shutdown Input. Connect to GND pin if not used. Connect to OUT to disable the charge pump.

Positive Input Supply

Flying-Capacitor Positive Terminal

Frequency Control, see Table 1

FUNCTION

Positive Input SupplyV

Flying-Capacitor Negative TerminalC1-4

Negative OutputOUT5

Low-Voltage-Operation Input. Connect to GND.LV6

Active-Low Shutdown Input. Connect to VDDif not used. Connect to GND to disable the charge pump.

– S—H—D—N

–

GroundGND3

Flying-Capacitor Positive Terminal C1+2

Frequency Control, see Table 1FC1

NAMEPIN

MAX861

OUTPUT CURRENT vs. CAPACITANCE

HIGH-FREQUENCY MODE

= 250kHz

OSC

FC = OUT LV = GND

INVERTER MODE

OUTPUT CURRENT (mA)

VIN = +4.5V, V

VIN = +3V, V

0.33

1 2.2 22

CAPACITANCE (μF)

= -4V

OUT

VIN = +3V, V

= -2.7V

OUT

VIN = +4.5V,

= -3.5V

OUT

= -2.4V

OUT

4.7

MAX860-10

MAX861

OUTPUT CURRENT vs. CAPACITANCE

MEDIUM-FREQUENCY MODE

= 100kHz

OSC

FC = GND

LV = GND INVERTER MODE

OUTPUT CURRENT (mA)

0.33

VIN = +3V,

= -2.4V

OUT

VIN = +3V, V

1 2.2 22

CAPACITANCE (μF)

VIN = +4.5V, V

OUT

VIN = +4.5V, V

OUT

= -2.7V

OUT

4.7

= -3.5V

MAX860-11

= -4V

Page 6

MAX860/MAX861 50mA, Frequency-Selectable,

Switched-Capacitor Voltage Converters

Maxim Integrated

_______________Detailed Description

The MAX860/MAX861 capacitive charge pumps either invert or double the voltage applied to their inputs. For highest performance, use low equivalent series resistance (ESR) capacitors. See the

Capacitor Selection

section for more details. The frequency-control (FC) pin allows you to choose one of three switching frequencies; these three selectable frequencies are different for each device. When shut down, MAX860/MAX861 current consumption reduces to less than 1µA.

Common Applications

Voltage Inverter

The most common application for these devices is a charge-pump voltage inverter (see

Typical Operating

Circuits

). This application requires only two external components—capacitors C1 and C2—plus a bypass capacitor if necessary (see

Bypass Capacitor

section). Refer to the

Capacitor Selection

section for suggested capacitor types

and values.

Even though the MAX860/MAX861’s output is not actively regulated, it is fairly insensitive to load-current changes. A circuit output source resistance of 12Ω (calculated using the formula given in the

Capacitor Selection

section) means that, with a +5V input, the output voltage is -5V under no load and decreases to -4.4V with a 50mA load. The MAX860/MAX861 output source resistance (used to calculate the circuit output source resistance) vs. temperature and supply voltage are shown in the

Typical

Operating Characteristics

graphs.

Calculate the output ripple voltage using the formula given in the

Capacitor Selection

section.

Positive Voltage Doubler

The MAX860/MAX861 can also operate as positive voltage doublers (see

Typical Operating Circuits

). This application requires only two external components, capacitors C1 and C2. The no-load output is twice the input voltage. The electrical specifications in the doubler mode are very similar to those of the inverter mode except for the Supply Voltage Range (see

Electrical

Characteristics

table) and No-Load Supply Current (see

graph in

Typical Operating Characteristics

). The circuit output source resistance and output ripple voltage are calculated using the formulas in the

Capacitor Selection

section.

Active-Low Shutdown Input

When driven low, the –S—H—D—N–input shuts down the device. In inverter mode, connect –S—H—D—N–to VDDif it is not used. In doubler mode, connect –S—H—D—N–to GND if it

is not used. When the device is shut down, all active circuitry is turned off.

In the inverting configuration, loads connected from OUT to GND are not powered in shutdown mode. However, a reverse-current path exists through two diodes between OUT and GND; therefore, loads connected from V

to OUT draw current from the input

supply.

In the doubling configuration, loads connected from the VDDpin to the GND pin are not powered in shutdown mode. Loads connected from the VDDpin to the OUT pin draw current from the input supply through a path similar to that of the inverting configuration (described above).

Frequency Control

Charge-pump frequency for both devices can be set to one of three values. Each device has a unique set of three available frequencies, as indicated in Table 1. The oscillator and charge-pump frequencies are the same (i.e., the charge-pump frequency is not half the oscillator frequency, as it is on the MAX660, MAX665, and ICL7660).

*See the Electrical Characteristics for detailed switchingfrequency specifications.

A higher switching frequency minimizes capacitor size for the same performance and increases the supply current (Table 2). The lowest fundamental frequency of the switching noise is equal to the minimum specified switching frequency (e.g., 3kHz for the MAX860 with FC open). The spectrum of noise frequencies extends above this value because of harmonics in the switching waveform. To get best noise performance, choose the device and FC connection to select a minimum switching frequency that lies above your sensitive bandwidth.

Low-Voltage-Operation Input

LV should be connected to GND for inverting operation. To enhance compatibility with the MAX660, MAX665, and ICL7660, you may float LV if the input voltage exceeds 3V. In doubling mode, LV must be connected to OUT for all input voltages.

FREQUENCY (kHz)

FC CONNECTION

MAX860 MAX861

FC = VDDor open 6 13

FC = GND 50 100

FC = OUT 130 250

Table 1. Nominal Switching Frequencies*

Page 7

MAX860/MAX861

50mA, Frequency-Selectable,

Switched-Capacitor Voltage Converters

Maxim Integrated

__________Applications Information

Capacitor Selection

The MAX860/MAX861 are tested using 10µF capacitors for both C1 and C2, although smaller or larger values can be used (Table 3). Smaller C1 values increase the output resistance; larger values reduce the output resistance. Above a certain point, increasing the capacitance of C1 has a negligible effect (because the output resistance becomes dominated by the internal switch resistance and the capacitor ESR). Low-ESR capacitors provide the lowest output resistance and ripple voltage. The output resistance of the entire circuit (inverter or doubler) is approximately:

OUT

= RO+ 4 x ESRC1+ ESRC2+ 1 / (fSx C1)

where RO(the effective resistance of the MAX860/ MAX861’s internal switches) is approximately 8Ω and f

is the switching frequency. R

OUT

is typically 12Ω when using capacitors with 0.2Ω ESR and fS, C1, and C2 values suggested in Table 3. When C1 and C2 are so large (or the switching frequency is so high) that the internal switch resistance dominates the output resistance, estimate the output resistance as follows:

OUT

= RO+ 4 x ESRC1+ ESR

A typical design procedure is as follows:

1) Choose C1 and C2 to be the same, for convenience.

2) Select fS:

a) If you want to avoid a specific noise frequency,

choose f

appropriately.

b) If you want to minimize capacitor cost and size,

choose a high f

c) If you want to minimize current consumption,

choose a low fS.

3) Choose a capacitor based on Table 3, although higher or lower values can be used to optimize performance. Table 4 lists manufacturers who provide low-ESR capacitors.

*In addition to Table 3, four graphs in the

Typical

Operating Characteristics

section show typical output

current for C1 and C2 capacitances ranging from

0.33µF to 22µF. Output current is plotted for inputs of

4.5V (5V - 10%) and 3.0V (3.3V - 10%), and also for

10% and 20% output droop from the ideal -VINvalue.

ATTRIBUTE

LOWER

FREQUENCY

HIGHER

FREQUENCY

Output Ripple Larger Smaller

C1, C2 Values Larger Smaller

Supply Current Smaller Larger

C1, C2 (μF)NOMINAL FREQUENCY (kHz)

6 68

13 47

50 10

100 4.7

130 4.7

250 2.2

Table 2. Switching-Frequency Trade-Offs

Table 3. Suggested Capacitor Values*

Table 4. Low-ESR Capacitor Manufacturers

MANUFACTURER–Series PHONE FAX COMMENTS

AVX TPS Series (803) 946-0629 (803) 626-3123 Low-ESR tantalum, SMT

AVX TAG Series (803) 946-0629 (803) 626-3123 Low-cost tantalum, SMT

Matsuo 267 Series (714) 969-2491 (714) 960-6492 Low-cost tantalum, SMT

Sprague 595 Series (603) 224-1961 (613) 224-1430 Low-ESR tantalum, SMT

Sanyo MV-GX Series (619) 661-6835 (619) 661-1055 Aluminum electrolytic, through hole

Sanyo CV-GX Series (619) 661-6835 (619) 661-1055 Aluminum electrolytic, SMT

Nichicon PL Series (847) 843-7500 (847) 843-2798 Aluminum electrolytic, through hole

United Chemicon (Marcon) (847) 696-2000 (847) 696-9278 Ceramic SMT

TDK (847) 390-4461 (847) 390-4405 Ceramic SMT

Page 8

MAX860/MAX861 50mA, Frequency-Selectable,

Switched-Capacitor Voltage Converters

Maxim Integrated

Figure 2. Paralleling MAX860s or MAX861s to Reduce Output Resistance

Figure 1. Cascading MAX860s or MAX861s to Increase Output Voltage

Flying Capacitor, C1

Increasing the size of the flying capacitor reduces the output resistance.

Output Capacitor, C2

Increasing the size of the output capacitor reduces the output ripple voltage. Decreasing its ESR reduces both output resistance and ripple. Smaller capacitance values can be used if one of the higher switching frequencies is selected, if less than the maximum rated output current (50mA) is required, or if higher ripple can be tolerated. The following equation for peak-to-peak ripple applies to both the inverter and doubler circuits.

OUT

RIPPLE

= ———————— + 2 x I

OUT

x ESR

2 x fSx C2

Bypass Capacitor

Bypass the incoming supply to reduce its AC impedance and the impact of the MAX860/MAX861’s switching noise. The recommended bypassing depends on the circuit configuration and where the load is connected.

When the inverter is loaded from OUT to GND or the doubler is loaded from VDDto GND, current from the supply switches between 2 x I

OUT

and zero. Therefore, use a large bypass capacitor (e.g., equal to the value of C1) if the supply has a high AC impedance.

When the inverter and doubler are loaded from VDDto OUT, the circuit draws 2 x I

OUT

constantly, except for short switching spikes. A 0.1µF bypass capacitor is sufficient.

Cascading Devices

Two devices can be cascaded to produce an even larger negative voltage, as shown in Figure 1. The

unloaded output voltage is nominally -2 x V

, but this is reduced slightly by the output resistance of the first device multiplied by the quiescent current of the second. The output resistance of the complete circuit is approximately

five times

the output resistance of a sin-

gle MAX860/MAX861.

Three or more devices can be cascaded in this way, but output resistance rises dramatically, and a better solution is offered by inductive switching regulators (such as the MAX755, MAX759, MAX764, or MAX774). Connect LV as with a standard inverter circuit (see

Description

The maximum load current and startup current of nth cascaded circuit must not exceed the maximum output current capability of (n-1)th circuit to ensure proper startup.

Paralleling Devices

Paralleling multiple MAX860s or MAX861s reduces the output resistance. As illustrated in Figure 2, each device requires its own pump capacitor (C1), but the reservoir capacitor (C2) serves all devices. C2’s value should be increased by a factor of n, where n is the number of devices. Figure 2 shows the equation for calculating output resistance. An alternative solution is to use the MAX660 or MAX665, which are capable of supplying up to 100mA of load current. Connect LV as with a standard inverter circuit (see

Pin Description

Combined Doubler/Inverter

In the circuit of Figure 3, capacitors C1 and C2 form the inverter, while C3 and C4 form the doubler. C1 and C3 are the pump capacitors; C2 and C4 are the reservoir capacitors. Because both the inverter and doubler use part of the charge-pump circuit, loading either output causes both outputs to decline towards GND. Make

…

MAX860 MAX861

“1”

445

MAX860 MAX861

“n”

…

= -nV

OUT

OF SINGLE DEVICE

OUT

NUMBER OF DEVICES

…

MAX860 MAX861

OUT

“1”

445

C1C1

MAX860 MAX861

“n”

…

OUT

= -V

OUT

Page 9

MAX860/MAX861

50mA, Frequency-Selectable,

Switched-Capacitor Voltage Converters

Table 5. Product Selection Guide

MAX860 MAX861

D1, D2 = 1N4148

= -V

OUT

PART

NUMBER

MAX660 100 6.5 5/40

MAX665 100 6.5 5/40

OUTPUT

CURRENT

(mA)

OUTPUT

RESISTANCE

(Ω)

SWITCHING

FREQUENCY

(kHz)

Figure 3. Combined Doubler and Inverter

= (2VIN) -

OUT

) - (V

FD2

)

FD1

sure the sum of the currents drawn from the two outputs does not exceed 60mA. Connect LV as with a standard inverter circuit (see

Pin Description

Compatibility with

MAX660/MAX665/ICL7660

The MAX860/MAX861 can be used in sockets designed for the MAX660, MAX665, and ICL7660 with a minimum of one wiring change. This section gives advice on installing a MAX860/MAX861 into a socket designed for one of the earlier devices.

The MAX660, MAX665, and ICL7660 have an OSC pin instead of –S—H—D—N–. MAX660, MAX665, and ICL7660 normal operation is with OSC floating (although OSC can be overdriven). If OSC is floating, pin 7 (–S—H—D—N–) should be jumpered to VDDto enable the MAX860/MAX861 permanently. Do not leave –S—H—D—N–on the MAX860/ MAX861 floating.

The MAX860/MAX861 operate with FC either floating or connected to VDD, OUT, or GND; each connection defines the oscillator frequency. Thus, any of the normal MAX660, MAX665, or ICL7660 connections to pin 1 will work with the MAX860/MAX861, without modifications. Changes to the FC connection are only required if you want to adjust the operating frequency.

MAX860 50 12 6/50/130

MAX861 50 12 13/100/250

ICL7660 10 55 5

___________________Chip Topography

C1+

GND

C1-

0.058"

(1.47mm)

PROCESS: BiCMOS

SUBSTRATE CONNECTED TO V

0.084"

(2.13mm)

SHDN

OUT

Maxim Integrated

Page 10

MAX860/MAX861 50mA, Frequency-Selectable,

Switched-Capacitor Voltage Converters

Maxim Integrated

Package Information

For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status.

PACKAGE TYPE PACKAGE CODE OUTLINE NO.

LAND

PATTERN NO.

8 SO S8-4

21-0041

90-0096

8 CDIP J8-2

21-0045 —

8 µMAX U8-1

21-0036 90-0092

Page 11

Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.

Maxim Integrated 160 Rio Robles, San Jose, CA 95134 USA 1-408-601-1000 ________________________________

MAX860/MAX861

50mA, Frequency-Selectable,

Switched-Capacitor Voltage Converters

Revision History

REVISION

NUMBER

0 7/94 Initial release —

2 4/03 Updated Electrical Characteristics and Cascading Devices section. 3, 8

3 8/13

REVISION

DATE

DESCRIPTION

Added MAX860MSA/PR3 to data sheet and revised Absolute Maximum Ratings.

PAGES

CHANGED

1, 2