SGS Thomson Microelectronics TSM101C Datasheet

VOLTAGE AND CURRENTCONTROLLER
.
.
.
BUILT-IN CURRENT GENERATOR WITH EN­ABLE/DISABLEFUNCTION
.
4.5 TO 32V SUPPLYVOLTAGERANGE
.
SO8, DIP8 AND TSSOP8PACKAGES
TSM101/A
N
DIP8
(Plastic Package)
(Thin ShrinkSmall Outline Package)
(Plastic Micropackage)
P
TSSOP8
D
SO8
DESCRIPTION
The TSM101/TSM101Aintegratedcircuit incorpo­rates a highstabilityseries bandgapvoltagerefer­ence, 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 throughan optocouplerto the PWMcontroller IC in the primaryside.
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 circuitisdesignedtobe used in battery charg­ers with a constant voltage and a limited output current.
Itcanbeusedineverytypesofapplicationrequiring a precision voltage regulation and current limita­tion.
Other applications include voltage supervisors, over voltageprotection...
ORDERCODES
Part Number
TSM101C/AC -20, +80 TSM101I/AI -40,+105
PIN CONNECTIONS
Temperature
Range
1
2
3
4
Package
o
Vref
NDP
C •••
o
C •••
8
7
6
5
June 1999
1/15
TSM101/A
ABSOLUTEMAXIMUM RATINGS
Symbol Parameter Value Unit
V
CC
I
out
P
V
I
in
T
stg
T
T
thja
Notes : 1. All voltages values, except differential voltage are with respectto network ground terminal
OPERATING CONDITIONS
Symbol Parameter
V
CC
T
oper
DC Supply Voltage - (note 1) 36 V Output Current - (note 2) 20 mA Power Dissipation 200 mW
d
Input Voltage - (note 3) -0.3, VCC-1.5 V
in
Input Current ±1mA Storage Temperature -40 to +125 Maximum Junction Temperature 150
j
Thermal Resistante Junction to Ambiant 130 to 200
2. The voltagereference isnot protected against permanent short circuit
TSM101C/AC/I/AI
Value
Supply Voltage 4.5 to 32 V Operating FreeAir TemperatureRange T
min.
to T
max.
o o
o
C/W
Unit
o
C C
C
ELECTRICAL CHARACTERISTICS
=25oC, VCC=15V (unless otherwisespecified)
T
amb
OPERATIONALAMPLIFIER : TSM101C/I/AC/AI
Symbol Parameter Test Conditions Min. Typ. Max. Unit
Total Supply Current VCC= 15V 2 mA
I
CC
Input Voltage Range 0 VCC-1.5V V
V
i
Input Offset Voltage 25oC
V
io
I
Input Bias Current
ib
Output Sink Current, Vol= 2.5V 25oC
I
sink
A
Large Signal Voltage Gain RL=2k
vo
= 1.2V on pin 7 and Vin= 0V on pin 5 25oC
@V
in
SVR Supply VoltageRejection Ratio T
CMR Common Mode Rejection Ratio T
GBP Gain Bandwidth Product V
Output Leakage Current 25oC
I
oh
CC
V
in
T
min.<Tamb.<Tmax.
T
min.<Tamb.<Tmax.
T
min.<Tamb.<Tmax.
T
min.<Tamb.<Tmax. min.<Tamb.<Tmax. min.<Tamb.<Tmax.
= 15V, F = 100kHz
= 10mV, RL = 2k
= 100pF
C
L
T
min.<Tamb.<Tmax.
-5
-7
-700
-1000
15
7
-300 0 0
15 mA
8
15 65 90 dB
80 dB
1 MHz
2 7
V/mV
mV
nA
µA
2/15
ELECTRICAL CHARACTERISTICS
=25oC, VCC=15V (unlessotherwisespecified)
T
amb
VOLTAGEREFERENCE : TSM101
TSM101/A
Symbol Parameter Test Conditions
Reference Voltage I
V
ref
Temperature Stability T
K
vt
R R
Load Regulation 1 < I
eglo
Line Regulation 5 < Vin< 32V 3.5 10 3.5 10 mV
egli
= 1mA, T
out
min.<Tamb.<Tmax.
out
=25oC 1.21 1.24 1.27 1.21 1.24 1.27 V
amb.
< 10mA 5 15 5 15 mV
VOLTAGE REFERENCE : TSM101A
Symbol
V
ref
K
vt
R
eglo
R
egli
Parameter
Reference Voltage I Temperature Stability T Load Regulation 1 < I
Test Conditions
= 1mA, T
out
min.<Tamb.<Tmax.
amb.
< 10mA 5 15 5 15 mV
out
=25oC 1.227 1.24 1.252 1.227 1.24 1.252 V
Line Regulation 5 < Vin< 32V 3.5 10 3.5 10 mV
CURRENT GENERATOR : TSM101,TSM101A
Symbol Parameter Test Conditions
Current Source 1.4 1.4 mA
I
o
Temperature Stability T
K
cgt
Line Regulation 4.5 < VCC< 32V 0.003 0.03 0.003 0.03 mA
C
glir
V
V
I
I
csleak
Voltage at the enable
csen
pin to have
= 1.4mA
I
O
Voltage at the enable
csdis
pin to have
= 0mA
I
O
Input Current on the
csen
pin
C
sen
Leakage Current Vcs=2V
min.<Tamb.<Tmax.
T
min.<Tamb.<Tmax.
T
min.<Tamb.<Tmax.
T
min.<Tamb.<Tmax.
T
min.<Tamb.<Tmax.
TSM101C TSM101I
Min. Typ. Max. Min. Typ. Max.
Unit
30 100 35 120 ppm/oC
TSM101AC TSM101AI
Min. Typ. Max. Min. Typ. Max.
Unit
30 100 35 120 ppm/oC
TSM101C/AC TSM101I/AI
Min. Typ. Max. Min. Typ. Max.
Unit
500 600 ppm/oC
0.6 0.6 V
22V
30 30 µA
µA
0.5 2 0.5 2
3/15
TSM101/A
8
Vref Gnd
1
4 7
Vref
Vrin Cse n Crref
Crin
2
3 5
DESCRIPTION
Name Pin Type Function
V
ref
V
rin
C
rin
C
rref
C
sen
OUTPUT 6 OUTPUT Output pin common to the voltage regulation and current limitation
V
CC
GND 4 INPUT Ground
1 OUTPUT Voltage Reference Output 1.24V, 10mA max. Do notshort circuit 7 INPUT Voltage Regulation Loop Input 5 INPUT Current Limitation Loop Input, connected to the sense resistor 3 INPUT Current Limitation Reference Input 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.
loops. This output can drivethe primary side (LED) of an optocoupler.
8 INPUT Power Supply Input (4.5 to 32VDC)
+Vcc
6
OUTPUT
4/15
TSM101/A
APPLICATION NOTE
A BATTERY CHARGER USING THE TSM101
by S. LAFFONT and R. LIOU
This technical note showshow to use theTSM101 integrated circuit with a switching mode power supply(SMPS) to realize a battery charger.
An exampleof realizationofa12VNickel-cadmium battery chargeris given.
1 - TSM101PRESENTATION
The TSM101integratedcircuit incorporatesahigh stability series band gap voltage reference, two ORed operational amplifiers and a current source (Figure 1)
Figure 1 : TSM101Schematic Diagram
1
Vref
2
3
4
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 throughan optocouplerto the PWMcontroller IC in the primaryside.
The controlled current generator can be used to modify the level of current limitation by offsetting the information coming from the current sensing resistor.
8
7
6
5
A great majority of low or medium end power supplies is voltage regulated by using shunt pro­grammablevoltage referenceslike the TL431 (Figure 2).
Thegalvanic insulation of the controlinformationis doneby using an opto-couplerin linearmode with a variable photo current depending on the differ­ence between the actual output voltage and the desiredone.
A current limitation is used to protect the power supply against short circuits, but lacks precision. This limitation is generally realized by sensing the currentof the power transistor,in the primaryside of the SMPS.
Therole of theTSM101isto makea fineregulation of the output current of the SMPS and a precise voltagelimitation.
The primary current limitation is conserved and acts as a security for a fail-safe operation if a short-circuit occursat the output of the charger.
2 - PRINCIPLE OF OPERATION
Thecurrent regulation loop and the voltagelimita­tion loop use an internal 1.24V band-gap voltage reference.This voltage referencehas a good pre­cision(better than1.5%) and exhibitsa verystable temperaturebehavior.
The current limitation is performed by sensing the voltageacross thelowohmicvalueresistor R5and comparing it to a fixed value set by the bridge composedby R2and R3 (Figure 3).
Whenthe voltageon R5 is higher than the voltage on R3 the output of the current loop operational amplifier decreases. The optocoupler current in­creasesand tends to reducethe output voltage by the way of the PWM controller.
Thevoltage regulationisdonebycomparinga part of the output voltage (resistor bridge R6, R7 and P1) to the voltagereference(1.24V).
If this part is higher than 1.24V, the output of the voltageloop operationalamplifierdecreases.
5/15
TSM101/A
Figure 2 : SMPSUsing a TL431as VoltageController
The optocoupler current increases and tends to reduce the output voltage by the way of the PWM controller.
By enablingtheTSM101currentsource(pin2) itis possible tooffset the current sensing by a voltage equal to :
# R4* Io with Io=1.4mA
V
off
This offset lowers the output charge current and this function can be used to charge two types of batteries having different capacities. The current sourceis enabledby connecting pin 2 to ground
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 inputisput to ground), allowingthe charge of two differenttypes of batteries.
3.1 - Voltagelimitation
The end-of-chargevoltageis limited at 1.45V/cell, this is the recommended voltage for an ambient temperatureat 25
o
C.
A diode is generally inserted at the output of the chargerto avoid the discharge of thebattery if the charger is not powered. This diode is sometimes directly integrated in the battery pack. The influ-
ence of this diode on the charge is negligibleif the voltagedrop(0.7V)is takenintoaccount duringthe designof the charger.
The voltage at the output of thecharger is :
out
R6+R7
=
R6
xV
r
V and regardingR6 and R7 :
V
R6 =(
ref
V
) xR7
ref
V
out
P1, which is a part of R6 and R7 is not considered in thisequation.
The following values are used on the application board :
R7 = 12k
R6 = 1k
P1 = 220, adjust for V
= 15.2V with the
output
batteryreplaced by a 1kresistor
R10 = short circuit
C3 = 100nF
3.2 - Currentregulation
R5 isthe senseresistorusedforcurrent measure­ment.
6/15
TSM101/A
The currentregulationiseffectivewhenthe voltage drop across R5 is equal to the voltageon pin 5 of the TSM101 (assuming that the internal current sourceis disabled).
For mediumcurrents (<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.
V
R5 =
r5
, R5 = 0.285(four 1.2resistor in
I
ch
parallel)
R2 and R3 can be chosen using the following formula :
(V
Vr5)
R2 = R3
ref
x
V
r5
CHARGECONTROL
Ifthepin2isleftopen,thechargecurrentisnominal at # 700mA.
If pin 2 is connectedto ground,the internalcurrent source is enabled, the current measurement is off-settedby a voltageequal to :
V
x R4 withIo =1.4mA
r4=Io
This can be used to lower the charging current or eventuallyto stop thecharge, if V
r4>Vr5
In our example, the current offsetis equal to 700­200mA= 500mA,representinga voltageoffset
=140mV across R4.
V
r4
The following values are used on the application board :
R5 = 4 *1.20.5W in parallel
R4 = 100
R2 = 1.2k
R3 = 220
R9 = short circuit
R1 = 10k
C2 = 100nF
C5 = 100nF
C1 = output capacitorof 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 representedin figure 3.
Figure3 : SMPSUsing the TSM101
7/15
TSM101/A
5 - IMPROVEMENT
5.1. High frequency compensation
Two R-C devices (R9 + C2 & R10 + C3)are used to stabilizethe regulationat high frequencies.
The calculation of these values is not easy and is a function of the transferfunction of the SMPS.
A guess value for the capacitors C2 and C3 is 100nF.
5.2. Powersupply for TSM101
In applicationsrequiringlow voltagebatterycharge or when the chargeris in currentregulation mode, the outputvoltagecanbe toolowtosupplycorrectly the TSM101.
Thesame problemoccurs whentheoutputisshort­circuited.
A solution to providea quasi constant supply volt­agetotheTSM101isshownatfigure4:anauxiliary
Figure4 : An AuxiliaryWinding for TSM101 Power Supply
winding is added at the secondary side of the transformer.
This winding is forward coupled to the primary winding,thevoltageacrossitisdirectlyproportional 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 powertheTSM101. Thisis necessarywith autoranging SMPS with wide input voltages, for example90 to240Vwithout switching. In standard SMPS with voltage range from 200 to 240VACor 100 to130VAC,this regulatorcan beremoved and replaced by the small power supply shown on figure 5 (Raux, Caux, D2).
TSM101/A
5.3. HigherPrecision for the VoltageControl
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 theend-of-charge voltage due tothe fact that the charging current value decreases drasti­callyduring thefinalphaseofthe batterycharging.
But in other applicationsneeding highest possible precision in voltage control, another connecting
Figure5 : PreciseOutputVoltage Control
schematic is possible for TSM101 as shown on figure 5.
In this schematic, the 0V reference is defined as the commonpoint 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%internalvoltagereferenceprecision) is requiredin such applications.
5.4. An exampleof applicationwhere the charging current is different accordingto the charging phase.
Thefollowingapplicationincludesaspecificrecom­mendationwhichrequiresthatthechargingcurrent shouldbefixedto Ich1 =800mAinnormalcharging conditions, and Ich2 = 200mA when the cell volt­age is below Vl=2.5Vto optimizethe 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) isusedtoactivatethe TSM101 internal current generator to offset the currentmeasurementthankstoR4, andthe second (C2)is used to switch the status LED off.Onfigure 6, thestatus signalis determinedby voltage meas­urement, this could as wellbe achieved by current measurement.
If V5 = 100mV is the maximum tolerable voltage drop through the sense resistor R5 during normal
9/15
TSM101/A
chargingconditions,thenthe followingcalculations apply :
Current Control :
R5 = V5 / Ich1 = 0.1 / 0.8 = 0.125 R5 = 125m V5 = Vref x R3 / (R2 + R3) with R2 + R3 ~ 12k
and Vref= 1.24V R3 = 1k,R2 =11.4k V5 = R4 x Io +R5 x Ich2, therefore,R4 = (V5- R5
x Ich2) / Io with Io = 1.4mA
Figure 6 : OptimizedChargingConditions
R4 = 53.6 Vref = Vl x R15 / (R14 + R15) with Vl = 2.5V and
R14 + R15~ 20k R15 = R14= 10k
Voltage Control :
Vref= Vh x R6 / (R6 + R7) with Vh = 6.5Vand R6 + R7 ~ 12k
R6 = 2.36k, R7 = 10k Vref= Vh R17 / (R16 + R17) R17 = 10kΩ, R16 =42kΩ
10/15
TSM101/A
EVALUATION BOARD - TECHNICALNOTE
TSM101 integrates in the same 8 pin DIP or SO package
one 1.24V precision voltagereference
two operationnalamplifiers
two diodes which impose a NORfunctionon the
outputsof the operationnalamplifiers
one currentsourcewhichcanbe activated/inhib­ited thanks to anexternal pin.
An immediate way to take advantage of the high integration and reliabilityof TSM101is to use it as a voltage and current controlleron power supplies secondary.Theapplication note AN896 describes precisely how to use TSM101 in anSMPS battery charger.
The TSM101EvaluationBoardis adaptableto 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 TSM101EVALUATION BOARD ?
The generic Electrical Schematic is shown on fig­ure 1. It represents an incomplete SMPS power supplywhere the primary side is simplified.
The ”IN+”and ”IN-” power inputs of the evalu- ation board should be connected directly to the power lines of thepower supplysecondary.
The”Vcc” input of the evaluationboard should be connectedto 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 connectedto the baseof thedarlington to regulate the poweroutput.
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 choiceof the resistorbridge R6/R7 (and thetrimmer P1) due to equation1 :
Vref = R6/(R6+R7)xVout eq1
where Vref = 1.24V
Figure1
11/15
TSM101/A
The current control is given by the choice of the voltage drop through the sense resistor R5 (to be linkedtothenominalcurrentoftheapplication)and by the valueof thesense resistor itself.
For medium currents (< 1A), a good value for the voltage drop through R5 can be Vsense = 200mV (dissipation< 200mW).
TheresistorbridgeR2/R3shouldbechosenfollow­ing equation2 :
Vsense = R3/(R2+R3)xVref eq2
The totalvalue of the resistor bridge should be in the range of the kin order to ensure a proper chargeforthe voltagereference(in therangeofthe mA).
Tosetthecurrentlimit,thesenseresistorR5should be chosen following equation 3 :
Ilim = Vsense/R5 eq3
The internal current generator (Isce) can be used to offset the currentlimitation with a lower value.
This current generator is activated by connecting pin 2 to ground. Itis 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 currentlimitcalculatedintheprevious paragraph,and Ilim2 isthe currentlimitthatistobe 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 b ypass capacitors used to
smoothen the regulatedoutputs. C2 and C3are capacitorsused for highfrequency
compensation.
Table 1
Voltage /
Current Control
R1 10k 10k 10k R2 1.2k 1.2k 1.2k R3 220 220 220 R4 100 68 68 R5 1.2x4 0.8x4 1x1 R6 1k 1k 1k R7 12k 8.2k 5.6k P1 100 100 100 2 straps 0 0 0 C2 100nF 100nF 100nF C3 100nF 100nF 100nF C4 10µF22µF 4.7µF C5 100nF 100nF 100nF
15V 700mA 200mA
12V
1A
500mA
8.2V 200mA 100mA
Figure2representsinrealdimensionsthePCBand the silkscreen of the TSM101Evaluationboard.
Figure2
EXAMPLESOF COMPONENTLISTS
Table 1 summerizesafewexamplesof component lists to generate quickly 15V/700mA/200mA, 12V/1A/500mAor8.2V/200mA/100mAvoltageand current regulations.
12/15
PACKAGE MECHANICALDATA
8 PINS- PLASTICDIP
TSM101/A
Dim.
A 3.32 0.131
a1 0.51 0.020
B 1.15 1.65 0.045 0.065
b 0.356 0.55 0.014 0.022
b1 0.204 0.304 0.008 0.012
D 10.92 0.430 E 7.95 9.75 0.313 0.384
e 2.54 0.100 e3 7.62 0.300 e4 7.62 0.300
F 6.6 0260
i 5.08 0.200 L 3.18 3.81 0.125 0.150 Z 1.52 0.060
Min. Typ. Max. Min. Typ. Max.
Millimeters Inches
13/15
TSM101/A
PACKAGE MECHANICALDATA
8 PINS- PLASTICMICROPACKAGE (SO)
Dim.
A 1.75 0.069 a1 0.1 0.25 0.004 0.010 a2 1.65 0.065 a3 0.65 0.85 0.026 0.033
b 0.35 0.48 0.014 0.019
b1 0.19 0.25 0.007 0.010
C 0.25 0.5 0.010 0.020 c1 45
D 4.8 5.0 0.189 0.197
E 5.8 6.2 0.228 0.244
e 1.27 0.050
e3 3.81 0.150
F 3.8 4.0 0.150 0.157
L 0.4 1.27 0.016 0.050 M 0.6 0.024 S8
Min. Typ. Max. Min. Typ. Max.
Millimeters Inches
o
(typ.)
o
(max.)
14/15
PACKAGE MECHANICAL DATA
8 PINS -THIN SHRINK SMALLOUTLINEPACKAGE
TSM101/A
Dim.
Min. Typ. Max. Min. Typ. Max.
Millimeters Inches
A 1.20 0.05
A1 0.05 0.15 0.01 0.006 A2 0.80 1.00 1.05 0.031 0.039 0.041
b 0.19 0.30 0.007 0.15
c 0.09 0.20 0.003 0.012 D 2.90 3.00 3.10 0.114 0.118 0.122 E 6.40 0.252
E1 4.30 4.40 4.50 0.169 0.173 0.177
e 0.65 0.025
k0
o
o
8
o
0
o
8
l 0.50 0.60 0.75 0.09 0.0236 0.030
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15/15
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