Rainbow Electronics MAX711 User Manual

_______________General Description

The MAX710/MAX711 integrate a step-up DC-DC converter with a linear regulator to provide step-up/down voltage conversion. They are optimized for battery applications where the input varies above and below the regulated output voltage. They have an input range from +1.8V to +11V. Typical efficiency when boosting battery inputs is 85%.

The MAX710/MAX711 can be configured for minimum noise or optimum efficiency. Shutdown control turns off the part completely, disconnecting the input from the output (I

SHDN

= 0.2µA). Standby control turns off only the step-up converter and leaves the low-power linear regulator active (IQ= 7µA).

The MAX710 has a preset 3.3V or 5V output voltage. The MAX711 has an adjustable output that can be set from +2.7V to +5.5V with two resistors. Both devices come in 16-pin narrow SO packages.

________________________Applications

Single-Cell, Lithium-Powered Portable Devices Digital Cameras 2- to 4-Cell AA Alkaline Hand-Held Equipment

3.3V and Other Low-Voltage Systems 2-, 3-, and 4-Cell Battery-Powered Equipment Battery-Powered Devices with AC Input Adapters

____________________________Features

♦ Step-Up/Down Voltage Conversion ♦ +1.8V to +11V Input Range ♦ Output:

5V/250mA at V

= 1.8V

5V/500mA at VIN= 3.6V

♦ No External FETs Required ♦ Load Disconnected from Input in Shutdown ♦ Battery Drain:

200µA No-Load (V

= 4V)

7µA in Standby

0.2µA when Off

♦ Low-Noise and High-Efficiency Modes

MAX710/MAX711

3.3V/5V or Adjustable,

Step-Up/Down DC-DC Converters

________________________________________________________________

Maxim Integrated Products

16 15 14 13 12 11 10

1 2 3 4 5 6 7 8

LX LX

PGND GND REF PS LBI+ LBIOUT

TOP VIEW

MAX710 MAX711

PGND

ILIM

3/5 (FB)

SHDN

STBY

N/E

LBO

( ) IS FOR THE MAX711.

__________________Pin Configuration

MAX710

LBI+ LBO

N/E

SHDN

OFF

STBY

3/5

LBI-

REF PGND

0.1µF

GND ILIM

OUTPUT

3.3V/5V

+1.8V TO +11V

INPUT

OUT

3.3V

STBY

__________Typical Operating Circuit

19-1254; Rev 0; 7/97

PART

MAX710C/D

MAX710ESE MAX711C/D

0°C to +70°C

-40°C to +85°C

0°C to +70°C

TEMP. RANGE PIN-PACKAGE

Dice 16 Narrow SO Dice

EVALUATION KIT MANUAL

FOLLOWS DATA SHEET

______________Ordering Information

MAX711ESE -40°C to +85°C 16 Narrow SO

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.

MAX710/MAX711

3.3V/5V or Adjustable, Step-Up/Down DC-DC Converters

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VPS= 5.6V, STBY = PS, C

REF

= 0.1µF, C

OUT

= 4.7µF, TA= -40°C to +85°C, unless otherwise noted. Typical values are at

= +25°C.) (Note 1)

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.

PS, LX, OUT to GND............................................-0.3V to +11.5V

ILIM, SHDN, STBY, FB, 3/5, N/E, LBO,

LBI-, LBI+, REF to GND...........................-0.3V to (V

+ 0.3V)

PGND to GND .......................................................-0.3V to +0.3V

REF Short Circuit to GND...........................................Continuous

OUT

...................................................................................700mA

Continuous Power Dissipation (T

= +70°C)

SO (derate 8.70mW/°C above +70°C)..........................696mW

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

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

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

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

ILIM = GND

ILIM = PS

VLX= 5.6V

MAX711, VPS= 2.7V

MAX710, VPS= 3.7V

STBY

= 0V, linear regulator

VPS= 5.6V

FB = 1.25V

TA= -40°C to +85°C, I

REF

= 0

TA= 0°C to +85°C, I

REF

= 0

MAX711

STBY

= V

SHDN

= logic high, current measured

into PS pin; I

LOAD

= 0

STBY

= 0V

SHDN

= 0V

MAX711, OUT = FB

CONDITIONS

1.1 1.5 1.95

LX Current Limit

0.5 0.8 1.3

µA0.1 1LX Leakage Current

Ω

0.6 1.2

LX On-Resistance 0.3 0.9

0.2 0.6

nA1 50FB Input Current

1.18 1.25 1.31

FB Voltage

V0.9Full Load Start-Up Voltage

1.20 1.25 1.29

mA10Standby Output Current

1.23 1.28 1.32

Reference Voltage

1.24 1.28 1.31

VFB 5.5Output Voltage-Adjustment Range

µA100 140Quiescent Current µA7 16Standby Quiescent Current

µA0.1 5Shutdown Quiescent Current

UNITSMIN TYP MAXPARAMETER

TA= 0°C to +85°C TA= -40°C to +85°C

0mA ≤ I

LOAD

≤ 250mA

MAX711, OUT = FB %0.1 1Load Regulation

3/5 = low, I

OUT

= 0 to 250mA

4.8 5.0 5.2TA= 0°C to +85°C

4.6 5.0 5.3TA= -40°C to +85°C

3/5 = high, I

OUT

= 0 to

250mA, V

= 4.7V

3.17 3.3 3.43TA= 0°C to +85°C

3.05 3.3 3.55TA= -40°C to +85°C

Output Voltage (MAX710)

0 < I

OUT

< 250mA, STBY = PS

%0.5Output Voltage Load Regulation

STBY = PS, 1.8V to 5V

%/V0.3Output Voltage Line Regulation

N/E = GND (Note 2)

N/E = PS

1.8 7.0

1.8 11.0

Input Voltage

MAX710/MAX711

3.3V/5V or Adjustable,

Step-Up/Down DC-DC Converters

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(VPS= 5.6V, STBY = PS, C

REF

= 0.1µF, C

OUT

= 4.7µF, TA= -40°C to +85°C, unless otherwise noted. Typical values are at

= +25°C.) (Note 1)

Note 1: Specifications at -40°C are guaranteed by design, not production tested. Note 2: Guaranteed by design (see Table 1). Note 3: The LBO comparator provides the correct result as long as one input is within the specified input range.

STBY, SHDN, N/E, 3/5, ILIM

STBY = PS

CONDITIONS

V0.4Input Low Voltage

°C150Thermal Shutdown

UNITSMIN TYP MAXPARAMETER

STBY, SHDN, N/E, 3/5, ILIM STBY, SHDN, N/E, 3/5, ILIM

(Note 3) V

LBI-

, V

LBI+

= 1.25V

mV6 40 100Hysteresis

V1.6Input High Voltage

nA1 50Input Bias Current

V1.2 10Input Range LBI-, LBI+

nA1 50Input Bias Current LBI-, LBI+

LBI-

= 1.25V

LBO

= 2mA, V

LBI-

= 1.25V, V

LBI+

= 1V

LBO

= -300µA, V

LBI-

= 1.25V, V

LBI+

= 2V

mV-25 +25LBI/LBO Offset Voltage

0.4 V

VPS- 0.2V

LBO Output Voltage

OUT

= 5.0V

Ω

0.7 1.3

Output PFET Resistance

= 3V, V

OUT

= 0V µA0.4 3Output PFET Leakage

MAX711, V

OUT

= 2.7V 1.6 3.0

MAX710, V

OUT

= 3.0V 1.3 2.4

STBY = PS

°C20Thermal Shutdown Hysteresis

LOGIC

LBI/LBO COMPARATOR

__________________________________________Typical Operating Characteristics

(TA = +25°C, unless otherwise noted.)

MAX710/MAX711

3.3V/5V or Adjustable, Step-Up/Down DC-DC Converters

4 _______________________________________________________________________________________

0.1 10 10001 100

EFFICIENCY vs. LOAD CURRENT—

HIGH-EFFICIENCY AND LOW-NOISE MODES

OUT

= 5V)

MAX710/711 TOC04

LOAD CURRENT (mA)

EFFICIENCY (%)

OUT

= 5V

= 2.5V

N/E = GND

N/E = PS

ILIM = 0.8A

ILIM = 1.5A

0.01 101 10000.1 100

LINEAR-REGULATOR POWER-SUPPLY

REJECTION RATIO vs. FREQUENCY

MAX710/711 TOC08

FREQUENCY (kHz)

PSRR (dB)

0.1 10 10001 100

EFFICIENCY vs. LOAD CURRENT—

HIGH-EFFICIENCY AND LOW-NOISE MODES

OUT

= 3.3V)

MAX710/711 TOC05

LOAD CURRENT (mA)

EFFICIENCY (%)

OUT

= 3.3V

= 2.5V

ILIM = 0.8A

ILIM = 1.5A

LOW-NOISE MODE

HIGH-EFFICIENCY MODE

ILIM = 1.5A

200

600

800

400

1200

1400

1000

1600

0 42 6 8 10 12

NO-LOAD BATTERY CURRENT

vs. INPUT VOLTAGE

MAX710/711 TOC06

INPUT VOLTAGE (V)

SUPPLY CURRENT (µA)

N/E = GND

ILIM = GND (1.5A)

ILIM = PS (0.8A)

0.2

0.6

0.4

0.8

1.0

1 3 4 52 6 87 9 10 11

SHUTDOWN CURRENT

vs. INPUT VOLTAGE

MAX710/711 TOC09

INPUT VOLTAGE (V)

SHUTDOWN CURRENT (µA)

1000

1.0 1.4 2.2 2.6

MAXIMUM OUTPUT CURRENT

vs. INPUT VOLTAGE

100

MAX710/711 TOC07

INPUT VOLTAGE (V)

MAXIMUM OUTPUT CURRENT (mA)

1.81.2 2.01.6 2.4

ILIM = GND

ILIM = PS

N/E = GND N/E = PS

0.1 10 10001 100

EFFICIENCY vs. OUTPUT CURRENT—

HIGH-EFFICIENCY MODE

OUT

= 5V)

MAX710/711 TOC01

OUTPUT CURRENT (mA)

EFFICIENCY (%)

VIN = 1V

OUT

= 5V

N/E = GND

VIN = 3.6V

VIN = 2.5V

VIN = 5.6V

VIN = 1.8V

0.1 10 10001 100

EFFICIENCY vs. OUTPUT CURRENT—

HIGH-EFFICIENCY MODE

OUT

= 3.3V)

MAX710/711 TOC02

OUTPUT CURRENT (mA)

EFFICIENCY (%)

OUT

= 3.3V

N/E = GND

VIN = 2.5V

VIN = 1V

VIN = 1.8V

0.6

0.4

0.2

0.8

1.0

1.2

1.4

1.6

1.8

2.0

0 10050 150 200 250

MINIMUM START-UP INPUT VOLTAGE

vs. LOAD CURRENT

MAX710/711 TOC03

LOAD CURRENT (mA)

INPUT VOLTAGE (V)

OUT

= 5V

N/E = PS

MAX710/MAX711

3.3V/5V or Adjustable,

Step-Up/Down DC-DC Converters

_______________________________________________________________________________________

LINE-TRANSIENT RESPONSE

MAX710/711 TOC10

A: V

OUT

= 3.3V (100mV/div, AC COUPLED), N/E = GND

B: V

= 2V TO 4V, I

OUT

= 100mA

2ms/div

A: V

OUT

= 3.3V (50mV/div, AC COUPLED), N/E = PS

B: I

OUT

= 10mA TO 100mA

LOAD-TRANSIENT RESPONSE

MAX710/711 TOC11

1ms/div

VIN = 2.5V, I

OUT

= 20mA, N/E = GND

OUT

= 5V (20mV/div, AC COUPLED), I

OUT

= 20mA

200µs/div

OUTPUT RIPPLE (HIGH-EFFICIENCY MODE)

MAX710/711 TOC12

VIN = 2.5V, I

OUT

= 20mA, N/E = PS

OUT

= 5V (20mV/div, AC COUPLED), I

OUT

= 20mA

OUTPUT RIPPLE (LOW-NOISE MODE)

MAX710/711 TOC13

200µs/div

A: V

OUT

(2V/div), I

OUT

= 100mA

B: V

SHDN

(2V/div)

START-UP DELAY

MAX710/711 TOC14

20µs/div

A: V

OUT

(2V/div), I

OUT

= 100mA

B: V

SHDN

(2V/div)

TURN-OFF DELAY

MAX710/711 TOC15

200µs/div

____________________________Typical Operating Characteristics (continued)

(TA = +25°C, unless otherwise noted.)

_______________Detailed Description

The MAX710/MAX711 integrate a step-up DC-DC converter with a linear regulator to provide step-up/down voltage conversion. The step-up switch-mode regulator contains an N-channel power MOSFET switch. It also shares a precision voltage reference with a linear regulator that contains a P-channel MOSFET pass element (Figure 1).

Step-Up Operation

A pulse-frequency-modulation (PFM) control scheme with a constant 1µs off-time and variable on-time controls the N-channel MOSFET switch. The N-channel switch turns off when the part reaches the peak current limit or the 4µs maximum on-time. The ripple frequency is a function of load current and input voltage.

Step-Down Operation

The low-dropout linear regulator consists of a reference, an error amplifier, and a P-channel MOSFET. The reference is connected to the error amplifier’s inverting

input. The error amplifier compares this reference with the selected feedback voltage and amplifies the difference. The difference is conditioned and applied to the P-channel pass transistor’s gate.

Operating Configurations

The MAX710/MAX711 have several operating configurations to minimize noise and optimize efficiency for different input voltage ranges. These configurations are accomplished via the N/E input, which controls operation of the on-chip linear regulator.

With N/E low, the linear regulator behaves as a 0.7Ω (at 5V output) PFET switch when the IC is boosting, and as a conventional linear regulator when VIN> V

OUT

. This provides optimum boost efficiency, but the PFET does little to reject boost-converter output ripple. With N/E high, boost ripple rejection is optimized by maintaining headroom (VFV, typically 0.5V at 5V output) across the linear regulator. Boost mode efficiency is then about 10% lower than with N/E high.

MAX710/MAX711

3.3V/5V or Adjustable, Step-Up/Down DC-DC Converters

6 _______________________________________________________________________________________

______________________________________________________________Pin Description

Drain Connection for internal N-channel power MOSFETLX1 Power GroundPGND2

Shutdown Input. When low, the entire circuit is off and OUT is actively pulled to GND.

SHDN

Inductor Current-Limit-Select Input. Connect to GND for 1.5A limit and to PS for 0.8A limit.ILIM3

Standby Input. Connect to GND to disable boost circuit. Connect to PS for normal operation.

STBY

Selects low-noise or high-efficiency mode. Connect to GND for high efficiency and to PS for lowest noise. See

Operating Configurations

section.

N/E

Selects the output voltage. Connect to GND for 5V output and to OUT for 3.3V output.

3/5

—

Low-Battery Comparator OutputLBO8 8

Negative Input to Low-Battery ComparatorLBI-10

Source of internal PFET regulator. The IC is powered from PS.PS12

Positive Input to Low-Battery ComparatorLBI+11

1.28V Reference Voltage Output. Bypass with a 0.1µF capacitor to GND.REF13

Power GroundPGND15

Analog Ground. Must be low impedance. Solder directly to ground plane.GND14

Drain Connection for internal N-channel power MOSFETLX16 16

Linear-Regulator Output. Bypass with a 4.7µF capacitor to GND.OUT9

MAX711MAX710

FUNCTIONNAME

Feedback InputFB— 6

MAX710/MAX711

3.3V/5V or Adjustable,

Step-Up/Down DC-DC Converters

_______________________________________________________________________________________ 7

∆t

FIXED t

OFF

GENERATOR

DRV

N/E

OFF

REF2

REF1

CURRENTLIMIT COMPARATOR

100mV

OUT

ERROR AMP2

ERROR AMP1

REF1

ILIM

PGND

OUT

(FB)

3.3/5

GND

REFB

REFA

LBI-

LBI+

STBY

REF

SHDN

LBO

( ) IS FOR MAX711.

REF2

REF1

MAX710

Figure 1. Functional Diagram

MAX710/MAX711

3.3V/5V or Adjustable, Step-Up/Down DC-DC Converters

8 _______________________________________________________________________________________

MAX710

SHDN LX

STBY

N/E

LBO

LBI+

LBI-

REF

PGND

0.1µF

GND ILIM

OUT

4.7µF

100µF

= +1.8V TO +11V

100µF

3/5

Figure 2a. High-Efficiency Operating Configuration for V

BATT

< V

OUT

Figure 2b. High-Efficiency Operating Configuration for V

BATT

< 6.5V

In high-efficiency mode (N/E = low), the maximum

input voltage is limited to 7V. This voltage limitation is

easily overcome, however, by configuring the LBO output to change modes based on input voltage, allowing an 11V maximum input with high-efficiency configurations. Four operating configurations are described in Table 1 and in the following subsections.

Configuration 1: High Efficiency, 7V Max V

With N/E connected to GND, when the IC boosts, the linear regulator operates only as a switch, with minimum forward drop, until VIN> V

OUT

(where linear regulation begins). This configuration is limited to no more than 7V input, but provides best efficiency for batteryonly operation or low-voltage AC adapter usage.

Configuration 2: High Efficiency, V

BATT

< V

OUT

In this configuration, N/E is driven high by LBO when VIN> V

OUT

(Figure 2a). When VIN< V

OUT

, the IC boosts, and the linear regulator operates as a switch, with minimum forward drop. When VIN> V

OUT

, the linear regulator operates with VFVforward drop, while V

increases by VFVso that OUT maintains regulation. V

is set inside the IC to approximately 0.5V (at 5V V

OUT

When VINis only slightly higher than V

OUT

, conversion efficiency is poorer than in configuration 1, so configuration 2 is most suitable when the battery voltage is less than V

OUT

, but the AC adapter output is greater than

OUT

Up to 11V2

Up to 11V4

Up to 11V3

High efficiency, V

BATT

< V

OUT

(Figure 2a)

Low noise

High efficiency, 11V, V

BATT

< 6.5V

(Figure 2b)

DESCRIPTION

High efficiency, 7V max V

INPUT

VOLTAGE

Up to 7V1

NO.

LBO = N/E LBI- = V

OUT

LBI+ = V

N/E = PS

LBO = N/E LBI- = REF LBI+ = R5, R6

CONNECTIONS

N/E = GND

Table 1. Operating Configurations

= +1.8V TO +11V

100µF

SHDN LX

STBY

N/E

LBO

LBI+

LBI-

REF

MAX710

PGND

0.1µF

OUT

GND ILIM

3/5

4.7µF

REF

= 6.5V

- V

REF

= 1.28V

100µF

)

REF

R5 = R6

V R5 = R6 (4.08)

WHEN V AND V

MAX710/MAX711

3.3V/5V or Adjustable,

Step-Up/Down DC-DC Converters

_______________________________________________________________________________________ 9

Configuration 3: High Efficiency, 11V, V

BATT

< 6.5V

In this configuration, N/E is driven high by LBO when VIN> 6.5V (Figure 2b). When VIN< V

OUT

, the IC boosts, and the linear regulator operates as a switch, with minimum forward drop. When VIN> V

OUT

, linear regulation begins. When VIN> 6.5V (set by R5 and R6), the linear regulator forces a minimum forward drop of VFV(typically 0.5V at 5V V

OUT

) as LBO drives N/E high. This transition is not seen at the output, since the linear regulator already has an input-output voltage difference of 6.5V - 5V. Efficiency with VINslightly higher than V

OUT

is equal to that of configuration 1, so configuration 3 is most suitable when the battery voltage may be near V

OUT

. This hookup has no functional shortcomings compared with configuration 2, except that two additional resistors (R5 and R6) are needed.

Configuration 4: Low Noise

With N/E connected to PS, when the IC is boosting, the linear regulator operates with VFVforward voltage (typically 0.5V at 5V V

OUT

) for optimum noise rejection.

Linear regulation occurs when VIN> V

OUT

+ VFV. The VFVvoltage differential results in boost efficiency typically 10% lower than with the high-efficiency configurations.

ILIM

The current-limit-select input, ILIM, selects between the two peak current limits: 1.5A (ILIM = GND) and 0.8A (ILIM = PS). If the application requires 200mA or less from the MAX710/MAX711, select 0.8A. The lower peak current limit permits the use of smaller, low-cost inductors. The ILIM input is internally diode clamped to GND and PS, and should not be connected to signals outside this range.

Shutdown and Standby Modes

Grounding SHDN turns off the MAX710/MAX711 completely, disconnecting the input from the output. Tie SHDN to PS for normal operation.

The MAX710/MAX711 have a standby mode that shuts down the step-up converter. The linear regulator remains on with a 7µA (typ) LDO quiescent current. Connect STBY to ground to enter standby mode; other- wise, connect STBY to PS.

__________________Design Procedure

Output Voltage Selection

For the MAX710, you can obtain a 3.3V or 5V output voltage by tying 3/5 to GND or PS. Efficiency is typically 85% over a 2mA to 250mA load range. The device is bootstrapped, with power derived from the step-up voltage output (at PS). Under all load conditions, the

MAX710/MAX711 typically start up with a 1V input. If the battery voltage exceeds the programmed output voltage, the output will linear regulate down to the selected output voltage.

The MAX711’s adjustable output voltage is set by two resistors, R1 and R2 (Figure 3), which form a voltage divider between the output and FB. Use the following equation to determine the resistor values:

R1 = R2 [(V

OUT

/ V

REF

) - 1]

where V

REF

= 1.25V.

Since the input bias current at FB has a maximum value of 50nA, R1 and R2 can be large with no significant accuracy loss. Choose R2 in the 100kΩ to 1MΩ range and calculate R1 using the formula above. For 1% error, the current through R1 should be at least 100 times FB’s bias current.

Low-Battery Comparator

The MAX710/MAX711 contain a comparator for lowbattery detection. If the voltage at LBI+ falls below that at LBI- (typically connected to REF), LBO goes low. Hysteresis is typically 50mV. Set the low-battery monitor’s threshold with two resistors, R3 and R4 (Figure 2), using the following equation:

R3 = R4 [(V

LBT

/ V

LBI

-) - 1]

MAX711

SHDN LX

STBY

N/E

LBO

LBI+

LBI-

REF

PGND GND ILIM

OUT

OFF

Figure 3. MAX711 Adjustable Output Voltage

MAX710/MAX711

3.3V/5V or Adjustable, Step-Up/Down DC-DC Converters

10 ______________________________________________________________________________________

where V

LBT

is the desired threshold of the low-battery

detector and V

LBI-

is the voltage applied to the inverting input of the low-battery comparator. Since LBI current is less than 50nA, R3 and R4 can be large (typically 100kΩ to 1MΩ), minimizing input supply loading. If the low-battery comparator is not used, connect LBI+ to PS and LBI- to REF, leaving LBO unconnected.

Inductor Selection

A 22µH inductor value performs well in most MAX710/MAX711 applications. The inductance value is not critical, however, since the MAX710/MAX711 work with inductors in the 18µH to 100µH range. Smaller inductance values typically offer a smaller size for a given series resistance, allowing the smallest overall circuit dimensions. Circuits using larger inductance values exhibit higher output current capability and larger physical dimensions for a given series resistance. The inductor’s incremental saturation current rating should be greater than the peak switch-current limit, which is

1.5A for ILIM = GND and 0.8A for ILIM = PS. However, it is generally acceptable to bias most inductors into saturation by as much as 20%, although this slightly reduces efficiency. The inductor’s DC resistance significantly affects efficiency. See Tables 2 and 3 for a list of suggested inductors and suppliers.

Capacitor Selection

A 100µF, 16V, 0.1Ω equivalent series resistance (ESR), surface-mount tantalum (SMT) output filter capacitor, C2, typically exhibits 50mV output ripple when stepping up from 2V to 5V at 100mA. Smaller capacitors (down to 10µF with higher ESRs) are acceptable for light loads or in applications that can tolerate higher output ripple. The ESR of both bypass and filter capacitors affects efficiency and output ripple. Output voltage ripple is the product of the peak inductor current and the output capacitor’s ESR. Use low-ESR capacitors for best performance, or connect two or more filter capacitors in parallel. Low-ESR, SMT capacitors are currently available from Sprague (595D series) and AVX (TPS series). Sanyo OS-CON organic-semiconductor through-hole capacitors also exhibit very low ESR and are especially

useful for operation at cold temperatures. The output capacitor, C3, needs to be only 4.7µF to maintain linear regulator stability. See Tables 2 and 3 for a list of suggested capacitors and suppliers.

Rectifier Diode

For optimum performance, use a switching Schottky diode. Refer to Tables 2 and 3 for the suggested diode and supplier.

__________Applications Information

The MAX710/MAX711 high-frequency operation makes PC layout important for minimizing ground bounce and noise. Keep the IC’s GND pin and the ground leads of C1 and C2 (Figure 1) less than 0.2in. (5mm) apart. Also keep all connections to the FB and LX pins as short as possible. To maximize output power and efficiency and minimize output ripple voltage, use a ground plane and solder the IC’s GND pin directly to the ground plane.

4.7µF, 16V tantalum capacitor Sprague 595D475X0016A2T

RECTIFIERS (D1)

Schottky diode Motorola MBRS130T3

Coilcraft DO33-08P-223

INDUCTORS (L1)

Sumida CD75-220 (1.5A), CDRH-74-220 (1.23A), or CD54-220

CAPACITORS

100µF, 16V low-ESR tantalum capacitor AVX TPSE107M016R0100 or Sprague 593D107X0016E2W

Table 2. Component Selection

Table 3. Component Suppliers

(803) 626-3123(803) 946-0690

FAX

AVX

SUPPLIER PHONE

(847) 639-1469(847) 639-6400Coilcraft (602) 994-6430(602) 303-5454

(603) 224-1430(603) 224-1961Sprague

Motorola

(847) 956-0702(847) 956-0666Sumida

___________________Chip Information

TRANSISTOR COUNT: 661 SUBSTRATE CONNECTED TO GND

(619) 661-1055(619) 661-6835Sanyo

MAX710/MAX711

3.3V/5V or Adjustable,

Step-Up/Down DC-DC Converters

______________________________________________________________________________________ 11

________________________________________________________Package Information

SOICN.EPS

MAX710/MAX711

3.3V/5V or Adjustable, Step-Up/Down DC-DC Converters

12 ______________________________________________________________________________________

NOTES

Rainbow Electronics MAX711 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual