STMICROELECTRONICS TSM1051

TSM1051
CONSTANT VOLTAGE AND CONSTANT CURRENT
CONTROLLER FOR BATTERY CHARGERS AND ADAPTORS
■ CONSTANT VOLTAGE AND CONSTANT
■
■
■
■
■
■
CURRENT CONTROL
LOW VOLTAGE OPERATION
PRECISION INTERNAL VOLTAGE
REFERENCE
LOW EXTERNAL COMPONENT COUNT
CURRENT SINK OUTPUT STAGE
EASY COMPENSATION
LOW AC MAINS VOLTAGE REJECTION
ORDER CODE
Part Number
Temperature
Range
TSM1051CLT
TSM1051CD
0 to 85°C
0 to 85°C
Package
Marking
L
D
•
•
M801
M1051C
L = Tiny Package (SOT23-6) - only available in Tape & Reel (LT)
D = Small Outline Package (SO) - also available in Tape & Reel (DT)
DESCRIPTION
TSM1051 is a highly integrated solution for SMPS
applications requiring CV (constant voltage) and
CC (constant current) mode.
TSM1051 integrates one voltage reference, two
operational amplifiers (with ORed outputs common collectors), and a current sensing circuit.
The voltage reference combined with one
operational amplifier makes it an ideal voltage
controller, and the other low voltage reference
combined with the other operational amplifier
makes it an ideal current limiter for output low side
current sensing.
The current threshold is fixed, and precise.
The only external components are:
* a resistor bridge to be connected to the output of
the power supply (adapter, battery charger) to set
the voltage regulation by dividing the desired
output voltage to match the internal voltage
reference value.
* a sense resistor having a value and allowable
dissipation power which need to be chosen
according to the internal voltage threshold.
* optional compensation components (R and C).
TSM1051, housed in one of the smallest package
available, is ideal for space shrinked applications
such as adapters and battery chargers.
L
SOT23-6
(Plastic Package)
D
SO8
(Plastic Micro package)
PIN CONNECTIONS (top view)
SOT23-6
SO8
1
Vctrl
Vcc
6
1
Vctrl
Gnd
8
2
Gnd
Vsense
5
2
Vcc
Out
7
3
Out
Ictrl
4
3
Vsense
Ictrl
6
4
Nc
Nc
5
APPLICATIONS
■ ADAPTERS
■ BATTERY CHARGERS
January 2002
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TSM1051
PIN DESCRIPTION
SOT23-6 Pinout
Name
Pin #
Vcc
Gnd
Vctrl
Ictrl
Out
Vsense
6
2
1
4
3
5
Type
Power Supply
Power Supply
Analog Input
Analog Input
Current Sink Output
Analog Input
Function
Positive Power Supply Line
Ground Line. 0V Reference For All Voltages
Input Pin of the Voltage Control Loop
Input Pin of the Current Control Loop
Output Pin. Sinking Current Only
Input Pin of the Current Control Loop
SO8 Pinout
Name
Pin #
Vcc
Gnd
Vctrl
Ictrl
Out
Vsense
NC
NC
2
8
1
6
7
3
5
4
Type
Power Supply
Power Supply
Analog Input
Analog Input
Current Sink Output
Analog Input
Function
Positive Power Supply Line
Ground Line. 0V Reference For All Voltages
Input Pin of the Voltage Control Loop
Input Pin of the Current Control Loop
Output Pin. Sinking Current Only
Input Pin of the Current Control Loop
ABSOLUTE MAXIMUM RATINGS
Symbol
Vcc
Vi
Top
Tj
Rthja
Rthja
2/9
DC Supply Voltage
DC Supply Voltage
Input Voltage
Operating Free Air Temperature Range
Maximum Junction Temperature
Thermal Resistance Junction to Ambient SO8 package
Thermal Resistance Junction to Ambient SOT23-6 package
Value
Unit
14
-0.3 to Vcc
0 to 85
150
130
250
V
V
°C
°C
°C/W
°C/W
TSM1051
OPERATING CONDITIONS
Symbol
Vcc
Parameter
DC Supply Conditions
Value
Unit
2.5 to 12
V
ELECTRICAL CHARACTERISTICS
Tamb = 25°C and Vcc = +5V (unless otherwise specified)
Symbol
Parameter
Test Condition
Min
Typ
Max
Unit
1.1
1.2
2
mA
Total Current Consumption
Icc
Total Supply Current - not taking the
output sinking current into account
Tamb
0 < Tamb < 85°C
Voltage Control Loop
Gmv
Transconduction Gain (Vctrl). Sink
Current Only 1)
Tamb
0 < Tamb < 85°C
1
3.5
2.5
Vref
Voltage Control Loop Reference 2)
1.198
1.186
1.21
Iibv
Input Bias Current (Vctrl)
Tamb
0 < Tamb < 85°C
Tamb
0 < Tamb < 85°C
mA/mV
1.222
1.234
V
50
100
nA
mA/mV
Current Control Loop
Gmi
Transconduction Gain (Ictrl). Sink
Current Only 3)
Tamb
0 < Tamb < 85°C
1.5
7
Vsense
Current Control Loop Reference 4)
196
192
200
Iibi
Current out of pin ICTRL at -200mV
Iout = 2.5mA Tamb
0 < Tamb < 85°C
Tamb
0 < Tamb < 85°C
204
208
mV
25
50
µA
200
mV
Output Stage
Vol
Ios
Low output voltage at 10 mA sinking
current
Output Short Circuit Current. Output to
Vcc. Sink Current Only
Tamb
0 < Tamb < 85°C
Tamb
0 < Tamb < 85°C
27
35
50
mA
1. If the voltage on VCTRL (the negative input of the amplifier) is higher than the positive amplifier input (Vref=1.210V), and it is increased
by 1mV, the sinking current at the output OUT will be increased by 3.5mA.
2. The internal Voltage Reference is set at 1.210V (bandgap reference). The voltage control loop precision takes into account the cumulative
effects of the internal voltage reference deviation as well as the input offset voltage of the trans-conductance operational amplifier. The
internal Voltage Reference is fixed by bandgap, and trimmed to 0.5% accuracy at room temperature.
3. When the positive input at ICTRL is lower than -200mV, and the voltage is decreased by 1mV, the sinking current at the output OUT will
be increased by 7mA.
4. The internal current sense threshold is set to -200mV. The current control loop precision takes into account the cumulative effects of the
internal voltage reference deviation as well as the input offset voltage of the trans-conduction operational amplifier.
3/9
TSM1051
Figure 1 : Internal Schematic
Vcc
1.210V
Out
+
+
-
200mV
Gnd
Ictrl
Vsense
Figure 2 : Typical Adapter or Battery Charger Application Using TSM1051
D
To primary
TSM1051
Vcc
R2
Rout
Rvc1
+
-
Cvc2
22pF
470K
IL
Cvc1
2.2nF
Load
Out
1.210V
200mV
OUT+
Cic1
2.2nF
+
+
Gnd
+
Ictrl
Ric1
22K
R1
Vsense
Ric2
500
Vsense
Rsense
OUT-
IL
In the above application schematic, the TSM1051 is used on the secondary side of a flyback adapter (or
battery charger) to provide an accurate control of voltage and current. The above feedback loop is made
with an optocoupler.
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TSM1051
Figure 6 : Vsense vs Ambient Temperature
Figure 3 : Vref vs Ambient Temperature
1,230
203,5
203,0
1,225
2,5V ≤ Vcc ≤ 12V
Vsense (V)
Vref (V)
1,220
1,215
1,210
Vcc=5V
202,5
Vcc=2,5V
202,0
201,5
Vcc=12V
201,0
1,205
200,5
1,200
0
0
20
40
60
80
100
Ta ambient temperature (°C)
Figure 4 : Vsense pin input bias current vs
Ambient Temperature
60
80
100
120
Figure 7 : Ictrl pin input bias current vs
Ambient Temperature
30
100
28
V cc=12V
Vcc=2,5V
26
Iibi ( A)
Iibv (nA)
40
Ta ambient temperature (°C)
120
80
20
120
60
V cc=5V
40
24
Vcc=12V
22
20
V cc=2,5V
20
0
0
20
40
60
80
100
Victrl=200mV
18
120
0
Ta ambient temperature (°C )
Figure 5 : Output short circuit current vs
Ambient Temperature
Vcc=5V
20
40
60
80
100
Ta ambient temperature (°C)
120
Figure 8 : Supply current vs Ambient
Temperature
60
1,6
Vcc=12V
1,4
50
Icc (mA)
Ios (mA)
Vcc=5V
30
Vcc=5V
1,2
Vcc=12V
40
1,0
Vcc=2,5V
0,8
0,6
20
Vcc=2,5V
0,4
10
0,2
0,0
0
0
20
40
60
80
100
Ta ambient temperature (°C)
120
0
20
40
60
80
100
Ta ambient temperature (°C)
120
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TSM1051
PRINCIPLE OF OPERATION AND APPLICATION HINTS
1.1. Voltage Control
The voltage loop is controlled via a first transconductance operational amplifier, the resistor bridge
R1, R2, and the optocoupler which is directly connected to the output.
The relation between the values of R1 and R2
should be chosen as written in Equation 1.
R1 = R2 x Vref / (Vout - Vref)
Eq1
Where Vout is the desired output voltage.
To avoid the discharge of the load, the resistor
bridge R1, R2 should be highly resistive. For this
type of application, a total value of 100KΩ (or
more) would be appropriate for the resistors R1
and R2.
As an example, with R2 = 100KΩ, Vout = 4.10V,
Vref = 1.210V, then R1 = 41.9KΩ.
Note that if the low drop diode should be inserted
between the load and the voltage regulation resistor bridge to avoid current flowing from the load
through the resistor bridge, this drop should be
taken into account in the above calculations by replacing Vout by (Vout + Vdrop).
Vsense threshold is achieved internally by a resistor bridge tied to the Vref voltage reference. Its
middle point is tied to the positive input of the current control operational amplifier, and its foot is to
be connected to lower potential point of the sense
resistor as shown on the following figure. The resistors of this bridge are matched to provide the
best precision possible.
The current sinking outputs of the two trans-conductance operational amplifiers are common (to
the output of the IC). This makes an ORing function which ensures that whenever the current or
the voltage reaches too high values, the optocoupler is activated.
The relation between the controlled current and
the controlled output voltage can be described
with a square characteristic as shown in the following V/I output-power graph.
Figure 9 : Output voltage versus output current
Vout
Voltage regulation
Current regulation
1. Voltage and Current Control
1.2. Current Control
The current loop is controlled via the second
trans-conductance operational amplifier, the
sense resistor Rsense, and the optocoupler.
The control equation verifies:
Rsense x Ilim = Vsense
eq2
Rsense = Vsense / Ilim
eq2’
where Ilim is the desired limited current, and
Vsense is the threshold voltage for the current
control loop.
As an example, with Ilim = 1A, Vsense = -200mV,
then Rsense = 200mΩ.
Note that the Rsense resistor should be chosen
taking into account the maximum dissipation
(Plim) through it during full load operation.
Plim = Vsense x Ilim.
eq3
As an example, with Ilim = 1A, and Vsense =
200mV, Plim = 200mW.
Therefore, for most adapter and battery charger
applications, a quarter-watt, or half-watt resistor to
make the current sensing function is sufficient.
0
TSM1051 Vcc : independent power supply
Secondary current regulation
Iout
TSM1051 Vcc : On power output
Primary current regulation
2. Compensation
The voltage-control trans-conductance operational amplifier can be fully compensated. Both of its
output and negative input are directly accessible
for external compensation components.
An example of a suitable compensation network is
shown in Fig.2. It consists of a capacitor
Cvc1=2.2nF and a resistor Rcv1=470KΩ in series,
6/9
TSM1051
connected in parallel with another capacitor
Cvc2=22pF.
The current-control trans-conductance operational amplifier can be fully compensated. Both of its
output and negative input are directly accessible
for external compensation components.
An example of a suitable compensation network is
shown in Fig.2. It consists of a capacitor
Cic1=2.2nF and a resistor Ric1=22KΩ in series.
When the Vcc voltage reaches 12V it could be interesting to limit the current coming through the
output in the aim to reduce the dissipation of the
device and increase the stability performances of
the whole application.
An example of a suitable Rout value could be
330Ω in series with the opto-coupler in case
Vcc=12V.
3. Start Up and Short Circuit Conditions
Under start-up or short-circuit conditions the
TSM1051 is not provided with a high enough supply voltage. This is due to the fact that the chip has
its power supply line in common with the power
supply line of the system.
Therefore, the current limitation can only be ensured by the primary PWM module, which should
be chosen accordingly.
If the primary current limitation is considered not to
be precise enough for the application, then a sufficient supply for the TSM1051 has to be ensured
under any condition. It would then be necessary
to add some circuitry to supply the chip with a separate power line. This can be achieved in numerous ways, including an additional winding on the
transformer.
The following schematic shows how to realize a
low-cost power supply for the TSM1051 (with no
additional windings).
Please pay attention to the fact that in the particular case presented here, this low-cost power supply can reach voltages as high as twice the voltage of the regulated line. Since the Absolute Maximum Rating of the TSM1051 supply voltage is 14
V, this low-cost auxiliary power supply can only be
used in applications where the regulated line voltage does not exceed 7 V.
Figure 10 :
Vcc
D
OUT+
To primary
R2
TSM105
Vcc
Rout
Rvc1
+
-
Cvc2
22pF
470K
Cvc1
2.2nF
Load
Out
1.210V
Rs
IL
DS
200mV
Cic1
2.2nF
+
+
Gnd
CS
+
+
Ictrl
Ric1
22K
R1
Vsense
Ric2
500
Vsense
Rsense
7/9
OUT-
IL
TSM1051
PACKAGE MECHANICAL DATA
6 PINS - PLASTIC PACKAGE SOT23-6
Millimeters
Inches
Dimensions
Min.
A
A1
A2
B
c
D
E
e
H
L
θ
Typ.
0.9
0
0.9
0.35
0.09
2.8
1.5
Max.
Min.
1.45
0.15
1.3
0.5
0.2
3
1.75
0.035
0
0.035
0.0137
0.004
0.11
0.059
3
0.6
10 deg.
0.102
0.004
0
0.95
2.6
0.1
0
Typ.
Max.
0.057
0.006
0.0512
0.02
0.008
0.118
0.0689
0.0374
0.118
0.024
10 deg.
8/9
TSM1051
PACKAGE MECHANICAL DATA
8 PINS - PLASTIC MICROPACKAGE (SO8)
Millimeters
Inches
Dim.
Min.
A
a1
a2
a3
b
b1
C
c1
D
E
e
e3
F
L
M
S
Typ.
Max.
0.65
0.35
0.19
0.25
1.75
0.25
1.65
0.85
0.48
0.25
0.5
4.8
5.8
5.0
6.2
0.1
Min.
Typ.
Max.
0.026
0.014
0.007
0.010
0.069
0.010
0.065
0.033
0.019
0.010
0.020
0.189
0.228
0.197
0.244
0.004
45° (typ.)
1.27
3.81
3.8
0.4
0.050
0.150
4.0
1.27
0.6
0.150
0.016
0.157
0.050
0.024
8° (max.)
Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the
consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from
its use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications
mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information
previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or
systems without express written approval of STMicroelectronics.
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© 2002 STMicroelectronics - Printed in Italy - All Rights Reserved
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