SC310CSKTRT Semtech, SC310CSKTRT Datasheet - Page 9

• Manufacturer Part Number: SC310CSKTRT
• Description: IC AMP CURRENT SENSE SOT-23-6
• Manufacturer: Semtech

Specifications of SC310CSKTRT

• Amplifier Type: Current Sense
• Number Of Circuits: 1
• -3db Bandwidth: 900kHz
• Current - Input Bias: 150µA
• Current - Supply: 270µA
• Voltage - Supply, Single/dual (±): 3 V ~ 25 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: SOT-23-6
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Output Type: -
• Current - Output / Channel: -
• Slew Rate: -
• Gain Bandwidth Product: -
• Voltage - Input Offset: -
• Other names: SC310CSKTR

SHDN F
SHDN F
T T T T T ypical V
Output Impedance
Output Impedance
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.
SHDN F
SHDN F
SHDN Function
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.
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
Output Impedance
Output Impedance
The output impedance of the SC310 is very low. Typical
value is 60 . 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.
Choosing R
Choosing R
Choosing R
Choosing R
Choosing R
Full scale sense voltage for the amplifier is 150mV max.
The resistor (R
the system. For light loads a bigger value of R
lected to minimize the error in the proportional output
voltage. Higher resistor value improves the strength of
the signal at the current-sense amplifier input and hence
gives an accurate output.
The voltage at the OUT pin of the amplifier is given as:
Similarly, for heavy loads, a smaller value of R
tor is used not to exceed the max “Sense Voltage” rating
of the IC. Also at high loads, a power rating of R
sistor is used and must be acceptable (greater than I
power dissipation in the resistor).
POWER MANAGEMENT
Application Information
ypical V
ypical V
ypical Values f
ypical V
2005 Semtech Corp.
unction
unction
unction
unction
alues f
alues f
alues for Sense R
alues f
sense
sense
sense
sense
sense
sense
V
out
or Sense R
or Sense R
or Sense R
or Sense Resist
) is selected depending on the load of
= (Gain) * (I
esist
esist
esist
esistor or or or ors s s s s
load
) * (R
sense
)
sense
sense
sense
resis-
is se-
re-
2
R
9
Common Mode Input
Common Mode Input
Common Mode Input
Common Mode Input
Common Mode Input
The sense voltage is limited at low values of common mode
input voltage (V
sired sense voltage for low common mode input volt-
age. In the figure below we see that SC310A can be op-
erated over full-scale sense voltage at Vcs+ = 2.7V,
whereas the voltage is limited for SC310B and SC310C.
Layout Guidelines
Layout Guidelines
Layout Guidelines
Layout Guidelines
Layout Guidelines
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
close as possible to the pin.
3. An R-C filter at the input will help achieve the highest
noise rejection.
4. Run the traces from R
minimum width traces to reduce capacitive coupling.
3.5V
2.7V
28V
5V
0
Not drawn to scale
CMR
35mV
). The figure below specifies the de-
SC310C
SENSE
70mV
V
sense
as close as possible. Use
SC310A
SC310B
www.semtech.com
SC310
150mV
CC
) as