Philips UBA2021T, UBA2021P Datasheet

INTEGRATED CIRCUITS

DATA SHEET

UBA2021

630 V driver IC for CFL and TL lamps

Product specification

2001 Jan 30

Supersedes data of 2000 Jul 24

File under Integrated Circuits, IC11

Philips Semiconductors	Product specification
630 V driver IC for CFL and TL lamps	UBA2021

FEATURES

∙Adjustable preheat and ignition time

∙Adjustable preheat current

∙Adjustable lamp power

∙Lamp temperature stress protection at higher mains voltages

∙Capacitive mode protection

∙Protection against a too-low drive voltage for the power MOSFETs.

QUICK REFERENCE DATA

GENERAL DESCRIPTION

The UBA2021 is a high-voltage IC intended to drive and control Compact Fluorescent Lamps (CFL) or fluorescent TL-lamps. It contains a driver circuit for an external half-bridge, an oscillator and a control circuit for starting up, preheating, ignition, lamp burning and protection.

SYMBOL	PARAMETER	CONDITIONS	MIN.	TYP.	MAX.	UNIT
High voltage supply
VFS	high side supply voltage	IFS < 15 μA; t < 0.5 s	−	−	630	V
Start-up state
VVS(start)	oscillator start voltage		−	11.95	−	V
VVS(stop)	oscillator stop voltage		−	10.15	−	V
IVS(standby)	standby current	VVS = 11 V	−	200	−	μA
Preheat mode
fstart	start frequency		−	108	−	kHz
tph	preheat time	CCP = 100 nF	−	666	−	ms
VRS(ctrl)	control voltage at pin RS		−	−600	−	mV
Frequency sweep to ignition
fB	bottom frequency		−	42.9	−	kHz
tign	ignition time		−	625	−	ms
Normal operation
fB	bottom frequency		−	42.9	−	kHz
tno	non-overlap time		−	1.4	−	μs
Itot	total supply current	fB = 43 kHz	−	1	−	mA
RG1(on), RG2(on)	high and low side on resistance		−	126	−	Ω
RG1(off), RG2(off)	high and low side off resistance		−	75	−	Ω
Feed-forward
fff	feed-forward frequency	IRHV = 0.75 mA	−	63.6	−	kHz
		IRHV = 1.0 mA	−	84.5	−	kHz
Ii(RHV)	operating range of input current at pin RHV		0	−	1000	μA

2001 Jan 30

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Philips Semiconductors				Product specification
630 V driver IC for CFL and TL lamps					UBA2021
ORDERING INFORMATION
TYPE NUMBER			PACKAGE
		NAME	DESCRIPTION		VERSION
UBA2021T		SO14	plastic small outline package; 14 leads; body width 3.9 mm		SOT108-1
UBA2021P		DIP14	plastic dual in-line package; 14 leads (300 mil)		SOT27-1

BLOCK DIAGRAM

		VS	RHV	RREF	CF	CI
		5	13	10	12	14		bootstrap
								charging circuit
							SB
		SUPPLY							1
		4		OSCILLATOR					FS
	n.c.						LEVEL	HIGH SIDE	2
							SHIFTER	DRIVER	G1
									3
		BAND GAP							S1
		REFERENCE
	CP	8		TIMING			NON		6
						OVERLAP		LOW SIDE
								DRIVER	G2
	RS	9	RS	CONTROL					7
		MONITOR					UBA2021		PGND
								11
								SGND	MGS988

Fig.1 Block diagram.

2001 Jan 30

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Philips Semiconductors				Product specification
630 V driver IC for CFL and TL lamps				UBA2021
PINNING
SYMBOL		PIN	DESCRIPTION
FS		1	high side floating supply voltage
G1		2	gate high transistor (T1)
S1		3	source high transistor (T1)
n.c.		4	high-voltage spacer, not to be connected
VS		5	low voltage supply
G2		6	gate low transistor (T2)
PGND		7	power ground
CP		8	timing/averaging capacitor
RS		9	current monitoring input
RREF		10	reference resistor
SGND		11	signal ground
CF		12	oscillator capacitor
RHV		13	start-up resistor/feed-forward resistor
CI		14	integrating capacitor

handbook, halfpage
FS	1			14	CI
G1
	2			13	RHV
S1	3			12	CF
n.c.	4	UBA2021T		11	SGND
VS	5			10	RREF
G2	6			9	RS
PGND	7			8	CP
			MGS989

Fig.2 Pin configuration (SO14).

handbook, halfpage

FS	1			14			CI
G1
	2				13		RHV
S1	3				12		CF
n.c.	4		UBA2021P		11		SGND
VS	5				10		RREF
G2	6				9		RS
PGND	7				8		CP
			MGS990

Fig.3 Pin configuration (DIP14).

2001 Jan 30

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Philips Semiconductors	Product specification
630 V driver IC for CFL and TL lamps	UBA2021

FUNCTIONAL DESCRIPTION

Introduction

The UBA2021 is an integrated circuit for electronically ballasted compact fluorescent lamps and their derivatives operating with mains voltages up to 240 V (RMS). It provides all the necessary functions for preheat, ignition and on-state operation of the lamp. In addition to the control function, the IC provides level shift and drive functions for the two discrete power MOSFETs, T1 and T2 (see Fig.7).

Initial start-up

Initial start-up is achieved by charging capacitor CS9 with the current applied to pin RHV. At start-up, MOSFET T2 conducts and T1 is non-conducting, ensuring Cboot becomes charged. This start-up state is reached for a

supply voltage VVS(reset) (this is the voltage level at pin VS at which the circuit will be reset to the initial state) and

maintained until the low voltage supply (VVS) reaches a value of VVS(start). The circuit is reset in the start-up state.

Oscillation

When the low voltage supply (VVS) has reached the value

of VVS(start) the circuit starts oscillating in the preheat state. The internal oscillator is a current-controlled circuit which

generates a sawtooth waveform. The frequency of the sawtooth is determined by the capacitor CCF and the

current out of pin CF (mainly set by RRREF). The sawtooth frequency is twice the frequency of the signal across the

load. The IC brings MOSFETs T1 and T2 alternately into conduction with a duty factor of approximately 50%. Figure 4 represents the timing of the IC. The circuit block 'non-overlap' generates a non-overlap time tno that ensures conduction periods of exclusively T1 or T2. Time tno is dependent on the reference current IRREF.

handbook, halfpage		MGS991
VCF	start-up
0
internal
clock
0
V(G1-S1)
0
V(G2)	tno	tno
0
		time

Fig.4 Oscillator timing.

Operation in the preheat mode

The circuit starts oscillating at approximately 2.5 × fB (108 kHz). The frequency gradually decreases until a

defined value of current Ishunt is reached (see Fig.5). The slope of the decrease in frequency is determined by

capacitor CCI. The frequency during preheating is approximately 90 kHz. This frequency is well above the resonant frequency of the load, which means that the lamp is off; the load consists of L2, C5 and the electrode resistance only. The preheat time is determined by capacitor CCP. The circuit can be locked in the preheat state by connecting pin CP to ground. During preheating, the circuit monitors the load current by measuring the

voltage drop over external resistor Rshunt at the end of conduction of T2 with decision level VRS(ctrl). The frequency is decreased as long as VRS > VRS(ctrl). The frequency is increased for VRS < VRS(ctrl).

2001 Jan 30

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Philips Semiconductors	Product specification
630 V driver IC for CFL and TL lamps	UBA2021

	handbook, halfpage		MGS992
	fstart
	fB
	preheat state	ignition	burn state
		state
			time

For calculations refer to Chapter “Design equations”.

Fig.5 Operation in the preheat mode.

Ignition state

The RS monitoring function changes from VRS(ctrl) regulation to capacitive mode protection at the end of the

preheat time. Normally this results in a further frequency decrease down to the bottom frequency fB (approximately 43 kHz). The rate of change of frequency in the ignition state is less than that in the preheat mode. During the downward frequency sweep, the circuit sweeps through the resonant frequency of the load. A high voltage then appears across the lamp. This voltage normally ignites the lamp.

Failure to ignite

Excessive current levels may occur if the lamp fails to ignite. The IC does not limit these currents in any manner.

Transition to the burn state

Assuming that the lamp has ignited during the downward frequency sweep, the frequency normally decreases to the bottom frequency. The IC can transit to the burn state in two ways:

1.In the event that the bottom frequency is not reached, transition is made after reaching the ignition time tign.

2.As soon as the bottom frequency is reached.

The bottom frequency is determined by RRREF and CCF.

Feed-forward frequency

Above a defined voltage level the oscillation frequency also depends on the supply voltage of the half-bridge (see Fig.6). The current for the current-controlled oscillator is in the feed-forward range derived from the current through RRHV. The feed-forward frequency is proportional to the average value of the current through RRHV within the

operating range of Ii(RHV), given the lower limit set by fB. For currents beyond the operating range (i.e. between

1.0 and 1.6 mA) the feed-forward frequency is clamped. In order to prevent feed-forward of ripple on Vin, the ripple is filtered out. The capacitor connected to pin CP is used for this purpose. This pin is also used in the preheat state and the ignition state for timing (tph and tign).

handbook, halfpage	MGS993

f (kHz)

feed-forward range

bottom frequency

IRHV (mA)

For calculations refer to Chapter “Design equations”.

Fig.6 Feed-forward frequency.

Capacitive mode protection

When the preheat mode is completed, the IC will protect the power circuit against losing the zero voltage switching condition and getting too close to the capacitive mode of operation. This is detected by monitoring voltage VRS at

pin RS. If the voltage is below VRS(cap) at the time of turn-on of T2, then capacitive mode operation is assumed.

Consequently the frequency increases as long as the capacitive mode is detected. The frequency decreases down to the feed-forward frequency if no capacitive mode is detected. Frequency modulation is achieved via pin CI.

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