ST TSC888 User Manual

Low cost high-side current sense amplifier

pOut

Features

■ Independent supply and input common-mode

voltages

■ Wide common-mode operating range: 2.8 V to

24 V

■ Wide supply voltage range: 4 to 24 V

■ Low current consumption: I

■ Internally fixed gain: 20 V/V, 50 V/V or 100 V/V

■ Buffered output

Applications

■ Desktop computers and servers SMPS

■ Photovoltaic/solar systems

■ Battery chargers

■ Notebook computers

■ DC motor control

max = 1 mA

CC

Gnd

SOT23-5

(Plastic package)

Pin connections

(top view)

1

2

3V

TSC888

L

5

Vcc

4

Vm

Description

The TSC888 measures a small differential voltage
on a high-side shunt resistor and translates it into
a ground-referenced output voltage. The gain is
internally fixed.

Wide input common-mode voltage range, low
quiescent current, and tiny SOT23-5 packaging
make the TSC888 ideal for use in a wide variety
of applications.

Input common-mode and power supply voltages
are independent. Common-mode voltage can
range from 2.8 V to 24 V in operating conditions.

Current consumption lower than 1 mA and wide
supply voltage range allow to connect the power
supply to either side of the current measurement
shunt with minimal error.

June 2008 Rev 1 1/7

www.st.com

7

Application schematics and pin description TSC888

1 Application schematics and pin description

The TSC888 high-side current-sense amplifier features a 2.8 V to 24 V input common-mode
range that is independent of supply voltage. The main advantage of this feature is to allow
high-side current sensing at voltages much greater than the supply voltage (V
TSC888 can therefore be supplied by a 5 Vsb line and monitor a 3.3 V, 5 V or 12 V power
line. Considering the wide supply voltage operating range (4 V to 24 V) another option
available in most cases is to connect the V

pin to the Vp pin.

CC

Figure 1. Application schematics

V

sense

I

load

12V, 5V or 3.3V line

Main

PWM

controller

5Vsb

Vp

Vcc

Vm

TSC888

Out

). The

CC

Monitoring

device

Stand-by

PWM

controller

Gnd

V

out=Vsense.Av

Tab l e 1 describes the function of each pin. Their position is shown in the illustration on the

cover page and in Figure 1 above.

Table 1. Pin description

Symbol Type Function

Out Analog output

Gnd Power supply Ground line.

Vcc Power supply Positive power supply line.

Vp Analog input

Vm Analog input

The out voltage is proportional to the magnitude of the sense
voltage V

p-Vm

.

Connection for the external sense resistor. The measured current
enters the shunt on the V

side.

p

Connection for the external sense resistor. The measured current
exits the shunt on the V

side.

m

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TSC888 Absolute maximum ratings and operating conditions

2 Absolute maximum ratings and operating conditions

Table 2. Absolute maximum ratings

Symbol Parameter Value Unit

V

id

V

in

V

CC

V

out

T

stg

T

R

thja

ESD

1. Voltage values are measured with respect to the Gnd pin.

2. Human body model: 100 pF discharged through a 1.5kΩ resistor between two pins of the device, done for
all couples of pin combinations with other pins floating.

3. Machine model: a 200 pF cap is charged to the specified voltage, then discharged directly between two
pins of the device with no external series resistor (internal resistor < 5 Ω), done for all couples of pin
combinations with other pins floating.

Table 3. Operating conditions

Input pins differential voltage (Vp-Vm)±2V

(1)

(1)

-0.3 to 30 V

-0.3 to 25 V

-0.3 to Vcc V

Input pin voltages (Vp, Vm)

DC supply voltage

(1)

DC output pin voltage

Storage temperature -55 to 150 °C

Maximum junction temperature 150 °C

j

SOT23-5 thermal resistance junction to ambient 250 °C/W

(3)

(2)

1kV

100 V

Human body model (HBM)

Machine model (MM)

Symbol Parameter Value Unit

V

T

V

CC

oper

icm

DC supply voltage from T

Operational temperature range (T

min

to T

max

min

to T

4.0 to 24 V

) -40 to 85 °C

max

Common mode operating range 2.8 to 24 V

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