ST ALTAIR04-900 User Manual

ALTAIR04-900

Off-line all-primary-sensing switching regulator

Features

■Primary side constant voltage operations with no optocoupler

■Adjustable and main-independent maximum output current for safe operations during overload/short circuit conditions

■900 V avalanche rugged internal power section

■Quasi-resonant valley switching operation

■Low standby consumption

■Overcurrent protection against transformer saturation and secondary diode short circuit

■SO16 package

SO16N

Applications

■SMPS for energy metering

■Auxiliary power supplies for 3-phases input industrial systems

■AC-DC adapters

Description

ALTAIR04-900 is a high-voltage all-primary- sensing switcher intended for operating directly from the rectified mains with minimum external parts. It combines a high-performance lowvoltage PWM controller chip and a 900 V avalanche-rugged power section in the same package.

Figure 1. Block diagram

									+V out
							+Vi n
	Vcc								Istart-up
				Internal supply bus		SUPPLY			DRAIN
	P ROT ECTION &
					Vref
	FEEDFORWARD					& UV LO
		LOGIC
							UVLO
		Prot	IFF	BLA NKING
				TIME
			3.3 V			START ER			Intern.
									supply
					TURN -ON		S		bus
					LOGIC
Rzcd	ZCD/F B			Vc
		DEMAG					Q
				-
		LOGIC
			R
				+		LEB	R
			S					S	UVLO
	Rfb
			Q					Q
				Iref		1 V
			R				-	R
				+
		-				I FF
	S /H						+
				-
								Prot
		+
	2.5 V					R FF
		COMP	IREF		GND				S OURCE
			Rcomp	Cref
									Rsense
			Ccom p
January 2011				Doc ID 18211 Rev 2					1/29
									www.st.com

Contents	ALTAIR04-900

Contents

1	Device description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		. 3
2	Pin connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		4
3	Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		6
	3.1	Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	6
	3.2	Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	6
4	Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		7
5	Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		11
	5.1	Power section and gate driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	12
	5.2	High voltage startup generator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	12
	5.3	Zero current detection and triggering block . . . . . . . . . . . . . . . . . . . . . . .	13
	5.4	Constant voltage operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	15
	5.5	Constant current operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	16
	5.6	Voltage feedforward block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	17
	5.7	Burst-mode operation at no load or very light load . . . . . . . . . . . . . . . . . .	18
	5.8	Soft-start and starter block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	19
	5.9	Hiccup mode OCP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	20
	5.10	Layout recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	21
6	Typical application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		22
	6.1	Test board: evaluation data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	23
	6.2	Test board: main waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	24
7	Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		25
8	Order codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		27
9	Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		28

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ALTAIR04-900	Device description

1 Device description

The device combines two silicon in the same package: a low voltage PWM controller and a 900 V avalanche rugged power section.

The controller is a current-mode specifically designed for off-line quasi-resonant flyback converters.

The device is capable of providing constant output voltage using all primary sensing feedback. This eliminates the need for the optocoupler, the secondary voltage reference, as well as the current sensor, still maintaining quite accurate regulation. Also, it is possible to set the maximum deliverable output current, thus increasing the end-product's safety and reliability during fault events.

Quasi-resonant operation is guaranteed by means of a transformer demagnetization sensing input that turns on the power section. The same input serves also the output voltage monitor, to perform CV regulation, and the input voltage monitor, to achieve mainsindependent maximum deliverable output current (line voltage feedforward).

The maximum switching frequency is top-limited below 166 kHz, so that at medium-light load a special function automatically lowers the operating frequency still maintaining the valley switching operation. At very light load, the device enters a controlled burst-mode operation that, along with the built-in high-voltage start-up circuit and the low operating current, helps minimize the standby power.

Although an auxiliary winding is required in the transformer to correctly perform CV/CC regulation, the chip is able to power itself directly from the rectified mains. This is useful especially during CC regulation, where the flyback voltage generated by the winding drops below UVLO threshold.

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.

In addition to these functions that optimize power handling under different operating conditions, the device offers protection features that considerably increase end-product's safety and reliability: auxiliary winding disconnection - or brownout - detection and shorted secondary rectifier - or transformer's saturation - detection.

All of them are auto restart mode.

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Pin connection	ALTAIR04-900

2 Pin connection

Figure 2. Pin connection (top view)

SOURCE	1	16	DRAIN
SOURCE	2	15	DRAIN
Vcc	3	14	DRAIN
GND	4	13	DRAIN
IREF	5	12	N.C.
ZCD/FB	6	11	N.A.
COMP	7	10	N.A.
N.A.	8	9	N.A.

	Note:	The copper area for heat dissipation has to be designed under the drain pins
	Table 1.	Pin functions
	N.	Name	Function
			Power section source and input to the PWM comparator. The current flowing in the MOSFET
			is sensed through a resistor connected between the pin and GND. The resulting voltage is
	1, 2	SOURCE	compared with an internal reference (0.75V max.) to determine MOSFET’s turn-off. The pin
			is equipped with 250 ns blanking time after the gate-drive output goes high for improved
			noise immunity. If a second comparison level located at 1V is exceeded the IC is stopped and
			restarted after Vcc has dropped below 5V.
			Supply voltage of the device. An electrolytic capacitor, connected between this pin and
			ground, is initially charged by the internal high-voltage start-up generator; when the device is
	3	Vcc	running the same generator keeps it charged in case the voltage supplied by the auxiliary
			winding is not sufficient. This feature is disabled in case a protection is tripped. Sometimes a
			small bypass capacitor (0.1 µF typ.) to GND might be useful to get a clean bias voltage for
			the signal part of the IC.
			Ground. Current return for both the signal part of the IC and the gate drive. All of the ground
	4	GND	connections of the bias components should be tied to a trace going to this pin and kept
			separate from any pulsed current return.
			CC regulation loop reference voltage. An external capacitor has to be connected between
	5	IREF	this pin and GND. An internal circuit develops a voltage on this capacitor that is used as the
			reference for the MOSFET’s peak drain current during CC regulation. The voltage is
			automatically adjusted to keep the average output current constant.

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	ALTAIR04-900		Pin connection
	Table 1.	Pin functions (continued)
	N.	Name	Function
			Transformer’s demagnetization sensing for quasi-resonant operation. Input/output voltage
			monitor. A negative-going edge triggers MOSFET’s turn-on. The current sourced by the pin
			during ON-time is monitored to get an image of the input voltage to the converter, in order to
			compensate the internal delay of the current sensing circuit and achieve a CC regulation
			independent of the mains voltage. If this current does not exceed 50µA, either a floating pin
	6	ZCD/FB	or an abnormally low input voltage is assumed, the device is stopped and restarted after Vcc
			has dropped below 5V. Still, the pin voltage is sampled-and-held right at the end of
			transformer’s demagnetization to get an accurate image of the output voltage to be fed to the
			inverting input of the internal, transconductance-type, error amplifier, whose non-inverting
			input is referenced to 2.5V. Please note that the maximum IZCD/FB sunk/sourced current has
			to not exceed ±2 mA (AMR) in all the Vin range conditions. No capacitor is allowed between
			the pin and the auxiliary transformer.
			Output of the internal transconductance error amplifier. The compensation network is placed
	7	COMP	between this pin and GND to achieve stability and good dynamic performance of the voltage
			control loop.
	8-11	N.A	Not available. These pins must be left not connected
	12	N.C	Not internally connected. Provision for clearance on the PCB to meet safety requirements.
			Drain connection of the internal power section. The internal high-voltage start-up generator
	13 to 16	DRAIN	sinks current from this pin as well. Pins connected to the internal metal frame to facilitate
			heat dissipation.

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Maximum ratings	ALTAIR04-900

3 Maximum ratings

3.1Absolute maximum ratings

	Table 2.	Absolute maximum ratings
	Symbol	Pin	Parameter	Value	Unit
	VDS	1,2, 13-16	Drain-to-source (ground) voltage	-1 to 900	V
	ID	1,2, 13-16	Drain current	0.7	A
	Eav	1,2, 13-16	Single pulse avalanche energy	25	mJ
			(Tj = 25°C, ID = 0.7A)
	Vcc	3	Supply voltage (Icc < 25mA)	Self limiting	V
	IZCD/FB	6	Zero current detector current	±2	mA
	Vcomp	8	Analog input	-0.3 to 3.6	V
	Ptot		Power dissipation @TA = 50°C	0.9	W
	Tj		Junction temperature range	-25 to 150	°C
	Tstg		Storage temperature	-55 to 150	°C

3.2Thermal data

	Table 3.	Thermal data
	Symbol	Parameter	Max. value	Unit
	Rth j-pin	Thermal resistance, junction-to-pin	10	°C/W
	Rth j-amb	Thermal resistance, junction-to-ambient	110

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ALTAIR04-900	Electrical characteristics

4 Electrical characteristics

(TJ = -25 to 125 °C, Vcc = 14 V; unless otherwise specified)

Table 4.	Electrical characteristics
Symbol	Parameter	Test condition	Min.		Typ.	Max.		Unit
Power section
V(BR)DSS	Drain-source breakdown	ID< 100 µA; Tj = 25 °C	900					V
IDSS	Off state drain current	VDS = 850 V; Tj = 125 °C					80	µA
		(See Figure 4 and note)
RDS(on)	Drain-source ON-state resistance	Id=250 mA; Tj = 25 °C			16		19	W
		Id=250 mA; Tj = 125 °C					38
Coss	Effective (energy-related) output capacitance	(See Figure 3)
High-voltage start-up generator
VStart	Min. Drain start voltage	Icharge < 100 µA	40		50		60	V
		VDRAIN> VStart; Vcc < VccOn	4		5.5		7
Icharge	Vcc startup charge current	Tj = 25 °C						mA
		VDRAIN> VStart; Vcc < VccOn		+/-10%
VCCrestart	Vcc restart voltage (Vcc falling)	(1)	9.5		10.5		11.5	V
		After protection tripping			5
Supply voltage
Vcc	Operating range	After turn-on	11.5				23	V
VccOn	Turn-on threshold	(1)	12		13		14	V
VccOff	Turn-off threshold	(1)	9		10		11	V
VZ	Zener voltage	Icc = 20 mA	23		25		27	V
Supply current
Iccstart-up	Start-up current	(See Figure 5)			200		300	µA
Iq	Quiescent current	(See Figure 6)			1		1.4	mA
Icc	Operating supply current @ 50 kHz	(See Figure 7)			1.4		1.7	mA
Iq(fault)	Fault quiescent current	During hiccup and brownout			250		350	µA
		(See Figure 8)
Start-up timer
TSTART	Start timer period		100		125		175	µs
TRESTART	Restart timer period during burst mode		400		500		700	µs
Zero current detector
IZCDb	Input bias current	VZCD = 0.1 to 3 V			0.1		1	µA
VZCDH	Upper clamp voltage	IZCD = 1 mA	3.0		3.3		3.6	V

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Electrical characteristics					ALTAIR04-900
Table 4.	Electrical characteristics	(continued)
Symbol	Parameter		Test condition	Min.	Typ.	Max.	Unit
VZCDL	Lower clamp voltage		IZCD = - 1 mA	-90	-60	-30	mV
VZCDA	Arming voltage		positive-going edge	100	110	120	mV
VZCDT	Triggering voltage		negative-going edge	50	60	70	mV
IZCDON	Min. source current during MOSFET ON-time			-25	-50	-75	µA
TBLANK	Trigger blanking time after MOSFET’s turn-off		VCOMP ≥ 1.3V		6		µs
			VCOMP = 0.9V		30
Line feedforward
RFF	Equivalent feedforward resistor		IZCD = 1mA		45		Ω
Transconductance error amplifier
			Tj = 25°C (1)	2.46	2.5	2.54
VREF	Voltage reference						V
			Tj = -25 to 125°C and	2.42		2.58
			Vcc=12V to 23V (1)
gm	Transconductance		ICOMP = ±10 µA	1.3	2.2	3.2	mS
			VCOMP = 1.65 V
Gv	Voltage gain		Open loop		73		dB
GB	Gain-bandwidth product				500		KHz
ICOMP	Source current		VZCD = 2.3V, VCOMP = 1.65V	70	100		µA
	Sink current		VZCD = 2.7V, VCOMP = 1.65V	400	750		µA
VCOMPH	Upper COMP voltage		VZCD = 2.3 V		2.7		V
VCOMPL	Lower COMP voltage		VZCD = 2.7 V		0.7		V
VCOMPBM	Burst-mode threshold				1		V
Hys	Burst-mode hysteresis				65		mV
Current reference
VIREFx	Maximum value		(1)	1.5	1.6	1.7	V
			VCOMP = VCOMPL
GI	Current loop gain		VCOMP = VCOMPH	0.5	0.6	0.7
VCREF	Current reference voltage			0.38	0.4	0.42	V
Current sense
tLEB	Leading-edge blanking			200	250	300	ns
td(H-L)	Delay-to-output				300		ns
VCSx	Max. clamp value		dVcs/dt = 200 mV/µs (1)	0.7	0.75	0.8	V
VCSdis	Hiccup-mode OCP level		(1)	0.92	1	1.08	V

1. Parameters tracking each other

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ALTAIR04-900	Electrical characteristics
Figure 3.	COSS Output capacitance variation

COSS (pF)
500
400
300
200
100
0
0	25	50	75	100	125	150

VDS (V)

Figure 4. Off state drain and source current test circuit

I q(f ault ) A

1 5V

A

I dss

		VD D	D R AI N
2. 5V	+		C U R R EN T	850 V
	-		C ON TR OL
FB/ ZC D
	C OMP	I R EF	GN D S OU R C E

Note: The measured IDSS is the sum between the current across the start-up resistor and the effective MOSFET’s off state drain current

Figure 5. Start-up current test circuit

Ic cstart-up

1 1.8 V

A

V D D

D R AIN

2. 5V

+

C UR R EN T

-

C ON TR OL

FB/ ZC D

C OMP

IR EF

GN D SOUR C E

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