1/13
■1.24V SERI ES VOLTAGE REFERENC E
WITH 10mA OU TPUT CURRENT AND 1%
PRECISION (TSM101A)
■TWO OPERA TIONAL AMPLIFIERS WITH
ORED OUTPUT AND 1M HZ GAIN BAND-
WIDTH PRODUCT
■BUILT-IN CURRENT GENERATOR WITH
ENABL E/DISABLE FUNCTION
■4.5 TO 32V SUPPLY VOLTAGE RANGE
■SO8 AND DIP8 PACKAGES
DESCRIPTION
The TSM101/TS M 101A integrated circuit incorpo-
rates a high stability ser ies band gap voltage refer-
ence, two O Red operational a mplifiers and a cur-
rent source.
This IC compares the DC voltage an d 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 out-
put current.
It can be used in every types of application requir-
ing a precision voltage regulation and current limi-
tation.
Other applications include voltage supervisors,
over voltage protection.. .
ORDER CODE
N = Dual in Line Package (DIP)
D = Small Outline Package (SO) - also available in Tape & Reel (DT)
PIN CONNECTIONS (top view)
Part Number Temperature
Range Package
ND
TSM101C/AC -20°C, +80°C ••
TSM101 I/AI -40°C, +105 °C ••
D
SO8
(Plastic Micropackage)
N
DIP8
(Plastic Package)
1
2
3
4
8
5
6
7
Vref
TSM101/A
VOLTAGE AND CURRENT CONTROLLER
June 2001
TSM101/A
2/13
ABSOLUTE MAXIMUM RATINGS
OPERATING CONDITIONS
ELECTRICAL CHA RACTERISTICS
Tamb = 25°C, VCC = 15V (unless otherwise specified)
OPERATIONAL AMPLIFIER: TSM101C/I/AC/AI
Symbol Parameter Value Unit
VCC DC supply Voltage1)
1. All voltages values, except differ ential voltage ar e with respect to network ground term inal.
36 V
Iout Output Current2)
2. The voltage reference is not protected against permanent short circuit.
20 mA
PdPower Dissipation 200 mW
Vin Input Voltage3)
3. The magnitude of input and output voltages must never exceed -0.3V or VCC -1.5V.
-0.3, VCC -1.5 V
Iout Input Current ±1 mA
Tstg Storage Temperature -40 to +125 °C
TjMaximum Junction Temperature 150 °C
Tthja Thermal Resistante Junction to Ambiant 130 to 200 °C/W
Symbol Parameter Value Unit
VCC Supply Voltage 4.5 to 32 V
Toper Operating Free Air Temperature Range Tmax to Tmin
Symbol Parameter Min. Typ. Max. Unit
ICC Total Supply Current
VCC = 1.5V 2mA
ViInput Voltage Range 0 VCC - 1.5V V
Vio
Input Offset Voltage
25°C
Tmin. ≤ Tamb ≤ Tmax. -5
-7 15
7mV
Iib
Input Bias Current
@ Vin =1.2V on pin and Vin =0V on pin 5
25°C
Tmin. ≤ Tamb ≤ Tmax.
-700
-1000 -300 0
0
nA
Isink
Output Sink Current, Vol =2.5V
25°C
Tmin. ≤ Tamb ≤ Tmax. 815 mA
Avo
Large Signal Voltage Gain
RL =2kΩ
Tmin. ≤ Tamb ≤ Tmax. 15 V/m
V
SVR Supply Voltage Rejection Ratio
Tmin. ≤ Tamb ≤ Tmax. 65 90 dB
CMR Common Mode Rejection Ratio
Tmin. ≤ Tamb ≤ Tmax. 80 dB
GBP Gain Bandwith Product
Vcc =15V, F = 100kHz
Vin = 10mV, RL = 2kΩ, CL = 100pF 1 MHz
Io
Output Leakage Current
25°C
Tmin. ≤ Tamb ≤ Tmax. 2
7µA
TSM101/A
3/13
ELECTRICAL CHARACTERISTICS
Tamb = 25°C, VCC = 15V (unless otherwise specified)
VOLTAGE REFERENCE : TSM101
VOLTAGE REFERENCE : TSM101A
CURRENT G ENERATOR: TSM101, T SM101A
Symbol Parameter TSM101C TSM101I Unit
Min. Typ. Max. Min. Typ. Max.
Vref Reference Voltage
Iout = 1mA, Tamb = 25°C 1.21 1.24 1.27 1.21 1.24 1.27 V
Kvt Temperature Stability
Tmin ≤Tamb ≤ Tmax 30 100 35 120 ppm/°C
Reglo Load Regulation
1 < Iout < 10mA 515 515mV
Regli Line Regulation
5 < Vin < 32V 3.5 10 3.5 10 mV
Symbol Parameter TSM101AC TSM101AI Unit
Min. Typ. Max. Min. Typ. Max.
Vref Reference Voltage
Iout = 1mA, Tamb = 25°C 1.227 1.24 1.252 1.227 1.24 1.252 V
Kvt Temperature Stability
Tmin ≤Tamb ≤ Tmax 30 100 35 120 ppm/°C
Reglo Load Regulation
1 < Iout < 10mA 515 515mV
Regli Line Regulation
5 < Vin < 32V 3.5 10 3.5 10 mV
Symbol Parameter TSM101C/AC TSM101I/AI Unit
Min. Typ. Max. Min. Typ. Max.
IoCurrent Source 1.4 1.4 mA
Kcgt Temperature Stability
Tmin ≤Tamb ≤ Tmax 500 600 ppm/°C
Cglir Line Regulation
4.5 < Vcc< 32V 0.003 0.03 0.003 0.03 mA
Vcsen Voltage at the enable pin to have
Io = 1.4mA
Tmin ≤Tamb ≤ Tmax 0.6 0.6
V
Vcsdis Voltage at the enable pin to have
Io = 0mA
Tmin ≤Tamb ≤ Tmax 22
V
I
csen Input Current on the Csen pin
Tmin ≤Tamb ≤ Tmax 30 30 µA
Icsleak Leakage Current
Vcs = 2V
Tmin ≤Tamb ≤ Tmax 0.5 2 0.5 2
µA
TSM101/A
4/13
DESCRIPTION
Name Pin Type Function
Vref 1 OUTPUT Voltage Reference Output 1.24V, 10mA max. Do not short circuit
Vrin 7 INPUT Voltage Regulation Loop input
Crin 5 INPUT Current Limitation Loop Input, connected to the sense resisto
Crref 3 INPUT Current Limitation Reference Input
Csen 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 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 32V DC)
GND 4 INPUT Ground
5/13
Th i s te c hn i ca l no t e sh ows how t o us e t h e TSM 10 1
integrated circuit with a switching mode power
supply (SMPS) t o realize a battery charger.
An example of realization of a 12V Nickel-cadmi-
um battery charger is given.
1 - TSM101 PRESENTATION
The TSM101 integrated circuit incorporates a high
stability series band gap voltage reference, two
ORed operat ional amplifiers and a current source
(Figure 1)
Fi gure 1 : TSM101 Schematic Diagram
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.
A gr eat majority of low or medium end power sup-
plies is voltage regulated by using shunt program-
mabl e 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 cur rent depending on t he dif-
ference between the actual output voltage and the
des ired one.
A current limitation is used to protect the power
supply against short circuits, but lacks precision.
This limitat ion is general ly realized by sens ing the
current of the power transistor, in the primary side
of t he SMPS.
The role of the T SM10 1 is to make a f ine regu la-
tion of the output current of the S MPS and a pre-
cise voltage limitat ion.
The primary current limitation is conserved and
acts as a security for a fail-safe operation if a
sho rt-circuit occurs a t the output of th e charger.
2 - PRINCIPLE O F OPERATION
The curren t regulation loop and the voltage limit a-
tion loop use an internal 1.24V band-gap vo lta ge
reference. This voltage ref erence has a good pre-
cision (better than 1.5%) and exhibits a very stable
temperat ure behavior.
The current limitation i s performed by sensi ng t he
voltage across the low ohmic value resistor R5
and comparing it t o 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 in-
creases and t ends 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 amplifi er decreases.
1
2
3
4
8
5
6
7
Vref
APPLICATION NOTE
A BATTERY CHARGER USING THE TSM101
TSM101/A
6/13
Figure 2 : SMPS Using a TL431 as Voltage Controller
The optocoupler current increases and tends to
reduce the out put voltage by t he way of the P WM
controller.
By enabling the TSM101 cu rrent source (pi n 2) it
is pos sible to offset the current se nsing by a volt -
age equal to :
Voff # R4 * Io wi th I o = 1.4 mA
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
3 - CALCULATION OF THE ELEMENTS
The charge current is regulated at 700mA (if the
charge control input is left open) or 200m A (if the
charge control input is put to ground ), all owing the
charge of two different types of batteries.
3.1 - Voltage limitation
The end-of- charge voltage is li mited 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 p owered. This diode is sometimes
directly integrated in the battery pack. The influ-
ence of this diode on the c harge 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 :
• Vout =
and regarding R6 and R7 :
• R6=
P1, which is a part of R6 and R7 is not considered
in this equation.
The following values are used on the application
board :
• R7 = 1 2kΩ
• R6 = 1 kΩ
• P1 = 220Ω, adjust for Voutput = 15.2V with the
battery replaced by a 1kΩ re si sto r
• R10 = short circuit
• C3 = 100nF
3.2 - Current regulation
R5 is the sense res istor us ed for current measure-
ment.
The current regulation is effective when the volt-
age drop across R5 is equal to the voltage on pin
5 of the TSM101 (assuming that the internal cur-
rent source is disabled).
For medium currents (<1A), a voltage drop across
R5 of 200mV = Vr5 is a good value, R5 can be re-
alized with standard low cost 0.5W resistors in
parallel.
• R5 = , R5 = 0 .285Ω (four 1.2Ω re sisto r in
parallel)
R2 and R3 can be chos en using th e following f or-
mula :
• R2 =
CHARGE CONTROL
If the pin 2 is left open, the charge current is nom-
inal at # 700mA.
R6 R7+
R6
---------------------- Vr
×
Vref
Vout Vref–
--------------------------------
R7
×
Vr5
Ich
----------
R3 Vref Vr5–
Vr5
----------------------------
×
TSM101/A
7/13
If pin 2 is connected to ground, the int ernal current
source is enabled, the current measurement is
off-se tted by a voltage equal to :
• Vr4 = Io x R4 with Io = 1.4mA
This can be us ed to lower the chargin g current or
eve ntually to stop the charge, if Vr4 > Vr5
In our example, the current offset is equal to 700 -
200m A = 500m A, represent ing a voltage offset
Vr4 = 140m V 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 = s hort circuit
• R1 = 10kΩ
• C2 = 100nF
• C5 = 100nF
• C1 = out put capacitor of the SMPS
• C4 = 10µF
4 - SCHEMATIC DIAGRAM
Figure 2 represent s a schema tic of the out put cir-
cuit of a “classical” SMPS using a TL431 for volt-
age regulation. This circuit is modified to use
theTSM101 and the final circuit is represented in
figure 3.
Fi gure 3 : SMPS Using the TSM1 01
5 - IMPROVEMENT
5.1. Hig h frequency compen sati on
Two R-C dev ices (R9 + C2 & R10 + C3) are used
to stabilize the regulation at high frequenci es.
The calculat ion 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.
5.2. Po wer su pply for TSM 101
In applications requiring low voltage battery
char ge or when the charger is in current regulation
mode, the output voltage can be too low to supply
correctly the TSM101.
The same problem occurs when the output is
short-circuited.
A solution to prov ide a quasi consta nt suppl y volt-
age to the TSM101 is shown at figure 4 : an auxil-
iary w inding is added at t he sec ondary s ide of the
transformer.
This winding is forward coupled to the primary
winding, the voltage across it is directly propor-
tional to the mains rectified voltage, even if t he fly-
bac k voltage is close to zero.
As this auxiliary winding is a voltage source, it is
nec essary to add a resist or (R11) on the catho de
of the rectifier (D3) to limit the current.
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
SMP S with voltage range from 200 to 240V AC 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
8/13
Fi gure 4 : An Aux iliary Winding fo r TSM 101 P o wer Su pply
5.3. Hig her Precisi on for the Volt age Contro l
The voltage drop through the sense resistor R5
offsets the voltage measurem ent. In most battery
charging applications, this offset is not taken into
account because the error is negligeable com-
pared to the end-of-ch arge voltage due to the fact
that the charging current value decreases drasti-
cally during the final phase of the battery charging.
But in other applicat ion s needing hig hest possibl e
precision in voltage control, another connecting
schematic is possible for TSM101 as shown on
figure 5.
Fi gure 5 : Precise Output Voltage Cont rol
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 brid ge
R6/R7, and the ground (pin 4) of the TSM101.
TSM101A (1% internal voltage reference preci-
sion) is required in such applicati ons.
TSM101/A
9/13
5.4. An exampl e of applicati on where the
charg ing cur rent is different accord ing to the
charg in g phase.
The following application includes a specific rec-
ommendation which requires that the charging
current should be fixed to Ic h1 = 800mA in normal
cha rging condition s, and I ch2 = 200m A when t he
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 sec-
ond (C2) is us ed to switch the s ta tus LED off. On
figur e 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 throug h the sense res isto r R5 duri ng normal
charging conditions, then the following calcula-
tion s 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
R4 = 53.6Ω
Vref = Vl x R1 5 / (R14 + R15) with Vl = 2.5V a nd
R14 + R15 ~ 20kΩ
R15 = R14 = 10kΩ
Voltage Control :
Vref = Vh x R6 / (R6 + R7) with Vh = 6.5V and
R6 + R7 ~ 12kW
R6 = 2.36kW, R7 = 10kW
Vref = Vh R17 / (R16 + R17)
R17 = 10k W, R16 = 42kW
Vol tage Control :
Vref = Vh x R6 / (R6 + R7) with Vh = 6.5V and
R6 + R7 ~ 12kW
R6 = 2.36kW, R7 = 10kW
Vref = Vh R17 / (R16 + R17)
R17 = 10k W, R16 = 42kW
Fi gure 6 : Optim ized Charging Cond itions
10/13
TSM101 integrates in the same 8 pin DIP or SO
package
• one 1.24V precision voltage reference
• two operationnal amplifiers
• t wo diodes which impos e a NOR function on the
outpu ts of the operationnal amplifiers
• one current source which can be activated/ in-
hibited tha nks to an external pin.
An immediate way to take advantage of the high
integration and reliability of TSM101 is t o use it as
a voltage and current controller on power supplies
secondary. The application note AN896 descr ibes
prec isely how to use TSM101 in an SMPS battery
charger.
The TSM101 Evaluation Board is adaptable t o any
power s upply or battery charger (SMPS or linear)
as a voltage and current controller with minimal
con straints from the user.
HOW TO USE THE TSM1 0 1 EVAL U A TION
BOARD ?
The gene ric Electrical Schema tic is shown on f ig-
ure 1. It represents an incomplete SMPS power
supply where the primary side is simpli fied.
The “ IN+”a nd “IN-” power i nputs of th e eval ua-
tion board should be connected directly to the
power lines of t he power supply secondary.
The “Vcc” input of the evaluation board should
be connected to the auxiliary supply line.
In the ca se of an SMPS power supply, the “Reg”
outpu t of the evaluation board s hould be conne ct-
ed to the Optocoupler input to regul ate the PWM
block in the primary side. In the case of a linear
power supply, the “Reg” output should be con-
nect ed to the base of the darlington to regulate the
power output.
A diode might be needed on the output of the eval-
uation board in the case of a battery charger appli-
cation to avoid the discharge of the battery when
the charger is not connected.
COMP ONENTS CALCULATIONS
The voltage co ntrol is given by the choice of the
resistor bridge R6/R7 (and t he trimmer P1) due to
equat ion 1 :
• Vref = R6/(R6+R7)xVout eq1
where Vref = 1.24V
Fi gure 1
EVALUATION BOARD -TECHNICAL NOTE
TSM101/A
11/13
The cur rent control is given by the choice of the
voltag e drop throu gh the sense resistor R5 (to be
linked to the nominal current of the application)
and by the value of the sense resistor itself.
For m edium currents (< 1A ), a good value f or the
voltag e drop throu gh R5 can be V sens e = 200m V
(dissipati on < 200m W).
The resistor bridge R2/R3 should be chosen fol-
lowing equa tion 2 :
• Vsense = R3/(R2+R3)xVref eq2
The t otal value of the resistor bridg e should be i n
the range of the kW 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
sho uld be chosen following equa tion 3 :
• Ilim = Vsense/R5 eq3
The in ternal 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 inhib ited if pin 2 is connect ed
to the positive rail via the pull up resistor R1.
The current offset is given by the choice of the re-
sistor R4.
If Ilim1 is the current limit calculated in the previ-
ous paragraph, and Ilim2 is the current limit that is
to be set when pin 2 is connected to ground, R4
sho uld be chosen following equa tion 4 :
• R4 = (Vsense - Ilim2xR5)/Isce eq4
where Isce = 1.4mA
C4 and C5 are bypass capacitors used to smooth-
en the regulated output s.
C2 and C3 are capacitors used for high frequency
compensation.
EXAMPLES OF COMPO NENT LISTS
Table 1 summerizes a few examples of compo-
nent lists to gen erate qui ckly 15V/700mA /20 0mA,
12V/1A/500mA or 8.2V/200mA/100mA voltage
and current regulations.
Fi gure 2
Voltage/
Current
Control
15V
700mA
200mA
12V
1A
500mA
8.2V
200mA
100mA
R1 10kΩ10kΩ10kΩ
R2 1.2kΩ1.2kΩ1.2kΩ
R3 220kΩ220kΩ220kΩ
R4 100Ω68Ω68Ω
R5 1.2Ω x 4 0.8Ω x 4 1Ω x 1
R6 1kΩ1kΩ1kΩ
R7 12kΩ8.2kΩ5.6kΩ
P1 100Ω100Ω100Ω
2 straps 0Ω0Ω0Ω
C2 100nF 100nF 100nF
C3 100nF 100nF 100nF
C4 10µF22
µ
F4.7
µ
F
C5 100nF 100nF 100nF
TSM101/A
12/13
PACKAGE MECHANICAL DATA
8 PINS - PLASTIC DIP
Dim. Millimeters Inches
Min. Typ. Max. Min. Typ. Max.
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
TSM101/A
13/13
PACKAGE MECHANICAL DATA
8 PINS - PLASTIC MICROPACKAGE (SO)
Dim. Millimeters Inches
Min. Typ. Max. Min. Typ. Max.
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° (typ.)
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
S 8° (max.)
b
e3
A
a2
s
L
C
E
c1
a3
b1
a1
DM
85
14
F
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