TSC888
Low cost high-side current sense amplifier
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
CC
max = 1 mA
Internally fixed gain: 20 V/V, 50 V/V or 100 V/V
Buffered output
Pin connections
(top view)
L
SOT23-5
(Plastic package)
Applications
■
■
■
■
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Desktop computers and servers SMPS
Photovoltaic/solar systems
Battery chargers
Notebook computers
DC motor control
Gnd 2
Vp 3
4 Vm
Out 1
5 Vcc
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
CC
). The
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
CC
pin to the V
p
pin.
Figure 1.
Application schematics
V
sense
I
load
12V, 5V or
3.3V
line
Main
PWM
controller
5Vsb
Vp
Vm
TSC888
Vcc
Out
Monitoring
device
Stand-by
PWM
controller
Gnd
V
out
=V
sense
.A
v
Table 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.
Symbol
Out
Gnd
Vcc
Vp
Vm
Pin description
Type
Analog output
Power supply
Power supply
Analog input
Analog input
Function
The out voltage is proportional to the magnitude of the sense
voltage V
p
-V
m
.
Ground line.
Positive power supply line.
Connection for the external sense resistor. The measured current
enters the shunt on the V
p
side.
Connection for the external sense resistor. The measured current
exits the shunt on the V
m
side.
2/7
TSC888
Absolute maximum ratings and operating conditions
2
Absolute maximum ratings and operating conditions
Table 2.
Symbol
V
id
V
in
V
CC
V
out
T
stg
T
j
R
thja
ESD
Absolute maximum ratings
Parameter
Input pins differential voltage (V
p
-V
m
)
Input pin voltages (V
p
, V
m
)
(1)
DC supply voltage
(1)
DC output pin voltage
(1)
Storage temperature
Maximum junction temperature
SOT23-5 thermal resistance junction to ambient
Human body model (HBM)
(2)
Machine model (MM)
(3)
Value
±2
-0.3 to 30
-0.3 to 25
-0.3 to Vcc
-55 to 150
150
250
1
100
Unit
V
V
V
V
°C
°C
°C/W
kV
V
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.
Symbol
V
CC
T
oper
V
icm
Operating conditions
Parameter
DC supply voltage from T
min
to T
max
Operational temperature range (T
min
to T
max
)
Common mode operating range
Value
4.0 to 24
-40 to 85
2.8 to 24
Unit
V
°C
V
3/7
Electrical characteristics
TSC888
3
Electrical characteristics
The electrical characteristics given in the following tables are measured under the following
test conditions unless otherwise specified:
T
amb
=25°C, V
cc
=5V, V
sense
=V
p
-V
m
=50mV, V
m
=12V, no load on Out
Table 4.
Symbol
I
CC
Supply
Parameter
Total supply current
Test conditions
V
sense
= 0
Min.
Typ.
Max.
1
Unit
mA
Table 5.
Symbol
Input
Parameter
DC common mode rejection
Variation of V
out
versus V
icm
referred to input
Supply voltage rejection
Variation of V
out
versus V
cc
referred to input
Input leakage current
Input bias current
Test conditions
2.8V< V
icm
< 24V
V
sense
= 30mV
4.0V< V
CC
< 24V
V
sense
= 30mV
V
cc
=0V
V
sense
=0V
5.5
Min.
Typ.
Max.
Unit
CMR
95
dB
SVR
I
lk
I
ib
95
1
8
dB
µA
µA
Table 6.
Symbol
Av
ΔV
out
I
sc
Output
Parameter
Gain
Total output voltage accuracy
Short-circuit current
Output stage high-state saturation
voltage
V
OH
=V
CC
-V
out
Output stage low-state saturation
voltage
OUT connected to V
CC
or
GND
V
sense
=1V
I
out
=1mA
V
sense
=-1V
I
out
=1mA
2
Test conditions
TSC888A
TSC888B
TSC888C
Min.
Typ.
20
50
100
±6
Max.
Unit
V/V
%
mA
V
OH
0.8
1
V
V
OL
50
100
mV
4/7
TSC888
Package information
4
Package information
In order to meet environmental requirements, STMicroelectronics offers these devices in
ECOPACK
®
packages. These packages have a lead-free second level interconnect. The
category of second level interconnect is marked on the package and on the inner box label,
in compliance with JEDEC Standard JESD97. The maximum ratings related to soldering
conditions are also marked on the inner box label. ECOPACK is an STMicroelectronics
trademark. ECOPACK specifications are available at:
www.st.com.
Figure 2.
SOT23-5 package mechanical drawing
Table 7.
SOT23-5 package mechanical data
Dimensions
Ref.
Min.
A
A1
A2
b
C
D
E
E1
e
e1
L
0.35
0.90
0.00
0.90
0.35
0.09
2.80
2.60
1.50
Millimeters
Typ.
Max.
1.45
0.15
1.30
0.50
0.20
3.00
3.00
1.75
0.95
1.9
0.55
13.7
Min.
35.4
0.00
35.4
13.7
3.5
110.2
102.3
59.0
Mils
Typ.
Max.
57.1
5.9
51.2
19.7
7.8
118.1
118.1
68.8
37.4
74.8
21.6
5/7
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