SC310 [SEMTECH]

High-Side Current-Sense Amplifier with Low Impedance Voltage Output; 高边电流检测放大器具有低阻抗电压输出


型号：	SC310
厂家：	SEMTECH CORPORATION
描述：	High-Side Current-Sense Amplifier with Low Impedance Voltage Output 高边电流检测放大器具有低阻抗电压输出放大器
文件：	总12页 (文件大小：845K)
中文：	中文翻译
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SC310

High-Side Current-Sense Amplifier

with Low Impedance Voltage Output

POWER MANAGEMENT

Description

Features

The SC310 is a high-side current sense amplifier ideal for

any application where precision current monitoring is

needed. Possible uses include battery-powered products

such as cellphones and notebooks, as well as industrial

and data acquisition applications. The wide 2.7V to 25V

common mode input range is independent of supply range,

providing complete flexibility in battery sensing applica-

tions.

ꢀ

Three gain versions (20V/V, 50V/V, 100V/V)

available

2.7V to 25V input common mode range

3V to 25V supply voltage range

270 μA supply current

ꢀ

1% typical accuracy

Buffered low impedance voltage output

Industrial temperature range (-40°C to +125°C)

Small, lead-free SOT23-6 Package

The Current-Sense Amplifier offers three gain versions,

SC310A (gain 20 V/V), SC310B (gain 50 V/V) and

SC310C (gain 100 V/V). An external shutdown pin

(SHDN) enables turn off for the IC. A buffered output

with low impedance renders the overall gain immune to

load resistance. Output range is from 0V to Vcc - 1.7V.

Applications

ꢀ

Notebook and Tablet PCs

Data Acquisition

Battery Packs

Charging Applications

Industrial and Embedded Applications

Other features include tiny SOT-23-6 packaging, very low

supply current, and wide supply voltage range (3V to 25V).

The SC310 is rated for operation over the Industrial Tem-

perature range (-40°C to +125°C).

Typical Application Circuit

R_SENSE

I_LOAD

2.7V to 25V

Load/

Battery

3V - 25V

V_OUT

OUT

VCC

0.1uF

June 4, 2007

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SC310

POWER MANAGEMENT

Absolute Maximum Ratings

Exceeding the specifications below may result in permanent damage to the device, or device malfunction. Operation outside of the parameters

specified in the Electrical Characteristics section is not implied.

Parameter

Symbol

VCC

Min

Max

Units

Supply Voltage

-0.3

Differential Input Voltage

Thermal Resistance Junction

Thermal Resistance Junction to Case

V_CS+- V_CS-

θ_JA

0.5

230

°C/W

θ_JC

T_A

Operating Temperature Range

Storage Temperature Range

Junction Temperature Range

Lead Temperature (Soldering) 10s

CS+ Voltage

-40

-65

+125

+150

°C

T_STG

T_J

+150

T_LEAD

V_CS+

V_CS-

V_SHDN

V_ESD

260

-0.3

VCC + 0.3

CS- Voltage

SHDN Voltage

ESD Rating (Human Body Model)

Electrical Characteristics

V_CS+= 2.7V to 25V, V_CC= 3V to 25V, V_SENSE= 0, T_A= T_J= -40°C to +125°C , unless otherwise specified

Parameter

Symbol

V_CC

Conditions

Min

Typ

Max

Units

Operating Voltage Range

Common-Mode Input Range

2.7

V_CMR

0°C ≤ T_A≤ +125°C

-40°C ≤ T_A< 0°C

Common-Mode Rejection

Supply Current

CMR

I_CC

μA

V_CS+> 2.7V, V_CC= 12V

V_CS+> +2.7V

0.27

150

Input Bias Current

I_CS+

I_CS-

V_CS+> +2.7V

Full-Scale Sense Voltage

Total OUT Voltage Error

V_SENSE

V_SENSE= V_CS+- V_CS-

150

4.25

V_SENSE= +100mV, V = 12V,

V_CS+= 12V, -40°C ≤^CT^C_A≤ 85°C

V_SENSE= +100mV, V_CC= 12V,

V_CS+= 12V, T_A= 125°C

4.5

3.25

4.5

V_SENSE= +100mV, V_CC= 12V,

V_CS+= +12V, T_A= +25º

V_SENSE= +100mV, V = 25V,

V_CS+= 25V, -40°C ≤^CT^C_A≤ 85°C

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SC310

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Electrical Characteristics (Cont.)

V_CS+= 2.7V to 25V, V_CC= 3V to 25V, V_SENSE= 0, T_A= T_J= -40°C to +125°C , unless otherwise specified

Parameter

Symbol

Conditions

Min

Typ

Max

4.75

Units

Total OUT Voltage Error

_SENSE= +100mV, V_CC= 25V,

V_CS+= 25V, T_A= 125°C

V_SENSE= +6.25mV, V_CC

+/- 7.5

12V, V_CS+= 12V, -40°C ≤

T_A≤ 125°C

OUT High Voltage

3dB Bandwidth

V_CC- V_OH

-5°C ≤ T_A≤ +125°C

SC310A, V_SENSE= +100mV

SC310B, V_SENSE= +100mV

SC310C, V_SENSE= +100mV

SC310A

1.7

1.4

0.9

MHz

V/V

GAIN

A_V

SC310B

SC310C

100

Gain Accuracy

_SENSE= +100mV,

SC310A/B/C

4.0

OUT Output Resistance ⁽¹⁾

Power-Supply Rejection

R_OUT

V_SENSE= +16mV

PSRR

_SENSE= 16mV

V_CS+> +2.7V

OUT Settling Time to 1% of

the Final Value

V_CC= +12V

V_CS+= +12V

C _LOAD= 5pF

V_SENSE

+6.25mV

μS

+100mV

V_SENSE

+100mV

+6.25mV

Power-Up Time to 1% of the

Final Value

V_SENSE= +100 mV,

_LOAD= 5pF,V_CC= +12V

V_CS+= +12V

μS

(2)

Input bias current for SHDN

V_SHDNThreshold (device on)

V_SHDNThreshold (device off)

Supply Current for SHDN

I_SHDN

V_{SHDN_TH_ON}

V_{SHDN_TH_OFF}

I_CC

V_SHDN= +5V

μA

3V ≤ V_cc≤ 25V

350

V_cc= 12V, V_SHDN= +5V

μA

Note (1): SC310 has a low impedence output. However the maximum output drive capability is limited to 500uA

Note (2): Defined with respect to Shutdown signal. Time taken for output to go high as V_SHDNswitches from 5V to 0V

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SC310

POWER MANAGEMENT

Pin Configuration

Ordering Information

Device ^{(1) (2) (3)}

SC310XSKTRT

SC310XEVB

Package

TOP VIEW

SOT-23-6

Evaluation Board

SHDN

GND

VCC

1 6

OUT

CS-

Notes:

(1) Where X denotes Gain options. Available Gains are:

20 V/V (A), 50 V/V (B), 100 V/V (C). Contact factory for

additional voltage options.

(2) Only available in tape and reel packaging. A reel

contains 3000 devices.

2 5

3 4

CS+

(3) This lead-free device is fully RoHS and WEEE compli-

ant.

(SOT-23 6L)

Pin Descriptions

SC310A, gain = 20 V/V

SC310B, gain = 50 V/V

SC310C, gain = 100 V/V

Name

Function

SHDN

GND

VCC

CS+

CS-

Connect to GND to enable the IC

Ground

Supply Voltage Input, bypass to ground with a 0.1µF capacitor

Power side connection to external sense resistor

Load side connection for the external sense resistor

OUT

Voltage output, V_OUTis proportional to V_SENSE(V_CS+- V_CS-)

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SC310

POWER MANAGEMENT

Electrical Characteristics

V_CS+= 12V, V_CC= 12V, V_SENSE= 100mV, T_A= 25°C, unless otherwise specified

Supply Current

Bias Current v/s

v/s Supply Voltage

Common-Mode Voltage

0.4

0.3

0.2

0.1

150

140

130

120

110

100

SC310C

SC310B

SC310A

SC310B

SC310C

Common-Mode Voltage (V)

Supply Voltage (V)

Total Output Voltage Error

v/s Supply Voltage

Total Output Voltage Error

v/s Common-Mode Voltage

1.00

0.80

0.60

0.40

0.20

0.00

SC310C

SC310A

0.8

0.6

0.4

0.2

SC310B

SC310C

SC310A

Supply Voltage (V)

Common-Mode Voltage (V)

SC310A Gain Accuracy

with Temperature

SC310B Gain Accuracy

with Temperature

1.6

1.4

1.2

-40 deg. C

0.8

0.6

0.4

0.2

Room Temp

-40 deg. C

0.8

0.6

0.4

0.2

Room Temp.

+85 deg. C

Sense Voltage (mV)

120

160

120

160

Sense Voltage (mV)

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SC310

POWER MANAGEMENT

Electrical Characteristics

V_CS+= 12V, V_CC= 12V, V_SENSE= 100mV, T_A= 25°C, unless otherwise specified

SC310C Gain Accuracy

with Temperature

Bias Current v/s

Common-Mode Voltage in Shutdown

V_SHDN= 5V

0.8

0.6

+85 deg. C

0.4

Room Temp.

0.2

-40 deg. C

-0.2

-0.4

-0.6

Common-Mode Voltage (V)

SC310B SC310A SC310C

120

160

Sense Voltage (mV)

Gain v/s Frequency

Supply Current

v/s Supply Voltage in Shutdown

6.00E+01

4.00E+01

2.00E+01

0.00E+00

-2.00E+01

-4.00E+01

V_SHDN= 5V

1.00E+ 1.00E+ 1.00E+ 1.00E+ 1.00E+ 1.00E+ 1.00E+ 1.00E+

01 02 03 04 05 06 07 08

Frequency (Hz)

Supply Voltage (V)

SC310B

SC310A

SC310C

SC310A

SC310C

PSRR v/s Frequency

1.0E+01

-1.0E+01

-3.0E+01

-5.0E+01

-7.0E+01

-9.0E+01

1.0E+0 1.0E+0 1.0E+0 1.0E+0 1.0E+0 1.0E+0 1.0E+0 1.0E+0

Frequency

SC310A

SC310B

SC310C

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SC310

POWER MANAGEMENT

Electrical Characteristics (Cont.)

V_CS+= 12V, V_CC= 12V, V_SENSE= 100mV, T_A= 25°C, unless otherwise specified

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SC310

POWER MANAGEMENT

Block Diagram

VCC

Gain = A1

Gain = A2

Gain = A3

CS+

CS-

Gain = B

⁺B

OUT

GND

20k

10k

SHDN

Disable

Detailed Description

The SC310 has three gain versions as follows:

SC310 is a unidirectional high-side current sense ampli-

fier for precision current monitoring. It has a wide com-

mon-mode range of 2.7 to 25V and allows high-side cur-

rent-sensing at voltages greater than supply voltage (V_CC).

Version

SC310A

SC310B

SC310C

Gain Expression

A1*B

Gain Value

The SC310 operates as follows: Current from source (as

shown in the typical applications circuit on page. 1), flows

through RSENSE to the load. Since the inverting input of

amplifier A has a high input impedance, negligible cur-

rent flows through R5 (neglecting the input bias current).

Amplifier A has an inverting input voltage which equals

V(CS+) - I_LOAD*R_SENSE. The amplifier’s high open-loop gain

forces the non-inverting input voltage to the same volt-

age as the inverting input. The drop across R4 equals

A2*B

A3*B

100

I_LOAD*R_SENSE

Since I_R4flows through R4, IR4 =

(I_LOAD*R_SENSE)/R4. Resistor R3 then sets the overall gain

for amplifier A, A1, A2 or A3 (neglecting the input bias

currents for non-inverting inputs for amplifiers A and B).

The second amplifier, B, is a fixed gain stage (gain = B)

and the final output includes the gain obtained from this

stage.

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SC310

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Application Information

Choosing R_sense

Common Mode Input

Full scale sense voltage for the amplifier is 150mV max. The sense voltage is limited at low values of common mode

The resistor (R_sense) is selected depending on the load of input voltage (V_CMR). The figure below specifies the de-

the system. For light loads a bigger value of R_senseis se- sired sense voltage for low common mode input volt-

lected to minimize the error in the proportional output age. In the figure below we see that SC310A can be op-

voltage. Higher resistor value improves the strength of erated over full-scale sense voltage at Vcs+ = 2.7V,

the signal at the current-sense amplifier input and hence whereas the voltage is limited for SC310B and SC310C.

gives an accurate output.

The voltage at the OUT pin of the amplifier is given as:

V_out= (Gain) * (I_load) * (R_sense

28V

)

Similarly, for heavy loads, a smaller value of R_senseresis-

tor is used not to exceed the max “Sense Voltage” rating

of the IC. Also at high loads, a power rating of R_sensere-

sistor is used and must be acceptable (greater than I²R

power dissipation in the resistor).

SC310C

SC310B

SC310A

3.5V

2.7V

PCB trace can also be used as the sense resistor. This

has the drawback of significant error at the output over

temperature. The trade-off, despite the error in the out-

put voltage, provides for a cost-effective solution.

35mV

70mV

150mV

V_sense

Not drawn to scale

SHDN Function

Layout Guidelines

The SHDN pin should not be kept floating and must be

tied to either ground or be held high. Connecting the pin

to ground is needed for normal operation. The voltage

level at the SHDN pin is independent of the functioning

of the IC.

1. Place the SC310 between the pins and external cir-

cuitry to reduce the trace length.

2. Place the decoupling capacitor at the input (V_CC) as

close as possible to the pin.

3. An R-C filter at the input will help achieve the highest

noise rejection.

Typical Values for Sense Resistors

4. Run the traces from R_SENSEas close as possible. Use

minimum width traces to reduce capacitive coupling.

Table 1. lists the common resistor values for typical op-

eration of the SC310. SC310 is capable of sensing wide

ranges of currents providing proper sense resistors are

used.

Output Impedance

The output impedance of the SC310 is very low. Typical

value is 60Ω. Connecting the OUT pin to a high-imped-

ance input stage is recommended. Resistive loading on

the OUT pin will not affect the gain of the SC310.

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SC310

POWER MANAGEMENT

Table 1. Recommended Component Values

Full-Scale Output Voltage

(Full-Scale V_sense= 100mV)

V_out(V)

Full-Scale Load Current

I _LOAD(A)

Current Sense Resistor R_sense

Gain

(mΩ)

2.0

5.0

0.1

1000

100

10.0

2.0

100

5.0

100

10.0

2.0

5.0

100

10.0

2.0

5.0

100

10.0

2.0

5.0

100

10.0

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SC310

POWER MANAGEMENT

Outline Drawing - SOT-23-6

DIMENSIONS

INCHES MILLIMETERS

DIM

MIN NOM MAX MIN NOM MAX

.057 0.90

.006 0.00

1.45

0.15

.035

A1 .000

A2 .035 .045 .051 .90 1.15 1.30

.010

.003

.020 0.25

.009 0.08

0.50

0.22

2X E/2

.110 .114 .118 2.80 2.90 3.00

E1 .060 .063 .069 1.50 1.60 1.75

.110 BSC

.037 BSC

.075 BSC

2.80 BSC

0.95 BSC

1.90 BSC

ccc C

2X N/2 TIPS

.012 .018 .024 0.30 0.45 0.60

(.024)

(0.60)

0°

10°

0°

10°

aaa

.004

.008

0.10

0.20

bbb

ccc

aaa C

SEATING

PLANE

bxN

bbb

GAGE

PLANE

0.25

C A-B D

(L1)

DETAIL A

^{SEE DETAIL}A

SIDE VIEW

NOTES:

1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES).

2. DATUMS -A- AND -B- TO BE DETERMINED AT DATUM PLANE -H-

3. DIMENSIONS "E1" AND "D" DO NOT INCLUDE MOLD FLASH, PROTRUSIONS

OR GATE BURRS.

Land Pattern - SOT-23-6

DIMENSIONS

DIM

INCHES

(.098)

.055

MILLIMETERS

(2.50)

1.40

0.95

0.60

1.10

3.60

(C)

.037

.024

.043

.141

NOTES:

1. THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY.

CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR

COMPANY'S MANUFACTURING GUIDELINES ARE MET.

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SC310

POWER MANAGEMENT

NOTES

Table 1. Recommended Component Values

Contact Information

Semtech Corporation

Power Management Products Division

200 Flynn Road, Camarillo, CA 93012

Phone: (805) 498-2111 FAX (805)498-3804

Visit us at: www.semtech.com

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SC310 [SEMTECH]

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