TS1102
PIN FUNCTIONS
PIN
SOT23
LABEL
FUNCTION
5
4
1, 2
3
RS+
RS-
GND
OUT
External Sense Resistor Power-Side Connection
External Sense Resistor Load-Side Connection
Ground. Connect these pins to analog ground.
Output Voltage. VOUT is proportional to VSENSE = VRS+ - VRS-
BLOCK DIAGRAM
DESCRIPTION OF OPERATION
The internal configuration of the TS1102 – a
unidirectional high-side, current-sense amplifier - is
based on a commonly-used operational amplifier (op
amp) circuit for measuring load currents (in one
direction) in the presence of high-common-mode
voltages. In the general case, a current-sense
amplifier monitors the voltage caused by a load
current through an external sense resistor and
generates an output voltage as a function of that load
current. Referring to the typical application circuit on
Page 1, the inputs of the op-amp-based circuit are
connected across an external RSENSE resistor that
is used to measure load current. At the non-inverting
input of the TS1102 (the RS+ terminal), the applied
voltage is ILOAD x RSENSE. Since the RS- terminal is
the non-inverting input of the internal op amp, op-amp
feedback action forces the inverting input of the
internal
op
amp
to
the
same
potential
(ILOAD x RSENSE). Therefore, the voltage drop across
RSENSE (VSENSE) and the voltage drop across RGAIN
(at the RS+ terminal) are equal. To minimize any
additional error because of op-amp input bias current
mismatch, both RGAINs are the same value.
Since the internal p-channel FET’s source is
connected to the inverting input of the internal op
amp and since the voltage drop across RGAIN is the
same as the external VSENSE, op amp feedback action
drives the gate of the FET such that the FET’s drain-
source current is equal to:
VSEꢃSE
ꢀꢁS
ꢂ
RꢄAꢀꢃ
TS1102DS r1p0
Page 7
RTFDS
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