LTC6102CDD LINER [Linear Technology], LTC6102CDD Datasheet - Page 13

• Manufacturer Part Number: LTC6102CDD
• Description: Precision Zero Drift Current Sense Amplifi er
• Manufacturer: LINER [Linear Technology]

APPLICATIONS INFORMATION
The LTC6102HV can be used at voltages up to 105V. This
additional voltage requires that more power be dissipated
for a given level of current. This will further limit the allowed
output current at high ambient temperatures.
It is important to note that the LTC6102 has been designed
to provide at least 1mA to the output when required, and
can deliver more depending on the conditions. Care must
be taken to limit the maximum output current by proper
choice of sense and input resistors and, if input fault
conditions are likely, an external clamp.
Output Filtering
The output voltage, V
makes fi ltering straightforward. Any circuit may be used
which generates the required Z
response. For example, a capacitor in parallel with R
will give a low pass response. This will reduce unwanted
noise from the output, and may also be useful as a charge
reservoir to keep the output steady while driving a switch-
ing circuit such as a mux or ADC. This output capacitor
in parallel with an output resistor will create a pole in the
output response at:
Useful Equations
Input Voltage: V
Current Gain:
Transconductance:
Transimpedance:
f
Voltage Gain:
–3dB
=
2 • • R
I
V
SENSE
I
OUT
SENSE
V
OUT
SENSE
1
OUT
I
SENSE
V
OUT
• C
OUT
V
=
I
SENSE
=I
OUT
, is simply I
=
OUT
R
SENSE
R
SENSE
R
R
= R
OUT
OUT
IN
IN
=
SENSE
R
• R
to get the desired fi lter
1
IN
SENSE
•
OUT
R
R
OUT
IN
• Z
OUT
. This
OUT
Input Sense Range
The inputs of the LTC6102 can function from V
Not only does this allow a wide V
the input reference to be separate from the positive supply
(Figure 5). Note that the difference between V
must be no more than the input sense voltage range listed
in the Electrical Characteristics table.
Monitoring Voltages Above V
The LTC6102 may be confi gured to monitor voltages that are
higher than its supply, provided that the negative terminal
of the input voltage is within the input sense range of the
LTC6102. Figure 6 illustrates a circuit in which the LTC6102
has its supply pin tied to the lower potential terminal of the
sense resistor instead of the higher potential terminal. The
operation of the LTC6102 is such that the –INS and –INF
pins will servo to within a few microvolts of +IN, which is
shorted to V
includes V
across R
causing current V
the supply current of the LTC6102 is also monitored, as
it fl ows through R
Figure 5. V
R
SENSE
(V
+
– 2V) TO V
LOAD
SENSE
V
BAT
+
, the circuit will operate properly. The voltage
+
. Since the input sense range of the LTC6102
+
LTC6102/LTC6102HV
R
Powered Separately from Load Supply (V
+
IN
will be held across R
+IN
V
SENSE
SENSE
–
LTC6102
/R
.
+
IN
to fl ow to R
+
–
SENSE
and Level Translation
IN
range, it also allows
V
OUT
–INS
–INF
V
REG
6102 F05
+
by the LTC6102,
OUT
. In this case,
+
R
to (V
OUT
BAT
V
0.1μF
+
V
OUT
+
13
and V
BAT
– 2V).
6102fb
)
+