Maxim MAX472ESA, MAX472CSA, MAX472CPA, MAX471CSA, MAX471CPA Datasheet

...

19-0335; Rev 2; 12/96

Precision, High-Side

Current-Sense Amplifiers

_______________General Description

The MAX471/MAX472 are complete, bidirectional, highside current-sense amplifiers for portable PCs, telephones, and other systems where battery/DC power-line monitoring is critical. High-side power-line monitoring is especially useful in battery-powered systems, since it does not interfere with the ground paths of the battery chargers or monitors often found in “smart” batteries.

The MAX471 has an internal 35mΩ current-sense resistor and measures battery currents up to ±3A. For applications requiring higher current or increased flexibility, the MAX472 functions with external sense and gain-setting resistors. Both devices have a current output that can be converted to a ground-referred voltage with a single resistor, allowing a wide range of battery voltages and currents.

An open-collector SIGN output indicates current-flow direction, so the user can monitor whether a battery is being charged or discharged. Both devices operate from 3V to 36V, draw less than 100µA over temperature, and include a 18µA max shutdown mode.

________________________Applications

Portable PCs:

Notebooks/Subnotebooks/Palmtops Smart Battery Packs Cellular Phones Portable Phones Portable Test/Measurement Systems Battery-Operated Systems Energy Management Systems

____________________________Features

♦ Complete High-Side Current Sensing ♦ Precision Internal Sense Resistor (MAX471) ♦ 2% Accuracy Over Temperature ♦ Monitors Both Charge and Discharge ♦ 3A Sense Capability with Internal Sense Resistor

(MAX471)

♦ Higher Current-Sense Capability with External

Sense Resistor (MAX472)

♦ 100µA Max Supply Current ♦ 18µA Max Shutdown Mode ♦ 3V to 36V Supply Operation ♦ 8-Pin DIP/SO Packages

______________Ordering Information

PART

MAX471CPA

MAX471CSA MAX471EPA -40°C to +85°C MAX471ESA -40°C to +85°C 8 SO MAX472CPA MAX472CSA 0°C to +70°C 8 SO MAX472EPA -40°C to +85°C 8 Plastic DIP MAX472ESA -40°C to +85°C 8 SO

TEMP. RANGE PIN-PACKAGE

0°C to +70°C 0°C to +70°C

0°C to +70°C 8 Plastic DIP

8 Plastic DIP 8 SO 8 Plastic DIP

MAX471/MAX472

__________Typical Operating Circuit

TO

LOAD

LOAD or CHARGER LOGIC

SUPPLY

DISCHARGE/CHARGE

(1V/A)

OUT

RS+ RSRS+

3V TO 36V

MAX471

GNDSHDN

RS-

SIGN

OUT

LOAD

2000

100k



_________________Pin Configurations

TOP VIEW

SHDN

RS+ RS+

1 2

MAX471

3 4



DIP/SO

OUT

RS-

SIGNGND



MAX472 Pin Configuration continued on last page.

________________________________________________________________

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

Maxim Integrated Products

Precision, High-Side Current-Sense Amplifiers

ABSOLUTE MAXIMUM RATINGS

Supply Voltage, RS+, RS-, VCCto GND....................-0.3V, +40V

RMS Current, RS+ to RS- (MAX471 only)..........................±3.3A

Peak Current, (RS+ to RS-) ......................................see Figure 5

Differential Input Voltage, RG1 to RG2 (MAX472 only) .....±0.3V

Voltage at Any Pin Except SIGN

MAX471 only...........................................-0.3V to (RS+ - 0.3V)

MAX472 only ..........................................-0.3V to (V

+ 0.3V)

Voltage at SIGN......................................................-0.3V to +40V

Current into SHDN, GND, OUT, RG1, RG2, V

................±50mA

Current into SIGN.................................................+10mA, -50mA

Note 1: Due to special packaging considerations, MAX471 (DIP, SO) has a higher power dissipation rating than the MAX472. RS+

and RS- must be soldered to large copper traces to achieve this dissipation rating.

MAX471/MAX472

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—MAX471

(RS+ = +3V to +36V, TA= T

Supply Voltage Supply Current Sense Current Sense Resistor

Current-Sense Ratio

No-Load OUT Error

Low-Level OUT Error

SIGN Threshold (I

LOAD

to switch SIGN)

SIGN Sink Current Shutdown Supply Current SHDN Input Low Voltage SHDN Input Low Current SHDN Input High Voltage SHDN Input High Current OUT Output Voltage Range OUT Output Resistance R

OUT Rise, Fall Time tR, t OUT Settling Time to 1%

of Final Value

MIN

required

to T

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

MAX

RS+

= 0A, excludes I

LOAD

= 1A,

LOAD

RS+ = 10V I

= 0A,

LOAD

RS+ LOAD SENSE

OUT

LOAD

RS+ = 10V I

= 30mA,

LOAD

RS+ = 10V 3V ≤ RS+ ≤ 36V, I MAX471C MAX471E

RS+(SHDN)

IH OUT OUTILOAD

V V V

I C

36V

SIGN =

= 0.3V

SIGN

= 2.4V; VCC= 3V to 20V

SHDN

= 0V

SHDN

= 2.4V

SHDN

= 3.0A, V = 50mA to 3.0A, R

LOAD

= 50pF, 10% to 90%

OUT

= 100mA to 3.0A, R

LOAD

= 50pF

OUT

Continuous Power Dissipation (T

= +70°C)

MAX471 (Note 1):

Plastic DIP (derate 17.5mW/°C above +70°C) ..................1.4W

SO (derate 9.9mW/°C above +70°C).............................791mW

MAX472 :

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

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

Operating Temperature Ranges

MAX47_C_A........................................................0°C to +70°C

MAX47_E_A.....................................................-40°C to +85°C

Junction Temperature Range............................-60°C to +150°C

Storage Temperature Range.............................-60°C to +160°C

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

CONDITIONS

336V

SIGN

50 113I

±3I

0.490 0.500 0.510

0.4875 0.500 0.5125

2.5

3.0 ±2.5 ±3.0

LOAD

MAX471C MAX471E MAX471C MAX471E MAX471C MAX471E

= 1A

±4.0 ±6.0

±7.0

- 1.5V

RS+

OUT

= 0V to (V

OUT

- 1.5V) 13 MΩ

RS+

= 2kΩ,

4 µs

15 µs

UNITSMIN TYP MAXSYMBOLPARAMETER

mA/A

µA

RMS

mΩ35 70R

µA

%/V0.1PSRRPower-Supply Rejection Ratio

µA1.0SIGN Output Leakage Current

mA0.1I

µA1.5 18.0I

V0.3V

µA1.0I

V2.4V

µA1.0I

V0V

2 _______________________________________________________________________________________

Precision, High-Side

Current-Sense Amplifiers

ELECTRICAL CHARACTERISTICS—MAX472

(VCC= +3V to +36V, RG1 = RG2 = 200Ω, TA= T

Supply Voltage Supply Current

Input Offset Voltage (Note 2)

Input Bias Current Input Bias-Current Matching

OUT Current Accuracy

RG1

IRG/I

, I

RG2

OUT

No-Load OUT Error

Low-Level OUT Error

SIGN Threshold (V

SENSE

required to switch SIGN)

Shutdown Supply Current SHDN Input Low Voltage SHDN Input Low Current SHDN Input High Voltage SHDN Input High Current OUT Output Voltage Range OUT Output Resistance R

OUT Rise, Fall Time tR, t

OUT Settling Time to 1% of Final Value

Maximum Output Current I

CC(SHDN)

IL IL IH

OUT

OUTIOUT

OUT

to T

MIN

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

MAX

CONDITIONS

= 0A, excludes I

LOAD

MAX472C MAX472E

- I

RG1

GR2

SENSE

= 100mV,

VCC= 10V (Note 3) VCC= 10V,

SENSE

= 0V

VCC= 10V, V

SENSE

= 3mV

3V ≤ VCC≤ 36V, V VCC= 10V V

= 36V

SIGN

= 0.3V

SIGN

= 2.4V; VCC= 3V to 20V

SHDN

= 0V

SHDN

= 2.4V

SHDN

= 1.5mA 13 MΩ

V C

= 5mV to 150mV, R

SENSE

= 50pF, 10% to 90%

OUT

= 5mV to 150mV, R

SENSE

= 50pF

OUT

; VCC= 3V to 20V

SIGN

MAX472C MAX472E ±2.5 MAX472C MAX472E MAX472C MAX472E

= 100mV

SENSE

MAX472C MAX472E

= 2kΩ,

OUT

= 2kΩ,

OUT

1.5 mA

UNITSMIN TYP MAXSYMBOLPARAMETER

µA20 48I 120 140

µV

µA20 35I

µA±0.4 ±3.0I

±2

2.5

3 ±2.5 ±3.0

µA

%/V0.1PSRRPower-Supply Rejection Ratio 60 120 60 140

µV

µA1.0SIGN Output Leakage Current

mA0.1SIGN Output Sink Current

µA1.5 18.0I

µA1.0I

- 1.5V

4 µs

15 µs

MAX471/MAX472

V336V

V0.3V

V2.4V

V0V

Note 2: VOSis defined as the input voltage (V Note 3: V

is the voltage across the sense resistor.

SENSE

_______________________________________________________________________________________ 3

) required to give minimum I

SENSE

OUT

Precision, High-Side Current-Sense Amplifiers

__________________________________________Typical Operating Characteristics

(Typical Operating Circuit (MAX471) or circuit of Figure 4, RG1 = RG2 = 200Ω, R otherwise noted.)

= 2kΩ (MAX472), TA= +25°C, unless

OUT

SUPPLY CURRENT vs.

SUPPLY VOLTAGE

SUPPLY CURRENT (µA)

MAX471/MAX472

TA = +85°C

TA = +25°C

TA = -40°C

21 2415 189123 6 27 30 33 36

(V)

RS+

MAX1471-01

MAX471

NO-LOAD OFFSET CURRENT vs.

SUPPLY VOLTAGE

2.4

2.2

2.0

1.8

1.6

1.4

1.2

OFFSET CURRENT (µA)

1.0

0.8

0.6

TA = -40°C

TA = +25°C

RS+

VS+ = VS-

MAX1471-04

TA = +85°C

21 2415 189123 6 27 30 33 36

(V)

MAX471

RS+ TO RS- RESISTANCE vs.

TEMPERATURE

MAX1471-07

2.5

2.0

1.5

(µA)

SHDN

1.0

0.5

15 12

9 6 3 0

ERROR (%)

-3

-6

-9

-12

-15

0.01 0.10

3.0

2.5

2.0

SHUTDOWN CURRENT vs.

SUPPLY VOLTAGE

TA = -40°C

TA = +25°C

TA = +85°C

21 2415 189123 6 27 30 33 36

(V)

RS+



MAX471

ERROR vs. LOAD CURRENT

FROM RS- TO RS+

LOAD

FROM RS+ TO RS-

LOAD

110

(A)

LOAD

MAX472

NO-LOAD OUTPUT ERROR vs.

SUPPLY VOLTAGE

RG1 = RG2 = 0Ω

TA = +85°C

MAX1471-02

MAX471-05

MAX1471-08

SIGN THRESHOLD (mA)

-1

-2

40 35 30 25 20

PSRR (%)

15 10

1.10

1.00

SIGN THRESHOLD vs.

SUPPLY VOLTAGE

TA = -40°C

TA = +25°C

TA = +85°C

21 2415 189123 6 27 30 33 36

(V)

RS+

MAX471

POWER-SUPPLY REJECTION RATIO

vs. FREQUENCY

= 1A

LOAD



RS+

RS–

V = 0V TO 0.5V

OUT

GND

1µF

V = 0V TO 1V

5Ω

V = 0mV TO 50mV

5 0

0.01 10 1000 POWER-SUPPLY FREQUENCY (kHz)

0.10

1 100



MAX472

ERROR vs. SUPPLY VOLTAGE

= 60mV,

RG1-VRG2

RG1 = RG2 = 200Ω

TA = +85°C

MAX1471-03

MAX471-06

MAX1471-09

RESISTANCE (mΩ)

-40 80

-20 0 60

TEMPERATURE (°C)

(µA) I

OUT

1.5

1.0

0.5

TA = +25°C

TA = -40°C

21 2415 189123 6 27 30 33 36

VCC (V)

0.90

ERROR (%)

0.80

0.70

TA = +25°C

TA = -40°C

4 _______________________________________________________________________________________

21 2415 189123 6 27 30 33 36

(V)

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