ETC TSM101AID

TSM101/A

VOLTAGE AND CURRENT CONTROLLER
.
.
.
..
1.24V SERIES VOLTAGE REFERENCE WITH
10mA OUTPUT CURRENT AND 1% PRECISION (TSM101A)
TWO OPERATIONAL AMPLIFIERS WITH
ORED OUTPUT AND 1MHZ GAIN BANDWIDTH PRODUCT
BUILT-IN CURRENT GENERATOR WITH ENABLE/DISABLE FUNCTION
4.5 TO 32V SUPPLY VOLTAGE RANGE
SO8, DIP8 AND TSSOP8 PACKAGES
N
DIP8
(Plastic Package)
D
SO8
(Plastic Micropackage)
P
TSSOP8
(Thin Shrink Small Outline Package)
ORDER CODES
DESCRIPTION
The TSM101/TSM101Aintegrated circuit incorporates a high stability series band gap voltage reference, two ORed operational amplifiers and a
current source.
This IC compares the DC voltage and the current
level at the output of a switching power supply to
an internal reference. It provides a feedback
through an optocoupler to the PWM controller IC in
the primary side.
The controlled current generator can be used to
modify the level of current limitation by offsetting
the information coming from the current sensing
resistor.
APPLICATIONS
This circuit is designed to be used in battery chargers with a constant voltage and a limited output
current.
It can be used in every types of applicationrequiring
a precision voltage regulation and current limitation.
Other applications include voltage supervisors,
over voltage protection...
June 1999
Part Number
TSM101C/AC
TSM101I/AI
Package
Temperature
Range
N
D
P
-20, +80oC
•
•
•
•
•
•
o
-40, +105 C
PIN CONNECTIONS
1
Vref
8
2
7
3
6
4
5
1/15
TSM101/A
ABSOLUTE MAXIMUM RATINGS
Symbol
Parameter
Value
Unit
VCC
DC Supply Voltage - (note 1)
36
V
Iout
Output Current - (note 2)
20
mA
Pd
Power Dissipation
200
mW
Vin
Input Voltage - (note 3)
Iin
Input Current
Tstg
Tj
Tthja
-0.3, VCC -1.5
V
±1
mA
Storage Temperature
Maximum Junction Temperature
Thermal Resistante Junction to Ambiant
-40 to +125
o
C
150
o
C
o
130 to 200
C/W
Notes : 1. All voltages values, except differential voltage are with respect to network ground terminal
2. The voltage reference is not protected against permanent short circuit
OPERATING CONDITIONS
Symbol
TSM101C/AC/I/AI
Parameter
VCC
Supply Voltage
Toper
Operating Free Air Temperature Range
Value
4.5 to 32
Unit
V
o
Tmin. to Tmax.
C
ELECTRICAL CHARACTERISTICS
Tamb = 25oC, VCC = 15V (unless otherwise specified)
OPERATIONAL AMPLIFIER : TSM101C/I/AC/AI
Symbol
Parameter
ICC
Total Supply Current
Vi
Input Voltage Range
Vio
Input Offset Voltage
Iib
Input Bias Current
@ Vin = 1.2V on pin 7 and Vin = 0V on pin 5
Isink
Avo
Output Sink Current, Vol = 2.5V
Large Signal Voltage Gain
Test Conditions
Min.
Typ.
VCC = 15V
0
Max.
Unit
2
mA
VCC -1.5V
V
25oC
Tmin. <T amb.<Tmax.
-5
-7
1
5
7
mV
o
-700
-1000
-300
0
0
25 C
Tmin. <T amb.<Tmax.
nA
o
15
25 C
Tmin. <T amb.<Tmax.
8
RL = 2kΩ
Tmin. <T amb.<Tmax.
15
Tmin. <T amb.<Tmax.
65
mA
V/mV
SVR
Supply Voltage Rejection Ratio
CMR
Common Mode Rejection Ratio
Tmin. <T amb.<Tmax.
80
dB
GBP
Gain Bandwidth Product
VCC = 15V, F = 100kHz
Vin = 10mV, RL = 2kΩ
CL = 100pF
1
MHz
Ioh
Output Leakage Current
25 C
Tmin. <T amb.<Tmax.
2/15
o
90
dB
2
7
µA
TSM101/A
ELECTRICAL CHARACTERISTICS
Tamb = 25oC, VCC = 15V (unless otherwise specified)
VOLTAGE REFERENCE : TSM101
Symbol
Parameter
Vref
Reference Voltage
Kvt
Temperature Stability
TSM101C
Test Conditions
Iout = 1mA, Tamb. = 25oC
TSM101I
Unit
Min.
Typ.
Max.
Min.
Typ.
Max.
1.21
1.24
1.27
1.21
1.24
1.27
V
30
100
35
120
ppm/ C
Tmin. <T amb.<Tmax.
o
Reglo
Load Regulation
1 < Iout < 10mA
5
15
5
15
mV
R egli
Line Regulation
5 < Vin < 32V
3.5
10
3.5
10
mV
VOLTAGE REFERENCE : TSM101A
Symbol
Parameter
Vref
Reference Voltage
Kvt
Temperature Stability
TSM101AC
Test Conditions
o
Iout = 1mA, Tamb. = 25 C
TSM101AI
Unit
Min.
Typ.
Max.
Min.
Typ.
Max.
1.227
1.24
1.252
1.227
1.24
1.252
V
30
100
35
120
ppm/ C
Tmin. <T amb.<Tmax.
o
Reglo
Load Regulation
1 < Iout < 10mA
5
15
5
15
mV
R egli
Line Regulation
5 < Vin < 32V
3.5
10
3.5
10
mV
CURRENT GENERATOR : TSM101, TSM101A
Symbol
Parameter
Test Conditions
TSM101C/AC
Min.
TSM101I/AI
Max.
Min.
Typ.
Max.
Unit
1.4
1.4
mA
Kcgt
Temperature Stability
Tmin. <T amb.<Tmax.
500
600
ppm/ oC
C glir
Line Regulation
4.5 < VCC < 32V
0.003
Vcsen
Voltage at the enable
pin to have
IO = 1.4mA
Tmin. <T amb.<Tmax.
Vcsdis
Voltage at the enable
pin to have
IO = 0mA
Tmin. <T amb.<Tmax.
Icsen
Input Current on the
C sen pin
Tmin. <T amb.<Tmax.
Icsleak
Leakage Current
Vcs = 2V
Tmin. <T amb.<Tmax.
Io
Current Source
Typ.
0.03
0.003
0.6
2
0.03
mA
0.6
V
2
V
30
0.5
2
30
0.5
2
µA
µA
3/15
TSM101/A
8
Vre f
Gnd
1
+Vcc
Vre f
4
7
Vrin
Cs e n
Crre f
Crin
6
2
OUTP UT
3
5
DESCRIPTION
4/15
Name
Pin
Type
Vref
1
OUTPUT
Function
Voltage Reference Output 1.24V, 10mA max. Do not short circuit
Vrin
7
INPUT
Voltage Regulation Loop Input
C rin
5
INPUT
Current Limitation Loop Input, connected to the sense resistor
Crref
3
INPUT
Current Limitation Reference Input
C sen
2
INPUT
Current source enable input. This current source can be used to
offset the voltage measurement on the sense resistor and therefore to
modify the charge current. The current source is enabled when the
input voltage on pin 2 is lower than 0.8V.
OUTPUT
6
OUTPUT
Output pin common to the voltage regulation and current limitation
loops. This output can drive the primary side (LED) of an optocoupler.
VCC
8
INPUT
Power Supply Input (4.5 to 32VDC)
GND
4
INPUT
Ground
TSM101/A
APPLICATION NOTE
A BATTERY CHARGER USING THE TSM101
by S. LAFFONT and R. LIOU
This technical note shows how to use the TSM101
integrated circuit with a switching mode power
supply (SMPS) to realize a battery charger.
An example of realization of a 12V Nickel-cadmium
battery charger is given.
1 - TSM101 PRESENTATION
The TSM101 integrated circuit incorporates a high
stability series band gap voltage reference, two
ORed operational amplifiers and a current source
(Figure 1)
Figure 1 : TSM101 Schematic Diagram
1
Vref
A great majority of low or medium end power
supplies is voltage regulated by using shunt programmable voltage references like the TL431
(Figure 2).
The galvanic insulation of the control information is
done by using an opto-coupler in linear mode with
a variable photo current depending on the difference between the actual output voltage and the
desired one.
A current limitation is used to protect the power
supply against short circuits, but lacks precision.
This limitation is generally realized by sensing the
current of the power transistor, in the primary side
of the SMPS.
The role of the TSM101 is to make a fine regulation
of the output current of the SMPS and a precise
voltage limitation.
The primary current limitation is conserved and
acts as a security for a fail-safe operation if a
short-circuit occurs at the output of the charger.
8
2
7
3
6
4
5
This IC compares the DC voltage and the current
level at the output of a switching power supply to
an internal reference.It provides a feedback
through an optocoupler to the PWM controller IC in
the primary side.
The controlled current generator can be used to
modify the level of current limitation by offsetting
the information coming from the current sensing
resistor.
2 - PRINCIPLE OF OPERATION
The current regulation loop and the voltage limitation loop use an internal 1.24V band-gap voltage
reference. This voltage reference has a good precision (better than 1.5%) and exhibits a very stable
temperature behavior.
The current limitation is performed by sensing the
voltage across the low ohmic value resistor R5 and
comparing it to a fixed value set by the bridge
composed by R2 and R3 (Figure 3).
When the voltage on R5 is higher than the voltage
on R3 the output of the current loop operational
amplifier decreases. The optocoupler current increases and tends to reduce the output voltage by
the way of the PWM controller.
The voltage regulation is done by comparing a part
of the output voltage (resistor bridge R6, R7 and
P1) to the voltage reference (1.24V).
If this part is higher than 1.24V, the output of the
voltage loop operational amplifier decreases.
5/15
TSM101/A
Figure 2 : SMPS Using a TL431 as Voltage Controller
The optocoupler current increases and tends to
reduce the output voltage by the way of the PWM
controller.
By enabling the TSM101 current source (pin 2) it is
possible to offset the current sensing by a voltage
equal to :
ence of this diode on the charge is negligible if the
voltage drop (0.7V) is taken into account during the
design of the charger.
The voltage at the output of the charger is :
R6+R7
xVr
R6
and regarding R6 and R7 :
• Vout =
• Voff # R4 * Io with Io = 1.4mA
This offset lowers the output charge current and
this function can be used to charge two types of
batteries having different capacities. The current
source is enabled by connecting pin 2 to ground
• R6 = (
3 - CALCULATION OF THE ELEMENTS
The charge current is regulated at 700mA (if the
charge control input is left open) or 200mA (if the
charge control input is put to ground ), allowing the
charge of two different types of batteries.
• R7 = 12kΩ
3.1 - Voltage limitation
The end-of- charge voltage is limited at 1.45V/cell,
this is the recommended voltage for an ambient
temperature at 25oC.
A diode is generally inserted at the output of the
charger to avoid the discharge of the battery if the
charger is not powered. This diode is sometimes
directly integrated in the battery pack. The influ6/15
Vref
) x R7
Vout − Vref
P1, which is a part of R6 and R7 is not considered
in this equation.
The following values are used on the application
board :
• R6 = 1kΩ
• P1 = 220Ω, adjust for Voutput = 15.2V with the
battery replaced by a 1kΩ resistor
• R10 = short circuit
• C3 = 100nF
3.2 - Current regulation
R5 is the sense resistor used for current measurement.
TSM101/A
The current regulation is effective when the voltage
drop across R5 is equal to the voltage on pin 5 of
the TSM101 (assuming that the internal current
source is disabled).
For medium currents (<1A), a voltage drop across
R5 of 200mV = Vr5 is a good value, R5 can be
realized with standard low cost 0.5W resistors in
parallel.
Vr5
, R5 = 0.285Ω (four 1.2Ω resistor in
Ich
parallel)
R2 and R3 can be chosen using the following
formula :
• R5 =
• R2 = R3 x
(Vref − Vr5)
Vr5
CHARGE CONTROL
If the pin 2 is left open, the charge current is nominal
at # 700mA.
If pin 2 is connected to ground, the internal current
source is enabled, the current measurement is
off-setted by a voltage equal to :
• Vr4 = Io x R4 with Io = 1.4mA
This can be used to lower the charging current or
eventually to stop the charge, if Vr4 > Vr5
In our example, the current offset is equal to 700 200mA = 500mA, representing a voltage offset
Vr4 = 140mV across R4.
The following values are used on the application
board :
• R5 = 4 *1.2Ω 0.5W in parallel
• R4 = 100Ω
• R2 = 1.2kΩ
• R3 = 220Ω
• R9 = short circuit
• R1 = 10kΩ
• C2 = 100nF
• C5 = 100nF
• C1 = output capacitor of the SMPS
• C4 = 10µF
4 - SCHEMATIC DIAGRAM
Figure 2 represents a schematic of the output
circuit of a ”classical” SMPS using a TL431 for
voltage regulation. This circuit is modified to use
the TSM101 and the final circuit is represented in
figure 3.
Figure 3 : SMPS Using the TSM101
7/15
TSM101/A
5 - IMPROVEMENT
5.2. Power supply for TSM101
5.1. High frequency compensation
In applications requiring low voltage battery charge
or when the charger is in current regulation mode,
the outputvoltage can be too low to supply correctly
the TSM101.
The same problem occurs when the output is shortcircuited.
A solution to provide a quasi constant supply voltage to the TSM101 is shown at figure 4 : an auxiliary
Two R-C devices (R9 + C2 & R10 + C3) are used
to stabilize the regulation at high frequencies.
The calculation of these values is not easy and is
a function of the transfer function of the SMPS.
A guess value for the capacitors C2 and C3 is
100nF.
Figure 4 : An Auxiliary Winding for TSM101 Power Supply
winding is added at the secondary side of the
transformer.
This winding is forward coupled to the primary
winding, the voltage across it is directly proportional
to the mains rectified voltage, even if the flyback
voltage is close to zero.
As this auxiliary winding is a voltage source, it is
necessary to add a resistor (R11) on the cathode
of the rectifier (D3) to limit the current.
8/15
A low cost regulator (Q2 and Zener diode D4) is
used to power the TSM101. This is necessary with
autoranging SMPS with wide input voltages, for
example 90 to 240V without switching. In standard
SMPS with voltage range from 200 to 240VAC or
100 to 130VAC, this regulator can be removed and
replaced by the small power supply shown on
figure 5 (Raux, Caux, D2).
TSM101/A
5.3. Higher Precision for the Voltage Control
The voltage drop through the sense resistor R5
offsets the voltage measurement. In most battery
charging applications, this offset is not taken into
account because the error is negligeable compared to the end-of-charge voltage due to the fact
that the charging current value decreases drastically during the final phase of the battery charging.
But in other applications needing highest possible
precision in voltage control, another connecting
schematic is possible for TSM101 as shown on
figure 5.
In this schematic, the 0V reference is defined as
the common point between the sense resistor, the
0V Output Voltage, the foot of the resistor bridge
R6/R7, and the ground (pin 4) of the TSM101.
TSM101A(1% internal voltage referenceprecision)
is required in such applications.
Figure 5 : Precise Output Voltage Control
5.4. An example of application where the
charging current is different according to the
charging phase.
The following application includes a specific recommendation which requires that the charging current
should be fixed to Ich1 = 800mAin normal charging
conditions, and Ich2 = 200mA when the cell voltage is below Vl=2.5V to optimize the cell life-time.
Moreover, an Charging Status LED should be
switched off when the cell voltage is above
Vh=6.5V.
Figure 6 shows how this can easily be achieved
using an additional dual comparator (type LM393)
where the first operator (C1) is used to activate the
TSM101 internal current generator to offset the
current measurement thanks to R4, and the second
(C2) is used to switch the status LED off. On figure
6, the status signal is determined by voltage measurement, this could as well be achieved by current
measurement.
If V5 = 100mV is the maximum tolerable voltage
drop through the sense resistor R5 during normal
9/15
TSM101/A
charging conditions, then the following calculations
apply :
Current Control :
R5 = V5 / Ich1 = 0.1 / 0.8 = 0.125
R5 = 125mΩ
V5 = Vref x R3 / (R2 + R3) with R2 + R3 ~ 12kΩ
and Vref = 1.24V
R3 = 1kΩ, R2 = 11.4kΩ
V5 = R4 x Io + R5 x Ich2, therefore, R4 = (V5 - R5
x Ich2) / Io with Io = 1.4mA
Figure 6 : Optimized Charging Conditions
10/15
R4 = 53.6Ω
Vref = Vl x R15 / (R14 + R15) with Vl = 2.5V and
R14 + R15 ~ 20kΩ
R15 = R14 = 10kΩ
Voltage Control :
Vref = Vh x R6 / (R6 + R7) with Vh = 6.5V and
R6 + R7 ~ 12kΩ
R6 = 2.36kΩ, R7 = 10kΩ
Vref = Vh R17 / (R16 + R17)
R17 = 10kΩ, R16 = 42kΩ
TSM101/A
EVALUATION BOARD - TECHNICAL NOTE
TSM101 integrates in the same 8 pin DIP or SO
package
• one 1.24V precision voltage reference
• two operationnal amplifiers
• two diodes which impose a NOR function on the
outputs of the operationnal amplifiers
• one current source which can be activated/ inhibited thanks to an external pin.
An immediate way to take advantage of the high
integration and reliability of TSM101 is to use it as
a voltage and current controller on power supplies
secondary. The application note AN896 describes
precisely how to use TSM101 in an SMPS battery
charger.
The TSM101 Evaluation Board is adaptable to any
power supply or battery charger (SMPS or linear)
as a voltage and current controller with minimal
constraints from the user.
HOW TO USE THE TSM101 EVALUATION
BOARD ?
The generic Electrical Schematic is shown on figure 1. It represents an incomplete SMPS power
supply where the primary side is simplified.
The ”IN+”and ”IN-” power inputs of the evaluation board should be connected directly to the
power lines of the power supply secondary.
The ”Vcc” input of the evaluation board should be
connected to the auxiliary supply line.
In the case of an SMPS power supply, the ”Reg”
output of the evaluation board should be connected to the Optocoupler input to regulate the
PWM block in the primary side. In the case of a
linear power supply, the ”Reg” output should be
connected to the base of the darlington to regulate
the power output.
A diode might be needed on the output of the
evaluation board in the case of a battery charger
application to avoid the discharge of the battery
when the charger is not connected.
COMPONENTS CALCULATIONS
The voltage control is given by the choice of the
resistor bridge R6/R7 (and the trimmer P1) due to
equation 1 :
• Vref = R6/(R6+R7)xVout
where Vref = 1.24V
eq1
Figure 1
11/15
TSM101/A
The current control is given by the choice of the
voltage drop through the sense resistor R5 (to be
linked to the nominal current of the application) and
by the value of the sense resistor itself.
For medium currents (< 1A), a good value for the
voltage drop through R5 can be Vsense = 200mV
(dissipation < 200mW).
The resistor bridge R2/R3 should be chosenfollowing equation 2 :
• Vsense = R3/(R2+R3)xVref
eq2
The total value of the resistor bridge should be in
the range of the kΩ in order to ensure a proper
charge for the voltage reference(in the range of the
mA).
To set the current limit, the sense resistor R5 should
be chosen following equation 3 :
• Ilim = Vsense/R5
eq3
The internal current generator (Isce) can be used
to offset the current limitation with a lower value.
This current generator is activated by connecting
pin 2 to ground. It is inhibited if pin 2 is connected
to the positive rail via the pull up resistor R1.
The current offset is given by the choice of the
resistor R4.
If Ilim1 is the current limit calculated in the previous
paragraph, and Ilim2 is the current limit that is to be
set when pin 2 is connected to ground, R4 should
be chosen following equation 4 :
• R4 = (Vsense - Ilim2xR5)/Isce
eq4
where Isce = 1.4mA
C4 and C5 are bypass capacitors used to
smoothen the regulated outputs.
C2 and C3 are capacitors used for high frequency
compensation.
EXAMPLES OF COMPONENT LISTS
Table 1 summerizes a few examples of component
lists to generate quickly 15V/700mA/20 0mA,
12V/1A/500mAor 8.2V/200mA/100mAvoltage and
current regulations.
12/15
Table 1
Voltage /
Current
Control
15V
700mA
200mA
12V
1A
500mA
8.2V
200mA
100mA
R1
10kΩ
10kΩ
10kΩ
R2
1.2kΩ
1.2kΩ
1.2kΩ
R3
220Ω
220Ω
220Ω
R4
100Ω
68Ω
68Ω
1Ωx1
R5
1.2Ωx4
0.8Ωx4
R6
1kΩ
1kΩ
1kΩ
R7
12kΩ
8.2kΩ
5.6kΩ
P1
100Ω
100Ω
100Ω
0Ω
0Ω
0Ω
C2
100nF
100nF
100nF
C3
100nF
100nF
100nF
C4
10µF
22µF
4.7µF
C5
100nF
100nF
100nF
2 straps
Figure 2 represents in real dimensions thePCB and
the silkscreen of the TSM101 Evaluation board.
Figure 2
TSM101/A
PACKAGE MECHANICAL DATA
8 PINS - PLASTIC DIP
Dim.
A
a1
B
b
b1
D
E
e
e3
e4
F
i
L
Z
Min.
Millimeters
Typ.
3.32
0.51
1.15
0.356
0.204
Max.
1.65
0.55
0.304
10.92
9.75
7.95
Min.
0.020
0.045
0.014
0.008
Max.
0.065
0.022
0.012
0.430
0.384
0.313
2.54
7.62
7.62
3.18
Inches
Typ.
0.131
0.100
0.300
0.300
6.6
5.08
3.81
1.52
0.125
0260
0.200
0.150
0.060
13/15
TSM101/A
PACKAGE MECHANICAL DATA
8 PINS - PLASTIC MICROPACKAGE (SO)
Dim.
A
a1
a2
a3
b
b1
C
c1
D
E
e
e3
F
L
M
S
14/15
Min.
Millimeters
Typ.
0.1
0.65
0.35
0.19
0.25
Max.
1.75
0.25
1.65
0.85
0.48
0.25
0.5
Min.
Inches
Typ.
0.026
0.014
0.007
0.010
Max.
0.069
0.010
0.065
0.033
0.019
0.010
0.020
0.189
0.228
0.197
0.244
0.004
o
45 (typ.)
4.8
5.8
5.0
6.2
1.27
3.81
3.8
0.4
0.050
0.150
4.0
1.27
0.6
0.150
0.016
o
8 (max.)
0.157
0.050
0.024
TSM101/A
PACKAGE MECHANICAL DATA
8 PINS -THIN SHRINK SMALL OUTLINE PACKAGE
Dim.
Millimeters
Min.
Typ.
A
Min.
Typ.
1.20
A1
0.05
A2
0.80
b
c
D
2.90
Max.
0.05
0.15
0.01
1.05
0.031
0.19
0.30
0.007
0.15
0.09
0.20
0.003
0.012
3.10
0.114
4.50
0.169
8o
0o
0.75
0.09
E
E1
Inches
Max.
1.00
3.00
6.40
4.30
e
4.40
0o
l
0.50
0.60
0.039
0.118
0.041
0.122
0.252
0.65
k
0.006
0.173
0.177
0.025
8o
0.0236
0.030
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