TSM1012
LOW CONSUMPTION VOLTAGE AND CURRENT
CONTROLLER FOR BATTERY CHARGERS AND ADAPTORS
s
CONSTANT VOLTAGE AND CONSTANT
s
s
s
s
s
s
CURRENT CONTROL
LOW CONSUMPTION
LOW VOLTAGE OPERATION
LOW EXTERNAL COMPONENT COUNT
CURRENT SINK OUTPUT STAGE
EASY COMPENSATION
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
D
SO-8
(Plastic Package)
S
MiniSO-8
(Plastic Micropackage)
PIN CONNECTIONS
(top view)
1
Vref
1,25V
28V
Vcc
8
2
CC-
CC
CC+
CV
Out
7
s
ADAPTERS
s
BATTERY CHARGERS
ORDER CODE
Part
Number
TSM1012I
TSM1012AI
TSM1012I
TSM1012AI
Temperature Package Vref
Range
S
D
%
-40 to 105°C
-40 to 105°C
-40 to 105°C
-40 to 105°C
•
•
•
•
1
0.5
1
0.5
Marking
4
3
Gnd
6
CV-
CV+
5
M1012
M1012A
M804
M805
D =
Small Outline Package (SO) - also available in Tape & Reel (DT
S =
Small Outline Package (MiniSO8) - also available in Tape & Reel (ST)
February 2004
1/8
TSM1012
ELECTRICAL CHARACTERISTICS
Tamb = 25°C 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)
.
Vcc clamp voltage
Vcc = 18V, no load
Tmin. < Tamb < Tmax.
Icc = 50mA
100
28
180
µA
V
Vz
Operators
Input Offset Voltage
V
io
TSM1012
TSM1012A
DV
io
I
io
I
ib
SVR
Vicm
CMR
T
amb
= 25°C
T
min.
≤
T
amb
≤
T
max.
T
amb
= 25°C
T
min.
≤
T
amb
≤
T
max.
T
amb
= 25°C
T
min.
≤
T
amb
≤
T
max.
T
amb
= 25°C
T
min.
≤
T
amb
≤
T
max.
V
CC
= 4.5V to 28V
T
amb
= 25°C
T
min.
≤
T
amb
≤
T
max.
65
0
70
60
1
0.5
7
2
20
50
100
4
5
2
3
mV
Input Offset Voltage Drift
Input Offset Current
Input Bias Current
Supply Voltage Rejection Ration
Input Common Mode Voltage Range
Common Mode Rejection Ratio
µV/°C
30
50
150
200
Vcc-1.5
nA
nA
dB
V
dB
85
Output stage
Gm
Vol
Ios
Transconduction Gain. Sink Current
Only
2)
Low output voltage at 5 mA sinking
current
Output Short Circuit Current. Output to
(Vcc-0.6V). Sink Current Only
T
amb
= 25°C
T
min.
≤
T
amb
≤
T
max.
T
min.
≤
T
amb
≤
T
max.
T
amb
= 25°C
T
min.
≤
T
amb
≤
T
max.
6
5
0.5
1
1
250
10
400
mA/mV
mV
mA
Voltage reference
V
ref
Reference Input Voltage
TSM1012 1% precision
TSM1012A 0.5% precision
∆V
ref
T
amb
= 25°C
T
min.
≤
T
amb
≤
T
max.
T
amb
= 25°C
T
min.
≤
T
amb
≤
T
max.
1.238
1.225
1.244
1.237
1.25
1.25
20
1.262
1.273
1.256
1.261
30
20
10
V
Reference Input Voltage Deviation Over T
min.
≤
T
amb
≤
T
max.
Temperature Range
Iload = 1mA
Vcc = 18V,
0 < Iload < 2.5mA
mV
mV
mV
RegLine Reference input voltage deviation over
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 output OUT will be increased by Gm*1mA.
3/8
TSM1012
PRINCIPLE OF OPERATION AND APPLICATION HINTS
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 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 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
Vout
Voltage regulation
Current regulation
0
TSM1012 Vcc : independent power supply
Secondary current regulation
TSM1012 Vcc : On power output
Primary current regulation
Iout
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=22KΩ in series.
5/8
Embedded System
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