STMicroelectronics TSM1052 User guide

TSM1052

Constant voltage and constant current controller for battery chargers and adapters

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

■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.

SOT23-6

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.

Table 1.	Device summary
	Part number	Package	Packaging
	TSM1052	SOT23-6	Tape and reel

February 2008

Rev 2

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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

1.1Pin connection

Figure 1. Pin Connection (top view)

Vctrl		1		6			Vcc
GND		2		5			Vsense
OUT		3		4			Ictrl

1.2Pin description

	Table 2.	Pin description
	N.	Name	Function
	1	Vctrl	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
	2	GND	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
	3	OUT	current only, will be connected to the branch of the optocoupler’s photodiode
			to transmit the error signal to the primary side.
	4	Ictrl	Non-inverting input of the current loop op amp. It will be tied directly to the hot
			(negative) end of the current sense resistor
	5	Vsense	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.
			Supply Voltage of the device. A small bypass capacitor (0.1 µF typ.) to GND,
	6	Vcc	located as close to IC’s pins as possible, might be useful to get a clean
			supply voltage.

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Description	TSM1052

1.3Internal schematic

Figure 2. Internal schematic

			Vcc
	1.21 V		6
	1.238 V	+	3	OUT
	+
		-
	200 mV	+	1	Vctrl
		-	2	GND
	4	5
	Ictrl	Vsense

1.4Absolute maximum ratings

Table 3.	Absolute maximum ratings
Symbol		Pin	Parameter	Value	Unit
VCC		6	DC supply voltage	-0.3 to 20	V
VOUT		3	Open-drain voltage	-0.3 to VCC	V
IOUT		3	Max sink current	100	mA
V		1, 4, 5	Analog inputs	-0.3 to 3.3	V

1.5Thermal data

Table 4.	Thermal data
Symbol		Parameter	Value	Unit
RthJA		Thermal resistance, junction-to-ambient	250	°C/W
TOP		Junction temperature operating range	-10 to 85
Tjmax		Maximum junction temperature	150	°C
TSTG		Storage temperature	-55 to 150

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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
VCC	Voltage operating range			1.7		18	V
	Quiescent current				150
ICC	(Ictrl = Vsense = Vctr = 0,						µA
			(1)			300
	OUT = open)
Voltage control loop op amp
Gmv	Transconductance			1	3.5		S
	(sink current only)	(2)
			(1)		2.5
Vref	Voltage reference (3)			1.198	1.21	1.222	V
			(1)	1.186		1.234
Ibias	Inverting input bias current				50		nA
			(1)		100
Current control loop
Gmi	Transconductance			1.5	7		S
	(sink current only) (4)
			(1)
Vsense	Current loop reference (5)			196	200	204	mV
	@ I(Iout) = 1 mA		(1)	192		208
Ibias	Non-inverting input source current @				20		µA
	V(Ictrl) = -200 mV		(1)		40
Output stage
VOUTlow	Low output level @ 2 mA sink current				100		mV
			(1)			200

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 (Vref = 1.21 V), and it is increased by 1mV, the sinking current at the output OUT will be increased by 3.5 mA.

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

4.When the positive input at Ictrl is lower than -200 mV, and the voltage is decreased by 1mV, the sinking current at the output Out will be increased by 7 mA.

5.The internal current sense threshold is set at -200 mV. The current control loop precision takes into account the cumulative effects of the internal voltage reference deviation as well as the input offset voltage of the transconductance operational amplifier.

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