NSC LM2588T-ADJ, LM2588T-5.0, LM2588T-12, LM2588SX-ADJ, LM2588SX-5.0 Datasheet

April 1998

LM2588

SIMPLE SWITCHER® 5A Flyback Regulator with Shutdown

General Description

The LM2588 series of regulators are monolithic integrated circuits specifically designed for flyback, step-up (boost), and forward converter applications. The device is available in 4 different output voltage versions: 3.3V, 5.0V, 12V, and adjustable.

Requiring a minimum number of external components, these regulators are cost effective, and simple to use. Included in the datasheet are typical circuits of boost and flyback regulators. Also listed are selector guides for diodes and capacitors and a family of standard inductors and flyback transformers designed to work with these switching regulators.

The power switch is a 5.0A NPN device that can stand-off 65V. Protecting the power switch are current and thermal limiting circuits, and an undervoltage lockout circuit. This IC contains an adjustable frequency oscillator that can be programmed up to 200 kHz. The oscillator can also be synchronized with other devices, so that multiple devices can operate at the same switching frequency.

Other features include soft start mode to reduce in-rush current during start up, and current mode control for improved rejection of input voltage and output load transients and cycle-by-cycle current limiting. The device also has a shutdown pin, so that it can be turned off externally. An output voltage tolerance of ±4%, within specified input voltages and output load conditions, is guaranteed for the power supply system.

Features

nRequires few external components

nFamily of standard inductors and transformers

nNPN output switches 5.0A, can stand off 65V

nWide input voltage range: 4V to 40V

nAdjustable switching frequency: 100 kHz to 200 kHz

nExternal shutdown capability

nDraws less than 60 µA when shut down

nFrequency synchronization

nCurrent-mode operation for improved transient response, line regulation, and current limit

nInternal soft-start function reduces in-rush current during start-up

nOutput transistor protected by current limit, under voltage lockout, and thermal shutdown

nSystem output voltage tolerance of ±4% max over line and load conditions

Typical Applications

nFlyback regulator

nForward converter

nMultiple-output regulator

nSimple boost regulator

Flyback Regulator

DS012420-1

SIMPLE SWITCHER® and Switchers Made Simple ® are registered trademarks of National Semiconductor Corporation.

Shutdown with Regulator Flyback 5A SWITCHER SIMPLE LM2588

© 1999 National Semiconductor Corporation

DS012420

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Ordering Information

Package Type		NSC Package	Order Number
		Drawing
7-Lead TO-220	Bent, Staggered Leads	TA07B	LM2588T-3.3, LM2588T-5.0, LM2588T-12, LM2588T-ADJ
7-Lead TO-263		TS7B	LM2588S-3.3, LM2588S-5.0, LM2588S-12, LM2588S-ADJ
7-Lead TO-263	Tape and Reel	TS7B	LM2588SX-3.3, LM2588SX-5.0, LM2588SX-12,
			LM2588SX-ADJ

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Absolute Maximum Ratings (Note 1)

If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications.

Input Voltage		−0.4V		≤ VIN ≤ 45V
Switch Voltage		−0.4V		≤ VSW ≤ 65V
Switch Current (Note 2)		Internally Limited
Compensation Pin Voltage		−0.4V	≤ VCOMP ≤ 2.4V
Feedback Pin Voltage		−0.4V	≤ VFB ≤ 2 VOUT
ON	/OFF Pin Voltage	−0.4V ≤ VSH ≤ 6V
Sync Pin Voltage		−0.4V ≤ VSYNC ≤ 2V
Power Dissipation (Note 3)		Internally Limited
Storage Temperature Range			−65ÊC to +150ÊC

Lead Temperature
(Soldering, 10 sec.)	260ÊC
Maximum Junction Temperature
(Note 3)	150ÊC
Minimum ESD Rating
(C = 100 pF, R = 1.5 kΩ)	2 kV

Operating Ratings

Supply Voltage	4V ≤ VIN ≤ 40V
Output Switch Voltage	0V ≤ VSW ≤ 60V
Output Switch Current	ISW ≤ 5.0A
Junction Temperature Range	−40ÊC ≤ TJ ≤ +125ÊC

LM2588-3.3

Electrical Characteristics

Specifications with standard type face are for TJ = 25ÊC, and those in bold type face apply over full Operating Temperature Range. Unless otherwise specified, VIN = 5V.

Symbol	Parameters	Conditions	Typical	Min	Max	Units
SYSTEM PARAMETERS Test Circuit of Figure 1 (Note 4)
VOUT	Output Voltage	VIN = 4V to 12V	3.3	3.17/3.14	3.43/3.46	V
		ILOAD = 400 mA to 1.75A
VOUT/	Line Regulation	VIN = 4V to 12V	20		50/100	mV
VIN		ILOAD = 400 mA
VOUT/	Load Regulation	VIN = 12V	20		50/100	mV
ILOAD		ILOAD = 400 mA to 1.75A
η	Efficiency	VIN = 12V, ILOAD = 1A	75			%
UNIQUE DEVICE PARAMETERS (Note 5)
VREF	Output Reference	Measured at Feedback Pin	3.3	3.242/3.234	3.358/3.366	V
	Voltage	VCOMP = 1.0V
VREF	Reference Voltage	VIN = 4V to 40V	2.0			mV
	Line Regulation
GM	Error Amp	ICOMP = −30 µA to +30 µA	1.193	0.678	2.259	mmho
	Transconductance	VCOMP = 1.0V
AVOL	Error Amp	VCOMP = 0.5V to 1.6V	260	151/75		V/V
	Voltage Gain	RCOMP = 1.0 MΩ (Note 6)

LM2588-5.0

Electrical Characteristics

Specifications with standard type face are for TJ = 25ÊC, and those in bold type face apply over full Operating Temperature Range. Unless otherwise specified, VIN = 5V.

Symbol	Parameters	Conditions	Typical	Min	Max	Units
SYSTEM PARAMETERS Test Circuit of Figure 1 (Note 4)
VOUT	Output Voltage	VIN = 4V to 12V	5.0	4.80/4.75	5.20/5.25	V
		ILOAD = 500 mA to 1.45A
VOUT/	Line Regulation	VIN = 4V to 12V	20		50/100	mV
VIN		ILOAD = 500 mA
VOUT/	Load Regulation	VIN = 12V	20		50/100	mV
ILOAD		ILOAD = 500 mA to 1.45A
η	Efficiency	VIN = 12V, ILOAD = 750 mA	80			%
UNIQUE DEVICE PARAMETERS (Note 5)
VREF	Output Reference	Measured at Feedback Pin	5.0	4.913/4.900	5.088/5.100	V
	Voltage	VCOMP = 1.0V

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LM2588-5.0

Electrical Characteristics (Continued)

Specifications with standard type face are for TJ = 25ÊC, and those in bold type face apply over full Operating Temperature Range. Unless otherwise specified, VIN = 5V.

Symbol	Parameters	Conditions	Typical	Min	Max	Units
UNIQUE DEVICE PARAMETERS (Note 5)
VREF	Reference Voltage	VIN = 4V to 40V	3.3			mV
	Line Regulation
GM	Error Amp	ICOMP = −30 µA to +30 µA	0.750	0.447	1.491	mmho
	Transconductance	VCOMP = 1.0V
AVOL	Error Amp	VCOMP = 0.5V to 1.6V	165	99/49		V/V
	Voltage Gain	RCOMP = 1.0 MΩ (Note 6)

LM2588-12

Electrical Characteristics

Specifications with standard type face are for TJ = 25ÊC, and those in bold type face apply over full Operating Temperature Range. Unless otherwise specified, VIN = 5V.

Symbol	Parameters	Conditions	Typical	Min	Max	Units
SYSTEM PARAMETERS Test Circuit of Figure 2 (Note 4)
VOUT	Output Voltage	VIN = 4V to 10V	12.0	11.52/11.40	12.48/12.60	V
		ILOAD = 300 mA to 1.2A
VOUT/	Line Regulation	VIN = 4V to 10V	20		100/200	mV
VIN		ILOAD = 300 mA
VOUT/	Load Regulation	VIN = 10V	20		100/200	mV
ILOAD		ILOAD = 300 mA to 1.2A
η	Efficiency	VIN = 10V, ILOAD = 1A	90			%
UNIQUE DEVICE PARAMETERS (Note 5)
VREF	Output Reference	Measured at Feedback Pin	12.0	11.79/11.76	12.21/12.24	V
	Voltage	VCOMP = 1.0V
VREF	Reference Voltage	VIN = 4V to 40V	7.8			mV
	Line Regulation
GM	Error Amp	ICOMP = −30 µA to +30 µA	0.328	0.186	0.621	mmho
	Transconductance	VCOMP = 1.0V
AVOL	Error Amp	VCOMP = 0.5V to 1.6V	70	41/21		V/V
	Voltage Gain	RCOMP = 1.0 MΩ (Note 6)

LM2588-ADJ

Electrical Characteristics

Specifications with standard type face are for TJ = 25ÊC, and those in bold type face apply over full Operating Temperature Range. Unless otherwise specified, VIN = 5V.

Symbol	Parameters	Conditions	Typical	Min	Max	Units
SYSTEM PARAMETERS Test Circuit of Figure 2 (Note 4)
VOUT	Output Voltage	VIN = 4V to 10V	12.0	11.52/11.40	12.48/12.60	V
		ILOAD = 300 mA to 1.2A
VOUT/	Line Regulation	VIN = 4V to 10V	20		100/200	mV
VIN		ILOAD = 300 mA
VOUT/	Load Regulation	VIN = 10V	20		100/200	mV
ILOAD		ILOAD = 300 mA to 1.2A
η	Efficiency	VIN = 10V, ILOAD = 1A	90			%

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LM2588-ADJ

Electrical Characteristics (Continued)

Specifications with standard type face are for TJ = 25ÊC, and those in bold type face apply over full Operating Temperature Range. Unless otherwise specified, VIN = 5V.

Symbol	Parameters	Conditions	Typical	Min	Max	Units
UNIQUE DEVICE PARAMETERS (Note 5)
VREF	Output Reference	Measured at Feedback Pin	1.230	1.208/1.205	1.252/1.255	V
	Voltage	VCOMP = 1.0V
VREF	Reference Voltage	VIN = 4V to 40V	1.5			mV
	Line Regulation
GM	Error Amp	ICOMP = −30 µA to +30 µA	3.200	1.800	6.000	mmho
	Transconductance	VCOMP = 1.0V
AVOL	Error Amp	VCOMP = 0.5V to 1.6V	670	400/200		V/V
	Voltage Gain	RCOMP = 1.0 MΩ (Note 6)
IB	Error Amp	VCOMP = 1.0V	125		425/600	nA
	Input Bias Current

All Output Voltage Versions Electrical Characteristics (Note 5)

Specifications with standard type face are for TJ = 25ÊC, and those in bold type face apply over full Operating Temperature Range. Unless otherwise specified, VIN = 5V.

Symbol	Parameters	Conditions	Typical	Min	Max	Units
IS	Input Supply Current	Switch Off	11		15.5/16.5	mA
		(Note 8)
		ISWITCH = 3.0A	85		140/165	mA
IS/D	Shutdown Input	VSH = 3V	16		100/300	µA
	Supply Current
VUV	Input Supply	RLOAD = 100Ω	3.30	3.05	3.75	V
	Undervoltage
	Lockout
fO	Oscillator Frequency	Measured at Switch Pin
		RLOAD = 100Ω, VCOMP = 1.0V	100	85/75	115/125	kHz
		Freq. Adj. Pin Open (Pin 1)
		RSET = 22 kΩ	200			kHz
fSC	Short-Circuit	Measured at Switch Pin
	Frequency	RLOAD = 100Ω	25			kHz
		VFEEDBACK = 1.15V
VEAO	Error Amplifier	Upper Limit	2.8	2.6/2.4		V
	Output Swing	(Note 7)
		Lower Limit	0.25		0.40/0.55	V
		(Note 8)
IEAO	Error Amp	(Note 9)
	Output Current		165	110/70	260/320	µA
	(Source or Sink)
ISS	Soft Start Current	VFEEDBACK = 0.92V	11.0	8.0/7.0	17.0/19.0	µA
		VCOMP = 1.0V
DMAX	Maximum Duty	RLOAD = 100Ω	98	93/90		%
	Cycle	(Note 7)
IL	Switch Leakage	Switch Off	15		300/600	µA
	Current	VSWITCH = 60V
VSUS	Switch Sustaining	dV/dT = 1.5V/ns		65		V
	Voltage

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All Output Voltage Versions

Electrical Characteristics (Note 5) (Continued)

Specifications with standard type face are for TJ = 25ÊC, and those in bold type face apply over full Operating Temperature Range. Unless otherwise specified, VIN = 5V.

Symbol			Parameters	Conditions	Typical	Min	Max	Units
VSAT	Switch Saturation			ISWITCH = 5.0A	0.7		1.1/1.4	V
	Voltage
ICL	NPN Switch Current				6.5	5.0	9.5	A
	Limit
VSTH	Synchronization			FSYNC = 200 kHz	0.75	0.625/0.40	0.875/1.00	V
	Threshold Voltage			VCOMP = 1V, VIN = 5V
ISYNC	Synchronization			VIN = 5V	100		200	µA
	Pin Current			VCOMP = 1V, VSYNC = VSTH
VSHTH				VCOMP = 1V	1.6	1.0/0.8	2.2/2.4	V
		ON	/OFF Pin (Pin 1)
	Threshold Voltage			(Note 10)
ISH				VCOMP = 1V	40	15/10	65/75	µA
		ON	/OFF Pin (Pin 1)
	Current			VSH = VSHTH
θJA	Thermal Resistance			T Package, Junction to Ambient	65
				(Note 11)
θJA				T Package, Junction to Ambient	45
				(Note 12)
θJC				T Package, Junction to Case	2
θJA				S Package, Junction to Ambient	56			ÊC/W
				(Note 13)
θJA				S Package, Junction to Ambient	35
				(Note 14)
θJA				S Package, Junction to Ambient	26
				(Note 15)
θJC				S Package, Junction to Case	2

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. These ratings apply when the current is limited to less than 1.2 mA for pins 1, 2, 3, and 6. Operating ratings indicate conditions for which the device is intended to be functional, but device parameter specifications may not be guaranteed under these conditions. For guaranteed specifications and test conditions, see the Electrical Characteristics.

Note 2: Note that switch current and output current are not identical in a step-up regulator. Output current cannot be internally limited when the LM2588 is used as a step-up regulator. To prevent damage to the switch, the output current must be externally limited to 5A. However, output current is internally limited when the LM2588 is used as a flyback regulator (see the Application Hints section for more information).

Note 3: The junction temperature of the device (TJ) is a function of the ambient temperature (TA), the junction-to-ambient thermal resistance (qJA), and the power

dissipation of the device (PD). A thermal shutdown will occur if the temperature exceeds the maximum junction temperature of the device: PD x qJA + TA(MAX) ³ TJ- (MAX). For a safe thermal design, check that the maximum power dissipated by the device is less than: PD £ [TJ(MAX) − T A(MAX)]/qJA. When calculating the maximum allowable power dissipation, derate the maximum junction temperature Ð this ensures a margin of safety in the thermal design.

Note 4: External components such as the diode, inductor, input and output capacitors can affect switching regulator performance. When the LM2588 is used as shown in Figure 1 and Figure 2, system performance will be as specified by the system parameters.

Note 5: All room temperature limits are 100% production tested, and all limits at temperature extremes are guaranteed via correlation using standard Statistical Quality Control (SQC) methods.

Note 6: A 1.0 MW resistor is connected to the compensation pin (which is the error amplifier output) to ensure accuracy in measuring AVOL.

Note 7: To measure this parameter, the feedback voltage is set to a low value, depending on the output version of the device, to force the error amplifier output high and the switch on.

Note 8: To measure this parameter, the feedback voltage is set to a high value, depending on the output version of the device, to force the error amplifier output low and the switch off.

Note 9: To measure the worst-case error amplifier output current, the LM2588 is tested with the feedback voltage set to its low value (specified in (Note 7)) and at its high value (specified in (Note 8)).

Note 10: When testing the minimum value, do not sink current from this pin Ð isolate it with a diode. If current is drawn from this pin, the frequency adjust circui t will begin operation (see Figure 41).

Note 11: Junction to ambient thermal resistance (no external heat sink) for the 7 lead TO-220 package mounted vertically, with 1¤2 inch leads in a socket, or on a PC board with minimum copper area.

Note 12: Junction to ambient thermal resistance (no external heat sink) for the 7 lead TO-220 package mounted vertically, with 1¤2 inch leads soldered to a PC board containing approximately 4 square inches of (1 oz.) copper area surrounding the leads.

Note 13: Junction to ambient thermal resistance for the 7 lead TO-263 mounted horizontally against a PC board area of 0.136 square inches (the same size as the TO-263 package) of 1 oz. (0.0014 in. thick) copper.

Note 14: Junction to ambient thermal resistance for the 7 lead TO-263 mounted horizontally against a PC board area of 0.4896 square inches (3.6 times the area of the TO-263 package) of 1 oz. (0.0014 in. thick) copper.

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All Output Voltage Versions

Electrical Characteristics (Note 5) (Continued)

Note 15: Junction to ambient thermal resistance for the 7 lead TO-263 mounted horizontally against a PC board copper area of 1.0064 square inches (7.4 times the area of the TO-263 package) of 1 oz. (0.0014 in. thick) copper. Additional copper area will reduce thermal resistance further. See the thermal model in Switchers Made Simple® software.

Typical Performance Characteristics

Supply Current	Reference Voltage	Reference Voltage
vs Temperature	vs Temperature	vs Supply Voltage

DS012420-2 DS012420-3 DS012420-4

Supply Current	Current Limit	Feedback Pin Bias
vs Switch Current	vs Temperature	Current vs Temperature

DS012420-5	DS012420-6	DS012420-7

Switch Saturation	Switch Transconductance	Oscillator Frequency
Voltage vs Temperature	vs Temperature	vs Temperature

DS012420-8	DS012420-9	DS012420-10

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Typical Performance Characteristics (Continued)

Error Amp Transconductance	Error Amp Voltage	Short Circuit Frequency
vs Temperature	Gain vs Temperature	vs Temperature

	DS012420-11		DS012420-12	DS012420-13
Shutdown Supply Current
		ON /OFF Pin Current		Oscillator Frequency
vs Temperature		vs Voltage		vs Resistance

DS012420-14	DS012420-15	DS012420-16
Connection Diagrams
Bent, Staggered Leads		Bent, Staggered Leads
7-Lead TO-220 (T)
		7-Lead TO-220 (T)
Top View
		Side View
		DS012420-18
	DS012420-17

Order Number LM2588T-3.3, LM2588T-5.0,

LM2588T-12 or LM2588T-ADJ

See NS Package Number TA07B

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Connection Diagrams (Continued)

7-Lead TO-263 (S)	7-Lead TO-263 (S)
Top View	Side View

DS012420-20

DS012420-19

Order Number LM2588S-3.3, LM2588S-5.0,

LM2588S-12 or LM2588S-ADJ

Tape and Reel Order Number LM2588SX-3.3,

LM2588SX-5.0, LM2588SX-12 or LM2588SX-ADJ

See NS Package Number TS7B

Test Circuits

DS012420-21

CIN1 Ð 100 µF, 25V Aluminum Electrolytic

CIN2 Ð 0.1 µF Ceramic

T Ð 22 µH, 1:1 Schott #67141450

D Ð 1N5820

COUT Ð 680 µF, 16V Aluminum Electrolytic

CC Ð 0.47 µF Ceramic

RC Ð 2k

FIGURE 1. LM2588-3.3 and LM2588-5.0

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