1
TSM1012
LOW CONSUMPTION VOLTAGE AND CURRE NT
CONTROLLER FOR BATTERY CHARGERS AND ADAPTORS
■ CONSTANT VOLTAGE AND CONSTANT
CURRENT CONTROL
■ LOW CONSUMPTION
■ LOW VOLTAGE OPERATION
■ LOW EXTERNAL COMPONENT COUNT
■ CURRENT SINK OUTPUT STAGE
■ EASY COMPENSATION
■ HIGH AC MAINS VOLTAGE REJECTION
VOLTAGE REFERENCE
■ FIXED OUTPUT VOLTAGE REFERENCE
1.25V
■ 0.5% AND 1% VOLTAGE PRECISION
DESCRIPTION
TSM1012 is a highly integrated solution for SMPS
applications requiring CV (constant voltage) and
CC (constant current) mode.
TSM1012 integrates one voltage reference and
two operational amplifiers (with ORed outputs common collect or s).
The voltage reference combined with one
operational amplifier makes it an ideal voltage
controller. The other operational, combined with
few external resistors and the voltage reference,
can be used as a current limiter.
APPLICATIONS
■ ADAPTERS
■ BATTERY CHARGERS
ORDER CODE
Part
Number
TSM1012I -40 to 105°C • 1 M1012
TSM1012AI -40 to 105°C • 0.5 M1012A
TSM1012I -40 to 105°C • 1M804
TSM1012AI -40 to 105°C • 0.5 M805
D = Small Outline Package (SO) - also available in Tape & Reel (DT
S = Small Outline Package (MiniSO8) - also availabl e in Tape & Reel (ST)
Temperature
Range
Package Vref
Marking
SD%
D
SO-8
(Plastic Package)
(Plastic Micropackage)
S
MiniSO-8
PIN CONNECTIONS (top view)
Vref Vcc
1
28V
,25V
CC-
2
CC+ Gnd
3
CV- CV+
45
CC
CV
Out
8
7
6
February 2004
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TSM1012
PIN DESCRIPTION
SO8 & MiniSO8 Pin out
Name Pin # Type Function
Vref 1 Analog Output Voltage Reference
CC- 2 Analog Input Input pin of the operational amplifier
CC+ 3 Analog Input Input pin of the operational amplifier
CV- 4 Analog Input Input pin of the operational amplifier
CV+ 5 Analog Input Input pin of the operational amplifier
Gnd 6 Power Supply Ground Line. 0V Reference For All Voltages
Out 7 Analo g Ou tpu t Output of the two opera tio na l amp lifie r
Vcc 8 Power Supply Power supply line.
ABSOLUTE MAXIMUM RATINGS
Symbol DC Supply Voltage Value Unit
Vcc DC Supply Voltage (50mA =< Icc) -0.3V to Vz V
Vi Input Voltage -0.3 to Vcc V
Tstg Storage temperature -55 to 150 °C
Tj Junction temperature 150 °C
Iref Voltage reference output current 2.5 mA
ESD Electrostatic Discharge 2 kV
Rthja Thermal Resistance Junction to Ambient Mini SO8 package 180 °C/W
Rthja Thermal Resistance Junction to Ambient SO8 package 175 °C/W
OPERATING CONDITIONS
Symbol Parameter Value Unit
Vcc DC Supply Conditions 4.5 to Vz V
Toper Operational temperature -40 to 105 °C
2/8
TSM1012
ELECTRICAL CHARACTERISTICS
Tamb = 25°C and Vcc = +18V (unless otherwise specified)
Symbol Parameter Test Condition Min Typ Max Unit
Total Current Consumpt ion
Icc Total Supply Current, excluding current
in Voltage Reference
1)
.
Vcc = 18V, no load
Tmin. < Tamb < Tmax.
Vz Vcc clamp voltage Icc = 50mA 28 V
Operators
Input Offset Voltage
V
io
TSM1012
TSM1012A
DV
Input Offset Voltage Drift 7 µV/°C
io
Input Offset Current T
I
io
I
Input Bias Current T
ib
SVR Supply Voltage Rejection Ration V
= 25°C
T
amb
≤ T
T
min.
T
amb
T
min.
amb
T
min.
amb
T
min.
CC
≤ T
amb
max.
= 25°C
≤ T
≤ T
amb
max.
= 25°C
≤ T
≤ T
amb
max.
= 25°C
≤ T
≤ T
amb
max.
= 4.5V to 28V 65 100 dB
Vicm Input Common Mode Voltage Range 0 Vcc-1.5 V
CMR Common Mode Rejection Ratio T
T
amb
min.
= 25°C
≤ T
amb
≤ T
max.
70
60
Output stage
Gm Transconduction Gain. Sink Current
Only
2)
Vol Low outp ut vo ltage at 5 mA sin kin g
current
Ios Output Short Circuit Current. Output to
(Vcc-0.6V). Sink Current Only
T
T
T
T
T
amb
min.
min.
amb
min.
= 25°C
≤ T
amb
≤ T
amb
= 25°C
≤ T
amb
≤ T
≤ T
≤ T
max.
max.
max.
0.5
6
5
Voltage reference
V
Reference Input Voltage
∆V
ref
TSM1012 1% precision
TSM1012A 0.5% precision
Reference Input Voltage Deviation Over
ref
T
T
T
T
T
amb
min.
amb
min.
min.
= 25°C
≤ T
amb
= 25°C
≤ T
amb
≤ T
amb
≤ T
≤ T
≤ T
max.
max.
max.
1.238
1.225
1.244
1.237
Temperature Range
RegLine Reference input voltage deviation over
Iload = 1mA 20 mV
Vcc range.
RegLoad Reference input voltage deviation over
output current.
1. Test conditions: pin 2 and 6 connected to GND, pin 4 and 5 connected to 1. 25V, pin 3 connected to 200mV.
2. The current depends on the difference voltage between the negative and the positive inputs of the amplifier. If the voltage on the minus
input is 1mV higher than the positive amplifier, the sinking current at the outpu t OUT will be incr eased by Gm*1mA.
Vcc = 18V,
0 < Iload < 2.5mA
100 180 µA
1
4
mV
5
0.5
2
3
23050nA
20
50
150
200
nA
85 dB
1
mA/mV
1
250 400 mV
10 mA
1.25
1.262
1.273
1.25
1.256
1.261
20 30 mV
10 mV
V
3/8
TSM1012
2
V
G
O
O
Figure 1 : Internal Schematic
8
cc
1
Vref
1,25V
8V
CV+
CV
ut
5
CC+
CC
3
CC-
nd
CV-
2 6
Figure 2 : Typical Adapter or Battery Charger Application Using TSM1012
Rlimit
D2
CV
CC
Vcc
8
28V
ut
7
4
CV-
PWM
controller
TSM1012
C4
47nF
C1
C2
1
5
R4
3
Vref
1,25V
CV+
CC+
7
4
optocoupler
secondary side
OUT+
R3
Rvc1
22K
Cvc1
2,2nF
R2
C3
optocoupler
primary side
CC-
R5
D1
Rsense
Gnd
2 6
Ric2
1K
Ric1
22K
Cic1
2,2nF
R1
OUT-
In the above applicati on s chem ati c, t he T SM1012 is used on the se con dar y si de 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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TSM1012
PRINCIPLE OF OPERATION AND APPLICATION HINTS
1. Voltage and Current Control
1.1. Voltage Control
The voltage loop is co ntrolled via a first trans conductance operational amplifi er, the res istor bridg e
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 b e highly resist ive. 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 ins erted
between the load and the voltage regulation resistor bridge to avo id 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).
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
Therefore, for most adapter and battery charger
applications, a quarter-watt, or half-watt resistor to
make the current sensing function is sufficient.
The current sinking outputs of the two trans-connuctance operational amplifiers are common (to
the output of the IC). This m akes an ORi ng function which ensures that whenever the current or
the voltage reaches too hig h value s, the opt ocoupler is activated.
The relation between the controlled current and
the controlled output voltage can be described
with a square charac teristic as shown in the following V/I output-power graph.
Figure 3 : Output voltage versus output current
Vout
Voltage regulation
1.2. Current Control
The current loop is controlled via the second
trans-conductance operational amplifier, the
sense resistor Rsense, and the optocoupler.
Vsense threshold is achieved externally by a resistor bridge tied to the Vre f voltage ref erence. Its
middle point is tied to the positive inp ut of the current control ope ra tio nal a mpl ifi er, and i ts fo ot is t o
be connected to lower potential point of the sense
resistor as shown o n the follow ing figure. T he resistors of this bridge are ma tched to provide the
best precision possible
The control equation verifies:
Rsense x Ilim = Vsense eq2
Vsense = R5*Vref/(R4+R5)
Ilim = R5*Vref/(R4+R5)*Rsense eq2'
where Ilim is the desired limited current, and
Vsense is the threshold voltage for the current
control loop.
TSM1012 Vcc : independent power supply
Secondary current regulation
0
TSM1012 Vcc : On power output
Primary current regulation
2. Compensation
The voltage-contr ol trans-condu ctance oper ational amplifier can be ful ly compensated. Bot h of its
output and negative i nput 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=22KΩ in series.
Current regulation
Iout
5/8
TSM1012
O
The current-contr ol trans-conductance oper ational amplifier can be fully compensated. Bot h of its
output and negative i nput 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.
3. Start Up and Short Circuit Conditions
Under start-up or short-circuit conditions the
TSM1012 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, w hich 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 TSM1012 has to be ensured
under any condition. It would then be necessary to
add some circuitry to su pply the chi p with a separate power line. This can be achieved in numerous
ways, including an additional winding on the transformer.
4. Voltage clamp
The following sche matic shows how to realize a
low-cost power suppl y for the TSM1012 (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 TSM1012
supply voltage is 28V. In the aim to protect he
TSM1012 against su ch how voltage values a internal zener clamp is integrated.
Rlimit = (Vcc-Vz)Ivz
Figure 4 : Clamp voltage
cc
Rlimit
Vcc
Ivz
TSM1012
Vz
28V
Figure 5 :
PWM
controller
optocoupler
primary side
Rlimit
optocoupler
Cvc1
2,2nF
secondary side
OUT+
R2
C3
R1
OUT-
D2
Gnd
CV
CC
Vcc
28V
8
CV-
Ric1
22K
R3
Rvc1
ut
22K
7
4
Cic1
2,2nF
TSM1012
R4
R5
1
CV+
5
CC+
3
Rsense
Vref
1,25V
CC-
2 6
Ric2
1K
C4
47nF
C1
C2
D1
6/8
TSM1012
PACKAGE MECHANICAL DATA
SO-8 MECHANICAL DATA
DIM.
A 1.35 1.75 0.053 0.069
A1 0.10 0.25 0.04 0.010
A2 1.10 1.65 0.043 0.065
B 0.33 0.51 0.013 0.020
C 0.19 0.25 0.007 0.010
D 4.80 5.00 0.189 0.197
E 3.80 4.00 0.150 0.157
e 1.27 0.050
H 5.80 6.20 0.228 0.244
h 0.25 0.50 0.010 0.020
L 0.40 1.27 0.016 0.050
k ˚ (max.)
ddd 0.1 0.04
MIN. TYP MAX. MIN. TYP. MAX.
mm. inch
8
0016023/C
7/8
TSM1012
PACKAGE MECHANICAL DATA
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 pa tent rights of STMicroelectronics . Specifications
mentioned in this publication are sub ject to change without notice. This publication supersedes and replaces all information
previously supplied. STMicroelectronics products are not authorized for use a s critical components in life support devices or
systems without express written approval of STMicroelectronics.
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