lt6109-1 Linear Technology Corporation, lt6109-1 Datasheet - Page 10
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lt6109-1
Manufacturer Part Number
lt6109-1
Description
High Side Current Sense Amplifer With Reference And Comparators
Manufacturer
Linear Technology Corporation
Datasheet
1.LT6109-1.pdf
(28 pages)
LT6109-1/LT6109-2
BLOCK DIAGRAMS
APPLICATIONS INFORMATION
The LT6109 high side current sense amplifier provides
accurate monitoring of currents through an external sense
resistor. The sensed voltage is amplified by an external
resistor-set gain and level shifted from the positive power
supply to a ground-referred output.
The LT6109 comparators have a threshold set with a built-in
400mV precision reference and have 10mV of hysteresis.
The open-drain outputs can be easily used to level shift
to digital supplies.
10
10
1
2
3
4
LT6109-2
SENSEHI
SENSELO
EN/RST
OUTC2
OUTC1
Figure 2. LT6109-2 Block Diagram (Comparators with the Same Polarity)
V
–
3k
3k
V
+
OVERCURRENT FLAG
200nA
OVERCURRENT FLAG
RESET
RESET TIMING
ENABLE AND
–
+
9
Amplifier Theory of Operation
An internal sense amplifier loop forces SENSEHI to have
the same potential as SENSELO. Connecting an external
resistor, R
V
R
R
the sense amplifier do not load this current, so it will flow
through an internal MOSFET to the output pin, OUTA.
V
+
V
SENSE
SENSE
IN
–
, will flow through R
V
V
V
5
, across R
. A corresponding current, I
+
–
+
V
–
34V
IN
–
+
+
–
, between SENSEHI and V
REFERENCE
IN
V
–
6V
400mV
that is the voltage appearing across
100
IN
. The high impedance inputs of
OUTA
INC2
INC1
610912 F02
V
V
+
–
8
7
6
OUTA
+
forces a potential,
, equal to V
SENSE
610912f
/