ST AN3093 Application note

AN3093

Application note

ALTAIR05T-800 5 W wide range CV-CC optoless adapter demonstration board

1 Introduction

This application note describes the demonstration board of the all primary-sensing switching regulator ALTAIR05T-800 and presents the results of its bench evaluation. The board implements a 5 W (5 V / 1 A) wide range mains battery charger with constant voltage/constant current.

The ALTAIR05T-800 combines a high-performance low-voltage PWM controller chip and an 800 V, avalanche rugged power MOSFET in the same package.

The PWM chip is a quasi-resonant (QR) current mode controller IC specifically designed for QR ZVS (zero-voltage switching at switch turn-on) flyback converters.

The device is capable of providing constant output voltage (CV) and constant output current (CC) regulation using primary sensing feedback. This eliminates the need for the optocoupler, the secondary voltage reference, as well as the current sensor, while maintaining very accurate regulation.

Additionally, it is possible to compensate the voltage drop of the output cable, so as to improve CV regulation on the externally accessible terminals.

Extremely low consumption under no-load conditions is ensured thanks to a controlled burst mode operation that, along with the built-in high-voltage startup circuit and the low operating current of the device, helps minimize residual input consumption. Although an auxiliary winding is required in the transformer to correctly perform CV/CC regulation, the chip is capable of powering itself directly from the rectified mains. This is useful especially during CC regulation, where the flyback voltage generated by the winding drops. However, if ultra low no-load input consumption is required to comply with the most stringent energy saving recommendations, then the device needs to be powered via the auxiliary winding.

Figure 1. Demonstration board picture

January 2011

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Contents	AN3093

Contents

1	Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		. 1
2	Test board: design and evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		5
3	Efficiency and no-load measurements . . . . . . . . . . . . . . . . . . . . . . . . .		11
	3.1	Standby optimization: tips for reducing standby consumption . . . . . . . . .	12
		Design optimization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	13
	3.2	Five star charger energy rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	14
4	Typical board waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		15
5	V-I output characteristics and cable drop compensation . . . . . . . . . .		19
6	Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		22
Appendix A Modes of operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .			23
	A.1	Constant voltage operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	23
	A.2	Constant current operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	24
	A.3	Current comparator speed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	25
	A.4	Cable drop compensation block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	26

Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

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AN3093	List of tables

List of tables

Table 1. ALTAIR05T-800 demonstration board: electrical specification . . . . . . . . . . . . . . . . . . . . . . . 5 Table 2. ALTAIR05T-800 demonstration board: bill of material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Table 3. ALTAIR05T-800 demonstration board: transformer characteristics . . . . . . . . . . . . . . . . . . . 9

Table 4. Efficiency at 115 VAC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Table 5. Efficiency at 230 VAC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Table 6. Standby consumption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Table 7. Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

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List of figures	AN3093

List of figures

Figure 1.	Demonstration board picture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . . . . . .	. 1
Figure 2.	Electrical schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . . . . . .	. 6
Figure 3.	PCB: top side and through-hole components(1) . . . . . . . . . . . . . . . . . . .	. . . . . . . . . . . . . .	. 8
Figure 4.	PCB: bottom side and SMD components(1) . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . . . . . .	. 8
Figure 5.	Electrical schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . . . . . .	. 9
Figure 6.	Side view . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . . . . . .	. 9
Figure 7.	Bottom side view. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . . . . . .	10
Figure 8.	PCB hole dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . . . . . .	10
Figure 9.	Efficiency vs. output power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . . . . . .	12
Figure 10.	No-load consumption score chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . . . . . .	14
Figure 11.	Normal operation at full load, at 115 VAC and 230 VAC . . . . . . . . . . . . .	. . . . . . . . . . . . . .	16
Figure 12.	Normal operation in CC mode with VOUT = 3 V, at 115 VAC and 230 VAC . . . . . . . . . . . . .		16
Figure 13.	Short-circuit at 115 VAC and 230 VAC . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . . . . . .	17
Figure 14.	Normal operation at no-load, at 115 VAC and 230 VAC . . . . . . . . . . . . .	. . . . . . . . . . . . . .	17
Figure 15.	Startup at no-load, at 115 VAC and 230 VAC . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . . . . . .	18
Figure 16.	Startup at full load, at 115 VAC and 230 VAC . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . . . . . .	18
Figure 17.	Output characteristic at 115 VAC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . . . . . .	19
Figure 18.	Output characteristic at 230 VAC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . . . . . .	20
Figure 19.	Output characteristic without cable drop compensation: RCABLE = 0.32	Ω
	and R5 = 10 kΩ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . . . . . .	20
Figure 20.	Output characteristic with cable drop compensation: RCABLE = 0.32 Ω
	and R5 = 10 kΩ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . . . . . .	21
Figure 21.	Voltage control principle: internal schematic . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . . . . . .	23
Figure 22.	Current control principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . . . . . .	24
Figure 23.	Constant current operation: switching cycle waveforms . . . . . . . . . . . . .	. . . . . . . . . . . . . .	25
Figure 24.	Feed-forward compensation: internal schematic . . . . . . . . . . . . . . . . . .	. . . . . . . . . . . . . .	26
Figure 25.	CDC compensation: external configuration . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . . . . . .	27

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AN3093	Test board: design and evaluation

2 Test board: design and evaluation

A 5 W battery charger demonstration board based on ALTAIR05T-800 is now presented.

Table 1 summarizes the electrical specifications of the application. Table 2 provides the bill of materials and Table 3 lists the transformer specifications. The electrical schematic is shown in Figure 2 and the PCB layout in Figure 3 and Figure 4.

Table 1.	ALTAIR05T-800 demonstration board: electrical specification
	Parameter					Value
Input voltage range (VIN)						90 - 265 VAC
Mains frequency (fL)						50 - 60 Hz
Maximum (rated) output power						5 W
						VOUT = 5 V ± 5%
Output						IOUT = 0 to 1 A ± 7%
						Vripple < 100 mV
Minimum switching frequency in normal mode						70 kHz
Target average efficiency (at P		OUT	= 5 W, V	IN	= 90 - 264 V )	> 70%(1)
					AC
Maximum input power in standby						< 100 mW(2)

1.Compliant with the EPA 2.0 standard for low voltage devices (VOUT < 6, IOUT > 0.55 A).

2.Compliant with the European Code of Conduct, adapter for mobile handheld battery-driven applications, starting from 1st January 2011.

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Figure 2. Electrical schematic

					L1				T1	D7	5 V - 1 A
		BR		470 µH						STPS3L40UF
AC IN	R1	MB6S-RC						C3	R2
					C1		C2				C8
								1 nF		R9
					4.7 µF		4.7 µF				1000 µF
AC IN	1 W				400 V		400 V				low ESR
								D7
								STTH1L06
			R3								GND
			36 kΩ				D2	R4
		C9	C4			BAT46
		100 nF	10 µF
	R5
	N.C.						ALTAIR05T-800			C10
		CDC			VDD			DRAIN
		2.5 V	+			CURRENT			2.2 nF - YCap
			–			CONTROL
		FB/ZCD	COMP		IREF		GND	SOURCE
	R6				C6
	7.5 kΩ				470 nF		C7	R8
			C5						R10
					R7		4.7 nF
			1 nF					1.2	N.C.
											AM00656

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	Table 2.	ALTAIR05T-800 demonstration board: bill of material(1)
	Reference	Part	Description	Note
	R1		22 Ω - 1 W	Axial flame proof
	R2		120 kΩ SMD (1206)
	R3		36 kΩ	1% tolerance
	R4		0 Ω
	R5		Not connected	See Section A.4: Cable
				drop compensation block
	R6		7.5 kΩ	1% tolerance
	R7		10 kΩ
	R8		1.2 Ω	1% tolerance
	R9		1.5 kΩ
	C1, C2		4.7 µF 400 V electrolytic
	C3		1 nF - 500 V XR7
	C4		10 µF - 35 V electrolytic
	C5		1 nF - 25 V
	C6		470 nF - 25 V
	C7		4.7 nF - 25 V
	C8	B41889A4108M	1000 µF - 16 V electrolytic	Epcos
	C9		100 nF - 25 V
	C10	Y1capacitor	2.2 nF - 230 V
	D1	STTH1L06	Ultra fast high voltage diode	STMicroelectronics
	D2	BAT46	Small signal Schottky diode	STMicroelectronics
	D3	STPS3L40UF	Power Schottky diode	STMicroelectronics
	L1	B78108S1474J	470 µH axial inductor	Epcos
	BR	MB6S RC	Input bridge rectifier
	TF	1335.0032 rev.1	Flyback transformer	Magnetica®
	IC	ALTAIR05T-800	Primary switching regulator	STMicroelectronics

1. If not otherwise specified, all resistors are 5%, 1/4 W.

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Figure 3. PCB: top side and through-hole components(1)

1. Layout is not to scale.

Figure 4. PCB: bottom side and SMD components(1)

1. Layout is not to scale.

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Table 3.	ALTAIR05T-800 demonstration board: transformer characteristics
	Name		Value
	Manufacturer		Magnetica
	Part number		1335.0032 rev. 1
	Core		E16/5
	Primary inductance		2.2 mH ± 15%
	Air gap		0.18 mm
	Leakage inductance		66 µH max.
Primary to secondary turn ratio			13.9 ± 5%
	Primary to auxiliary turn ratio		5 ± 5%
	Primary saturation current		0.4 AP max. (BSAT = 0.35 T)
Insulation primary to secondary			4 kV
Figure 5.	Electrical schematic
		N02)
			N3%#
		N!58
			!-
Figure 6.	Side view
			!!GREEN POINT ASOREFERENCE
			MAX

!-

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