ST TSM1052 User Manual

Constant voltage and constant current controller

Features

■ Secondary-side constant voltage and constant

current control

■ Very low voltage operation

■ Very low quiescent consumption

■ High-accuracy internal reference

■ Low external component count

■ Wired-or open-drain output stage

■ Easy frequency compensation

■ SOT23-6 micro package

Applications

TSM1052

for battery chargers and adapters

SOT23-6

■ Battery chargers

■ AC DC adapters

Description

The TSM1052 is a highly integrated solution for SMPS applications requiring a dual control loop to perform CV (constant voltage) and CC (constant current) regulation.

The TSM1052 integrates a voltage reference, two op amps (with OR-ed open-drain outputs), and a low-side current sensing circuit.

The voltage reference, along with one op amp, is the core of the voltage control loop; the current sensing circuit and the other op amp make up the current control loop.

Table 1. Device summary

Part number Package Packaging

TSM1052 SOT23-6 Tape and reel

The external components needed to complete the two control loops are:

■ A resistor divider that senses the output of the

power supply (adapter, battery charger) and fixes the voltage regulation set point at the specified value;

■ A sense resistor that feeds the current sensing

circuit with a voltage proportional to the dc output current; this resistor determines the current regulation set point and must be adequately rated in terms of power dissipation;

■ Frequency compensation components

(RC networks) for both loops.

The TSM1052, housed in one of the smallest package available, is ideal for space-shrunk applications such as adapters and chargers.

February 2008 Rev 2 1/15

www.st.com

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Contents TSM1052

Contents

1 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

1.1 Pin connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

1.2 Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

1.3 Internal schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

1.4 Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

1.5 Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

3 Typical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

4 Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

4.1 Typical application schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

4.2 Voltage and current control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

4.2.1 Voltage control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

4.2.2 Current control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

4.3 Compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

4.4 Start up and short circuit conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

5 Mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

6 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

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TSM1052 Description

1 Description

1.1 Pin connection

Figure 1. Pin Connection (top view)

6

Vctrl

1

6

Vcc

1.2 Pin description

Table 2. Pin description

N. Name Function

1V

2GND

3OUT

4I

5V

ctrl

sense

GND

OUT

Inverting input of the voltage loop op amp. The pin will be tied to the mid-point of a resistor divider that senses the output voltage.

Ground. Return of the bias current of the device. 0 V reference for all voltages. The pin should be tied as close to the ground output terminal of the converter as possible to minimize load current effect on the voltage regulation set point.

Common open-drain output of the two internal op amps. The pin, able to sink current only, will be connected to the branch of the optocoupler’s photodiode to transmit the error signal to the primary side.

Non-inverting input of the current loop op amp. It will be tied directly to the hot (negative) end of the current sense resistor

Inverting input of the current loop op amp. The pin will be tied to the cold end of the current sense resistor through a decoupling resistor.

2

3

5

4

Vsense

Ictrl

Supply Voltage of the device. A small bypass capacitor (0.1 µF typ.) to GND,

6Vcc

located as close to IC’s pins as possible, might be useful to get a clean supply voltage.

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Description TSM1052

1.3 Internal schematic

Figure 2. Internal schematic

Vcc

6

1.21 V

1.238 V

+

200 mV

VsenseIctrl

6

+

-

+

-

54

OUT

3

Vctrl

1

GND

2

1.4 Absolute maximum ratings

Table 3. Absolute maximum ratings

Symbol Pin Parameter Value Unit

V

CC

V

OUT

I

OUT

V 1, 4, 5 Analog inputs -0.3 to 3.3 V

1.5 Thermal data

Table 4. Thermal data

Symbol Parameter Value Unit

R

T

thJA

OP

max

STG

Thermal resistance, junction-to-ambient 250 °C/W

Junction temperature operating range -10 to 85

Maximum junction temperature 150

Storage temperature -55 to 150

6 DC supply voltage -0.3 to 20 V

3 Open-drain voltage -0.3 to V

3 Max sink current 100 mA

CC

V

°CTj

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TSM1052 Electrical characteristics

2 Electrical characteristics

TJ = 25 °C and VCC = 5 V, unless otherwise specified

Table 5. Electrical characteristics

Symbol Parameter Test conditions Min Typ Max Unit

Device supply

V

Voltage operating range 1.7 18 V

CC

Quiescent current

I

(Ictrl = Vsense = Vctr = 0,

CC

OUT = open)

Voltage control loop op amp

Gm

Vref Voltage reference

Transconductance

v

(sink current only)

(2)

(3)

Ibias Inverting input bias current

Current control loop

Gm

Vsense

Ibias

Transconductance

i

(sink current only)

(4)

Current loop reference @ I(Iout) = 1 mA

Non-inverting input source current @ V(Ictrl) = -200 mV

(5)

(1)

150

µA

300

13.5 S

2.5

1.198 1.21 1.222 V

1.186 1.234

50

nA

100

1.5 7 S

196 200 204

mV

192 208

20

µA

40

Output stage

100

V

OUTlow

1. Specification referred to -10 °C < TA < 85 °C

2. If the voltage on Vctrl (the negative input of the amplifier) is higher than the positive amplifier input

3. The internal Voltage Reference is set at 1.21 V (bandgap reference). The voltage control loop precision

4. When the positive input at Ictrl is lower than -200 mV, and the voltage is decreased by 1mV, the sinking

5. The internal current sense threshold is set at -200 mV. The current control loop precision takes into

Low output level @ 2 mA sink current

(Vref = 1.21 V), and it is increased by 1mV, the sinking current at the output OUT will be increased by

3.5 mA.

takes into account the cumulative effects of the internal voltage reference deviation as well as the input offset voltage of the transconductance operational amplifier. The internal Voltage Reference is fixed by bandgap, and trimmed to 0.5% accuracy at room temperature.

current at the output Out will be increased by 7 mA.

account the cumulative effects of the internal voltage reference deviation as well as the input offset voltage of the transconductance operational amplifier.

(1)

200

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mV