TS1105/06 Data Sheet
TS1105 and TS1106 Unidirectional and Bidirectional Current-
Sense Amplifiers + Buffered Unipolar Output with Adjustable Bias
The TS1105 and TS1106 combine the TS1100 or TS1101 current-sense amplifiers with
a unipolar buffered output featuring adjustable bias.
The TS1105 and TS1106 high-side current-sense amplifiers consume 0.68 μA (typ) and
1.2 μA (max) of supply current while the buffered output consumes 0.76 μA (typ) and 1.3
μA (max) of supply current. With an input offset voltage of 100 μV (max) and a gain error
of 0.6% (max), the TS1105 and TS1106 are optimized for high-precision current meas-
urements.
Applications
• Power Management Systems
• Portable/Battery-Powered Systems
• Smart Chargers
• Battery Monitoring
• Overcurrent and Undercurrent Detection
• Remote Sensing
• Industrial Controls
KEY FEATURES
• Low Supply Current
• Current Sense Amplifier: 0.68 μA
• I
VDD
: 0.76 μA
• High-Side Bidirectional and Unidirectional
Buffered Current Sense Amplifiers
• Wide CSA Input Common Mode Range: +2
V to +27 V
• Low CSA Input Offset Voltage: 100 μV
(max)
• Low Gain Error: 0.6% (max)
• Two Gain Options Available:
• Gain = 20 V/V: TS1105-20 and
TS1106-20
• Gain = 200 V/V: TS1105-200 and
TS1106-200
• 8-Pin TDFN Packaging (3 mm x 3 mm)
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TS1105/06 Data Sheet
Ordering Information
1. Ordering Information
Table 1.1. Ordering Part Numbers
Ordering Part Number
1
TS1105-20ITD833
TS1105-200ITD833
TS1106-20ITD833
TS1106-200ITD833
Description
Unidirectional buffered unipolar current sense amplifier
Unidirectional buffered unipolar current sense amplifier
Bidirectional buffered unipolar current sense amplifier
Bidirectional buffered unipolar current sense amplifier
Gain V/V
20
200
20
200
Note:
1. Adding the suffix “T” to the part number (e.g. TS1106-200ITD833T) denotes tape and reel.
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TS1105/06 Data Sheet
System Overview
2. System Overview
2.1 Functional Block Diagrams
Figure 2.1. TS1105 Unidirectional Buffered Current Sense Amplifier Block Diagram
Figure 2.2. TS1106 Bidirectional Buffered Current Sense Amplifier Block Diagram
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TS1105/06 Data Sheet
System Overview
2.2 Current Sense Amplifier + Output Buffer
The internal configuration of the TS1105 unidirectional and TS1106 bidirectional current-sense amplifiers are buffered variations of the
TS1100 unidirectional and TS1101 bidirectional current-sense amplifier respectively. The TS1106 current-sense amplifier is configured
for fully differential input/output operation, therefore the behavior of the TS1106 current-sense amplifier is identical for either V
RS+
>
V
RS–
or V
RS–
> V
RS+
.
Referring to the block diagrams, the inputs of the TS1105/06’s differential input/output amplifier are connected to RS+ and RS– across
an external R
SENSE
resistor that is used to measure current. At the non-inverting input of the current-sense amplifier, the applied volt-
age difference in voltage between RS+ and RS– is I
LOAD
x R
SENSE
. Since the RS– terminal is the non-inverting input of the internal op-
amp, the current-sense op-amp action drives PMOS[1/2] to drive current across R
GAIN[A/B]
to equalize voltage at its inputs.
Thus, since the PMOS source for both M1 and M2 are connected to the inverting input of the internal op-amp and since the voltage
drop across R
GAINA
or R
GAINB
is the same as the external V
SENSE
, the PMOS drain-source current for either M1 or M2 is equal to:
I
DS
(M 1&M 2)
=
or
I
DS
(M 1&M 2)
=
I
LOAD
×
R
SENSE
R
GAIN A
/
B
V
SENSE
R
GAIN A
/
B
The drain terminal for PMOS[1/2] is connected to the transimpedance amplifier’s gain resistor, R
OUT
, via the inverting terminal. The
non-inverting terminal of the transimpedance amplifier is internally connected to VBIAS, therefore the output voltage of the TS1105/06
at the OUT terminal is
R
OUT
V
OUT
=
V
BIAS
−
I
LOAD
×
R
SENSE
×
R
GAIN A
/
B
The current-sense amplifier’s gain accuracy is therefore the ratio match of R
OUT
to R
GAIN[A/B]
. For each of the gain options available,
the table below lists the values for R
GAIN[A/B]
Table 2.1. Internal Gain Setting Resistors (Typical Values)
GAIN (V/V)
20
200
20
200
R
GAIN[A/B]
(Ω)
2k
200
2k
200
R
OUT
(Ω)
40 k
40 k
40 k
40 k
Part Number
TS1105-20
TS1105-200
TS1106-20
TS1106-200
The TS1105/06 allows access to the inverting terminal of the transimpedance amplifier by the FILT pin, whereby a series RC filter may
be connected to reduce noise at the OUT terminal. The recommended RC filter is 4 kΩ and 0.47 μF connected in series from FILT to
GND to suppress the noise. Any capacitance at the OUT terminal should be minimized for stable operation of the buffer.
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TS1105/06 Data Sheet
System Overview
2.3 Sign Output—TS1106 Only
The TS1106’s SIGN output indicates the load current’s direction. The SIGN output is a logic HIGH when M1 is conducting current (VRS
+ > VRS–). Alternatively, the SIGN output is a logic LOW when M2 is conducting current (VRS– > VRS+). The SIGN comparator’s
transfer characteristic is illustrated in the figure below. Unlike other current-sense amplifiers that implement an OUT/SIGN arrangement,
the TS1106 exhibits no “dead zone” at ILOAD switchover
Figure 2.3. TS1106 Sign Output Transfer Characteristic
2.4 Selecting a Sense Resistor
Selecting the optimal value for the external R
SENSE
is based on the following criteria, and commentary follows for each:
1. R
SENSE
Voltage Loss
2. V
OUT
Swing vs. Desired V
SENSE
and Applied Supply Voltage at VDD
3. Total I
LOAD
Accuracy
4. Circuit Efficiency and Power Dissipation
5. R
SENSE
Kelvin Connections
2.4.1 R
SENSE
Voltage Loss
For lowest IR power dissipation in R
SENSE
, the smallest usable resistor value for R
SENSE
should be selected.
2.4.2 V
OUT
Swing vs. Desired V
SENSE
and Applied Supply Voltage at VDD
Although the Current Sense Amplifier draws its power from the voltage at its RS+ and RS– terminals, the signal voltage at the OUT
terminal is provided by a buffer, and is therefore bounded by the buffer’s output range. As shown in the Electrical Characteristics table,
the CSA Buffer has a maximum and minimum output voltage of:
V
OUT
(max )
=
VDD
(min )
− 0.2V
V
OUT
(min )
= 0.2V
Therefore, the full-scale sense voltage should be chosen so that the OUT voltage is neither greater nor less than the maximum and
minimum output voltage defined above. To satisfy this requirement, the full-scale sense voltage, V
SENSE(max)
, should be chosen so
that:
V
SENSE
(max )
<
VBIAS
−
V
OUT
(min )
GAIN
For best performance, R
SENSE
should be chosen so that the full-scale V
SENSE
is less than ±75 mV.
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