1/8
s
CONSTANT VOLTAGE AND CONSTANT
CURRENT CONTROL
s
LOW CONSUMPTION
s
LOW VOLTAGE OPERATION
s
LOW EXTERNAL COMPONENT COUNT
s
CURRENT SINK OUTPUT STAGE
s
EASY COMPENSATION
s
HIGH AC MAINS VOLTAGE REJECTION
VOLTAGE REFERENCE
s
FIXED OUTPUT VOLTAGE REFERENCE
1.25V
s
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 collectors).
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
s
ADAPTERS
s
BATTERY CHARGERS
ORDER CODE
D = Small Outline Package (SO) - also available in Tape & Reel (DT
S = Small Outline Package (MiniSO8) - also available in Tape & Reel (ST)
PIN CONNECTIONS (top view)
Part
Number
Temperature
Range
Package Vref
Marking
S
D
%
TSM1012I
-40 to 105C
1
M1012
TSM1012AI
-40 to 105C
0.5
M1012A
TSM1012I
-40 to 105C
1
M804
TSM1012AI
-40 to 105C
0.5
M805
D
SO-8
(Plastic Package)
S
MiniSO-8
(Plastic Micropackage)
1
28V
Vref
Vcc
CC
CC-
CC+
Gnd
CV
CV-
CV+
Out
1,25V
2
3
4
5
6
7
8
February 2004
TSM1012
LOW CONSUMPTION VOLTAGE AND CURRENT
CONTROLLER FOR BATTERY CHARGERS AND ADAPTORS
TSM1012
2/8
PIN DESCRIPTION
SO8 & MiniSO8 Pin out
ABSOLUTE MAXIMUM RATINGS
OPERATING CONDITIONS
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
Analog Output
Output of the two operational amplifier
Vcc
8
Power Supply
Power supply line.
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
Symbol
Parameter
Value
Unit
Vcc
DC Supply Conditions
4.5 to Vz
V
Toper
Operational temperature
-40 to 105
C
TSM1012
3/8
ELECTRICAL CHARACTERISTICS
Tamb = 25C and Vcc = +18V (unless otherwise specified)
Symbol
Parameter
Test Condition
Min
Typ
Max
Unit
Total Current Consumption
Icc
Total Supply Current, excluding current
in Voltage Reference
1)
.
1. Test conditions: pin 2 and 6 connected to GND, pin 4 and 5 connected to 1.25V, pin 3 connected to 200mV.
Vcc = 18V, no load
Tmin. < Tamb < Tmax.
100
180
A
Vz
Vcc clamp voltage
Icc = 50mA
28
V
Operators
V
io
Input Offset Voltage
TSM1012
TSM1012A
T
amb
= 25C
T
min.
T
amb
T
max.
T
amb
= 25C
T
min.
T
amb
T
max.
1
0.5
4
5
2
3
mV
DV
io
Input Offset Voltage Drift
7
V/C
I
io
Input Offset Current
T
amb
= 25C
T
min.
T
amb
T
max.
2
30
50
nA
I
ib
Input Bias Current
T
amb
= 25C
T
min.
T
amb
T
max.
20
50
150
200
nA
SVR
Supply Voltage Rejection Ration
V
CC
= 4.5V to 28V
65
100
dB
Vicm
Input Common Mode Voltage Range
0
Vcc-1.5
V
CMR
Common Mode Rejection Ratio
T
amb
= 25C
T
min.
T
amb
T
max.
70
60
85
dB
Output stage
Gm
Transconduction Gain. Sink Current
Only
2)
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 output OUT will be increased by Gm*1mA.
T
amb
= 25C
T
min.
T
amb
T
max.
0.5
1
1
mA/mV
Vol
Low output voltage at 5 mA sinking
current
T
min.
T
amb
T
max.
250
400
mV
Ios
Output Short Circuit Current. Output to
(Vcc-0.6V). Sink Current Only
T
amb
= 25C
T
min.
T
amb
T
max.
6
5
10
mA
Voltage reference
V
ref
Reference Input Voltage
TSM1012 1% precision
TSM1012A 0.5% precision
T
amb
= 25C
T
min.
T
amb
T
max.
T
amb
= 25C
T
min.
T
amb
T
max.
1.238
1.225
1.244
1.237
1.25
1.25
1.262
1.273
1.256
1.261
V
V
ref
Reference Input Voltage Deviation Over
Temperature Range
T
min.
T
amb
T
max.
20
30
mV
RegLine Reference input voltage deviation over
Vcc range.
Iload = 1mA
20
mV
RegLoad Reference input voltage deviation over
output current.
Vcc = 18V,
0 < Iload < 2.5mA
10
mV
TSM1012
4/8
In the above application schematic, the TSM1012 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.
Figure 1 : Internal Schematic
Figure 2 : Typical Adapter or Battery Charger Application Using TSM1012
28V
Vref
Vcc
CC
CC-
CC+
Gnd
CV
CV-
CV+
Out
1,25V
3
4
8
5
1
7
2
6
Rsense
C2
R2
R1
C1
C3
optocoupler
secondary side
Cic1
2,2nF
Cvc1
2,2nF
Ric1
22K
Rvc1
22K
Rlimit
R4
R5
R3
D1
D2
OUT+
OUT-
Ric2
1K
PWM
controller
optocoupler
primary side
TSM1012
28V
Vref
Vcc
CC
CC-
CC+
Gnd
CV
CV-
CV+
Out
1,25V
3
4
8
5
1
7
2
6
C4
47nF
5/8
1. Voltage and Current Control
1.1. Voltage Control
The voltage loop is controlled via a first transcon-
ductance operational amplifier, the resistor bridge
R1, R2, and the optocoupler which is directly con-
nected 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 100K
(or
more) would be appropriate for the resistors R1
and R2.
As an example, with R2 = 100K
, Vout = 4.10V,
Vref = 1.210V, then R1 = 41.9K
.
Note that if the low drop diode should be inserted
between the load and the voltage regulation resis-
tor bridge to avoid current flowing from the load
through the resistor bridge, this drop should be
taken into account in the above calculations by re-
placing Vout by (Vout + Vdrop).
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 re-
sistor bridge tied to the Vref voltage reference. Its
middle point is tied to the positive input of the cur-
rent 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 re-
sistors of this bridge are matched 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.
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-con-
nuctance operational amplifiers are common (to
the output of the IC). This makes an ORing func-
tion which ensures that whenever the current or
the voltage reaches too high values, the optocou-
pler is activated.
The relation between the controlled current and
the controlled output voltage can be described
with a square characteristic as shown in the fol-
lowing V/I output-power graph.
Figure 3 : Output voltage versus output current
2. Compensation
The voltage-control trans-conductance operation-
al 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=22K
in series.
Vout
Iout
Voltage regulation
C
u
r
r
ent
r
egulat
ion
TSM1012 Vcc : independent power supply
0
Secondary current regulation
TSM1012 Vcc : On power output
Primary current regulation
TSM1012
PRINCIPLE OF OPERATION AND APPLICATION HINTS
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