TS1101
PIN FUNCTIONS
PIN
1
2
3
4
5
6
LABEL
GND
SIGN
OUT
RS-
VDD
RS+
FUNCTION
Ground. Connect this pin to analog ground.
Comparator Output, push-pull; SIGN is HIGH for (V
RS+
> V
RS-
) and LOW for (V
RS-
> V
RS+
).
Output Voltage. V
OUT
is proportional to V
SENSE
= (V
RS+
- V
RS-
) or (V
RS-
- V
RS+
).
External Sense Resistor Load-Side Connection
SIGN Comparator External Power Supply Pin; Connect this pin to system’s logic VDD supply.
External Sense Resistor Power-Side Connection
BLOCK DIAGRAM
DESCRIPTION OF OPERATION
The internal configuration of the TS1101 – a
bidirectional high-side, current-sense amplifier – is a
variation of the TS1100 uni-directional current-sense
amplifier. In the design of the TS1101, the input
amplifier was reconfigured for fully differential
input/output operation and a second low-threshold p-
channel FET (M2) was added where the drain
terminal of M2 is also connected to ROUT.
Therefore, the behavior of the TS1101 for when
V
RS-
> V
RS+
is identical for when V
RS+
> V
RS-
.
Referring to the typical application circuit on Page 1,
the inputs of the TS1101’s differential input/output
amplifier are connected across an external RSENSE
TS1101DS r1p0
resistor that is used to measure current. At the non-
inverting input of the TS1101 (the RS- terminal), the
applied voltage is I
LOAD
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
(I
LOAD
x RSENSE). Therefore, the voltage drop
across RSENSE (V
SENSE
= V
RS+
- V
RS-
) and the
voltage drop across RGAINA (at the RS+ terminal)
are equal. Necessary for gain ratio match, both
RGAINA and RGAINB are the same value.
Since p-channel M1’s source is connected to the
inverting input of the internal op amp and since the
voltage drop across RGAINA is the same as the
Page 7
RTFDS
TOUCHSTONE [ TOUCHSTONE SEMICONDUCTOR INC ]
