Texas Instruments TL3845DR-8, TL3845D-8, TL3845DR, TL3845D, TL3844Y Datasheet

TL284x, TL384x

CURRENT-MODE PWM CONTROLLERS

SLVS038E ± JANUARY 1989 ± REVISED DECEMBER 1999

D Optimized for Off-Line and dc-to-dc			D PACKAGE
	Converters		(TOP VIEW)
D Low Start-Up Current (<1 mA)		COMP					REF
			1		14
D Automatic Feed-Forward Compensation
		NC	2		13		NC
	Pulse-by-Pulse Current Limiting
D		VFB	3		12		VCC
D	Enhanced Load-Response Characteristics	NC	4		11		VC
D Undervoltage Lockout With Hysteresis		ISENSE	5		10		OUTPUT
		NC	6		9		GND
D Double-Pulse Suppression
		RT/CT	7		8		POWER GROUND

DHigh-Current Totem-Pole Output

	D Internally Trimmed Bandgap Reference	NC ± No internal connection
	D 500-kHz Operation	D-8 OR P PACKAGE
	D Error Amplifier With Low Output
			(TOP VIEW)
	Resistance	COMP					REF
	D Designed to Be Interchangeable With			1	8
	UC2842 and UC3842 Series	VFB		2	7		VCC
	description	ISENSE		3	6		OUTPUT
		RT/CT		4	5		GND

The TL284x and TL384x series of control integrated circuits provide the features that are

necessary to implement off-line or dc-to-dc fixed-frequency current-mode control schemes with a minimum number of external components. Some of the internally implemented circuits are an undervoltage lockout (UVLO), featuring a start-up current of less than 1 mA, and a precision reference trimmed for accuracy at the error amplifier input. Other internal circuits include logic to ensure latched operation, a pulse-width modulation (PWM) comparator (which also provides current-limit control), and a totem-pole output stage designed to source or sink high-peak current. The output stage, suitable for driving N-channel MOSFETs, is low when it is in the off state.

Major differences between members of these series are the UVLO thresholds and maximum duty-cycle ranges. Typical UVLO thresholds of 16 V (on) and 10 V (off) on the TLx842 and TLx844 devices make them ideally suited to off-line applications. The corresponding typical thresholds for the TLx843 and TLx845 devices are 8.4 V (on) and 7.6 V (off). The TLx842 and TLx843 devices can operate to duty cycles approaching 100%. A duty-cycle range of 0 to 50% is obtained by the TLx844 and TLx845 by the addition of an internal toggle flip-flop, which blanks the output off every other clock cycle.

The TL284x-series devices are characterized for operation from ±40°C to 85°C. The TL384x-series devices are characterized for operation from 0°C to 70°C.

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters.

Copyright 1999, Texas Instruments Incorporated

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1

TL284x, TL384x

CURRENT-MODE PWM CONTROLLERS

SLVS038E ± JANUARY 1989 ± REVISED DECEMBER 1999

AVAILABLE OPTIONS

		PACKAGED DEVICES			CHIP FORM
	TA
		SMALL OUTLINE	SMALL OUTLINE	PLASTIC DIP
					(Y)
		(D)	(D-8)	(P)
		TL3842D	TL3842D-8	TL3842P	TL3842Y
	0°C to 70°C	TL3843D	TL3843D-8	TL3843P	TL3843Y
		TL3844D	TL3844D-8	TL3844P	TL3844Y
		TL3845D	TL3845D-8	TL3845P	TL3845Y
		TL2842D	TL2842D-8	TL2842P	±
	±40°C to 85°C	TL2843D	TL2843D-8	TL2843P	±
		TL2844D	TL2844D-8	TL2844P	±
		TL2845D	TL2845D-8	TL2845P	±

The D and D-8 packages are available taped and reeled. Add the suffix R to the device type (i.e.,

TL3842DR or TL3842DR-8). Chip forms are tested at 25°C.

functional block diagram

	12
	VCC
	34 V NOM			UVLO
	9			5-V REF	14
		±	+	EN
					REF
	GND
					Internal
					Bias
				Vref	11
				Good
					VC
				Logic

RT/CT	7	OSC			10	OUTPUT
					²
				T	8	POWER
						GROUND
		Error
		Amplifier	2R	S
	3	+			PWM
VFB		±		R
					Latch
			R	1 V
	1
COMP				Current-
				Sense

ISENSE	5	Comparator

² The toggle flip-flop is present only in TL2844, TL2845, TL3844, and TL3845. Pin numbers shown are for the D Package.

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TL284x, TL384x

CURRENT-MODE PWM CONTROLLERS

SLVS038E ± JANUARY 1989 ± REVISED DECEMBER 1999

absolute maximum ratings over operating free-air temperature range (unless otherwise noted)²

Supply voltage (see Note 1) (ICC < 30 mA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . Self limiting
Analog input voltage range, VI (VFB and ISENSE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	±0.3 V to 6.3 V
Output voltage, VO (OUTPUT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . 35 V
Input voltage, VI, (VC, D package only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . 35 V
Supply current, ICC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . 30 mA
Output current, IO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . ±1 A
Error amplifier output sink current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . 10 mA
Package thermal impedance, θJA (see Notes 2 and 3): D package . . . . . . . . . . . . . . . . . . . . . .	. . . . . . 86°C/W
D-8 package . . . . . . . . . . . . . . . . . . . .	. . . . . . 97°C/W
P package . . . . . . . . . . . . . . . . . . . . . .	. . . . . . 85°C/W
Virtual junction temperature range, TJ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. 0°C to 150°C
Output energy (capacitive load) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . 5 µJ
Lead temperature, 1,6 mm (1/16 inch) from case for 10 seconds . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . 260°C
Storage temperature range, Tstg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	±65°C to 150°C

²Stresses beyond those listed under ªabsolute maximum ratingsº may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under ªrecommended operating conditionsº is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.

NOTES: 1. All voltages are with respect to the device GND terminal.

2.Maximum power dissipation is a function of TJ(max), θJA, and TA. The maximum allowable power dissipation at any allowable ambient temperature is PD = (TJ(max) ± TA)/θJA. Operating at the absolute maximum TJ of 150°C can impact reliability.

3.The package thermal impedance is calculated in accordance with JESD 51.

recommended operating conditions

		MIN	NOM	MAX	UNIT
Supply voltage, VCC and VC³				30	V
Input voltage, VI, RT/CT		0		5.5	V
Input voltage, VI, VFB and ISENSE		0		5.5	V
Output voltage, VO, OUTPUT		0		30	V
Output voltage, VO, POWER GROUND³		±0.1		1	V
Supply current, externally limited, ICC				25	mA
Average output current, IO				200	mA
Reference output current, IO(ref)				±20	mA
Oscillator frequency, fosc			100	500	kHz
Operating virtual junction temperature, TJ		0		125	°C
Operating free-air temperature, TA	TL284x	±40		85	°C
	TL384x	0		70

³ These recommended voltages for VC and POWER GROUND apply only to the D package.

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3

TL284x, TL384x

CURRENT-MODE PWM CONTROLLERS

SLVS038E ± JANUARY 1989 ± REVISED DECEMBER 1999

electrical characteristics over recommended operating free-air temperature range, VCC = 15 V (see Note 4), RT = 10 kΩ, CT = 3.3 nF (unless otherwise specified)

reference section

	PARAMETER	TEST CONDITIONS			TL284x			TL384x		UNIT
				MIN	TYP²	MAX	MIN	TYP²	MAX
	Output voltage	IO = 1 mA,	TA = 25°C	4.95	5	5.05	4.9	5	5.1	V
	Line regulation	VCC = 12 V to 25 V			6	20		6	20	mV
	Load regulation	IO = 1 mA to 20 mA			6	25		6	25	mV
	Temperature coefficient				0.2	0.4		0.2	0.4	mV/°C
	of output voltage
	Output voltage	VCC = 12 V to 25 V,	IO = 1 mA to 20 mA	4.9		5.1	4.82		5.18	V
	with worst-case variation
	Output noise voltage	f = 10 Hz to 10 kHz,	TA = 25°C		50			50		µV
	Output-voltage long-term drift	After 1000 h at TA = 25°C			5	25		5	25	mV
	Short-circuit output current			±30	±100	±180	±30	±100	±180	mA
	² All typical values are at T = 25°C.
	A
	NOTE 4: Adjust VCC above the start threshold before setting it to 15 V.
	oscillator section

	PARAMETER	TEST CONDITIONS		TL284x			TL384x		UNIT
			MIN	TYP²	MAX	MIN	TYP²	MAX
	Oscillator frequency (see Note 5)	TA = 25°C	47	52	57	47	52	57	kHz
	Frequency change with supply voltage	VCC = 12 V to 25 V		2	10		2	10	Hz/kHz
	Frequency change with temperature			50			50		Hz/kHz
	Peak-to-peak amplitude at RT/CT			1.7			1.7		V
	² All typical values are at T = 25°C.
	A

NOTES: 4. Adjust VCC above the start threshold before setting it to 15 V.

5.Output frequency equals oscillator frequency for the TLx842 and TLx843. Output frequency is one-half oscillator frequency for the TLx844 and TLx845.

error-amplifier section

	PARAMETER	TEST CONDITIONS			TL284x			TL384x		UNIT
				MIN	TYP²	MAX	MIN	TYP²	MAX
	Feedback input voltage	COMP at 2.5 V		2.45	2.50	2.55	2.42	2.50	2.58	V
	Input bias current				±0.3	±1		±0.3	±2	µA
	Open-loop voltage amplification	VO = 2 V to 4 V		65	90		65	90		dB
	Gain-bandwidth product			0.7	1		0.7	1		MHz
	Supply-voltage rejection ratio	VCC = 12 V to 25 V		60	70		60	70		dB
	Output sink current	VFB at 2.7 V,	COMP at 1.1 V	2	6		2	6		mA
	Output source current	VFB at 2.3 V,	COMP at 5 V	±0.5	±0.8		±0.5	±0.8		mA
	High-level output voltage	VFB at 2.3 V,	RL = 15 kΩ to GND	5	6		5	6		V
	Low-level output voltage	VFB at 2.7 V,	RL = 15 kΩ to GND		0.7	1.1		0.7	1.1	V

² All typical values are at TA = 25°C.

NOTE 4: Adjust VCC above the start threshold before setting it to 15 V.

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