TSM1012ID - STMicroelectronics - Datasheet.Directory

1/8

■CONSTANT VOLTAGE AND CONSTANT

CURRENT CONTROL

■LOW CONSUMPTION

■LOW VOLTAGE OPER AT ION

■LOW EXTERNAL COMPONENT COUNT

■CURRENT SINK OUTPUT STAGE

■EASY COMPENSATION

■HIGH AC MAINS VOLTAGE REJECTI ON

VOLTAGE REFERENCE

■FIXED OUTPUT VOLTAGE REFERENCE

1.25V

■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 -

comm on co lle ctors) .

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

■ADAPTERS

■BATTERY CHARGERS

ORDER CODE

D = Small Outline Package (SO) - also available in Tape & Reel (DT

S = Small Outline Pack age (MiniSO8) - also available in Tape & Reel (ST)

PIN CONNECTIONS (top view)

Part

Number Temperature

Range Package Vref Marking

SD%

TSM1012I -40 to 105°C •1 M1012

TSM1012AI -40 to 105°C •0.5 M1012A

TSM1012I -40 to 105°C •1M804

TSM1012AI -40 to 105°C •0.5 M805

SO-8

(Plastic Package)

MiniSO-8

(Plastic Micropackage)

128V

Vref Vcc

CC-

CC+ Gnd

CV- CV+

Out

,25V

Februa ry 20 04

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 Ou tpu t Outp ut of the two ope ra tio na l amp lifie r

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 = 25°C and Vcc = +18V (unless otherwise specified)

Symbol Parameter Test Condition Min Typ Max Unit

Total Curre nt Cons um pt ion

Icc Total Supply Current, excluding current

in Voltage Reference1).

1. Test co nditions: 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 µA

Vz Vcc clamp voltage Icc = 50mA 28 V

Operators

Vio Input Offset Voltage

TSM1012

TSM1012A

Tamb = 25°C

Tmin. ≤ Tamb ≤ Tmax.

Tamb = 25°C

Tmin. ≤ Tamb ≤ Tmax.

0.5

DVio Input Offset Voltage Dri ft 7 µV/°C

Iio Input Offset Current Tamb = 25°C

Tmin. ≤ Tamb ≤ Tmax.

230

50 nA

Iib Input Bias Current Tamb = 25°C

Tmin. ≤ Tamb ≤ Tmax.

50 150

200 nA

SVR Supply Voltage Rejection Ration VCC = 4.5V to 28V 65 100 dB

Vicm Input Common Mode Voltage Range 0 Vcc-1.5 V

CMR Common Mode Rejection Ratio Tamb = 25°C

Tmin. ≤ Tamb ≤ Tmax.

60 85 dB

Output stage

Gm Transconduction Gain. Sink Current

Only2)

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 amp lifier, the sinking current at the output OUT will be increase d by Gm*1mA.

Tamb = 25°C

Tmin. ≤ Tamb ≤ Tmax. 0.5 1

1mA/mV

Vol Low outp ut vo ltage at 5 mA sin kin g

current Tmin. ≤ Tamb ≤ Tmax. 250 400 mV

Ios Output Short Circuit Current. Output to

(Vcc-0.6V). Sink Current Only Tamb = 25°C

Tmin. ≤ Tamb ≤ Tmax.

510 mA

Vo ltage refere nc e

Vref Reference Input Voltage

TSM1012 1% precision

TSM1012A 0.5% precision

Tamb = 25°C

Tmin. ≤ Tamb ≤ Tmax.

Tamb = 25°C

Tmin. ≤ Tamb ≤ Tmax.

1.238

1.225

1.244

1.237

1.25

1.262

1.273

1.256

1.261

∆Vref Reference Input V oltage Deviation Over

Temperature Range Tmin. ≤ Tamb ≤ Tmax. 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 abov e a ppl ic ati on sc hem ati c, t he TS M10 12 i s use d on the se con dar y si de of a f lybac k ada pter ( 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

Vref

CC-

CC+

CV-

CV+

1,25V

2 6

Rsense

optocoupler

secondary side

Cic1

2,2nF

Cvc1

2,2nF

Ric1

22K

Rvc1

22K

Rlimit

OUT+

OUT-

Ric2

PWM

controller

optocoupler

pri m ary side

TSM1012

28V

Vref

Vcc

CC-

CC+

Gnd

CV-

CV+

1,25V

2 6

47nF

5/8

1. Voltage and Current Control

1.1. Voltage Control

The vol tage loop is controlled via a first tr anscon-

ductanc e opera tional amplifier , the resis tor bridg e

R1, R2, and the optocoupler which is directly con-

nected to the output.

The relation between the values of R1 and R2

should be cho sen as written in Equ ati on 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 shoul d 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 br idge tie d to the Vref vol tage ref erence. Its

middle poi nt is tied to the posi tiv e inp ut of the cur-

rent c ont ro l ope rational a mpl ifi er , and i ts fo ot is t o

be connected to lower potential point of the sense

resistor as shown o n the follow ing figure. The re-

sistors of this bridge are matched to provide the

best prec is io n poss ib le

The control equation verifies:

Rsense x Ilim = Vsense eq2

Vsen se = 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 outpu t of the IC). This mak es an ORing func-

tion which ensures that whenever the current or

the vo ltage reac hes too high va lues, the opt ocou-

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 vo ltage-control trans-condu ctance operati on-

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.

Vout

Iout

Voltage regulation

Current r egulation

TSM1012 Vcc : independent power supply

0Secondary current regulation

TSM1012 Vcc : On power output

Primary current regulation

TSM1012

PRINCIPLE OF OPERATION AND APPLICATION HINTS

TSM1012

6/8

The current-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

Cic1=2.2nF and a resistor Ric1=22KΩ in series.

3. Start Up and Short Circuit Conditions

Under start-up or short-circuit conditions the

TSM1012 is not provided with a high enough sup-

ply voltage. This is due to the fact that the chip has

its power supply line in common with the power

supply line of the system.

Therefore, the current limitation can only be en-

sured by the prima ry PWM module, whic h should

be chosen accordingly.

If the primary current limitation is considered not to

be precise enough for the application, then a suffi-

cient supply for the TSM1012 has to be ensured

under any condition. It would then be necessary to

add some ci rcuitr y to suppl y the chi p with a sepa-

rate power line. This can be achieved in numerous

ways, including an additional winding on the trans-

former.

4. Voltage clamp

The following schematic shows how to realize a

low-cost power supply for the TSM1012 (with no

additional windings).Please pay attention to the

fact that in the particular case presented here, this

low-cost power supply can reach voltages as high

as twice the voltage of the regulated line. Since

the Absolute Maximum Rating of the TSM1012

supply voltage is 28V. In the aim to protect he

TSM1012 against such how voltage values a in-

ternal zener clamp is integrated.

Rlimit = (Vcc-Vz)Ivz

Figure 4 : Clamp voltage

Figure 5 :

28V

Vcc

Rlimit

Ivz

TSM1012

Rsense

optocoupler

secondary side

Cic1

2,2nF

Cvc1

2,2nF

Ric1

22K

Rvc1

22K

Rlimit

OUT+

OUT-

Ric2

PWM

controller

optocoupler

pri m ary side

TSM1012

28V

Vref

Vcc

CC-

CC+

Gnd

CV-

CV+

1,25V

2 6

47nF

TSM1012

7/8

PACKAGE MECHANICAL DATA

DIM. mm. inch

MIN. TYP MAX. MIN. TYP. MAX.

A 1.35 1.75 0.053 0.069

A1 0.10 0.25 0.04 0.010

A2 1.10 1.65 0.043 0.065

B 0.33 0.51 0.013 0.020

C 0.19 0.25 0.007 0.010

D 4.80 5.00 0.189 0.197

E 3.80 4.00 0.150 0.157

e 1.27 0.050

H 5.80 6.20 0.228 0.244

h 0.25 0.50 0.010 0.020

L 0.40 1.27 0.016 0.050

k ˚ (max.)

ddd 0.1 0.04

SO-8 MECHANICAL DATA

0016023/C

TSM1012

8/8

PACKAGE MECHANICAL DATA

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