Sipex Corporation SPX1085AR, SPX1085AR-1.5, SPX1085AR-2.5, SPX1085AR-3.3, SPX1085AR-5.0 Datasheet

SPX1085

	3A Low Dropout Voltage Regulator
	Adjustable & Fixed Output,
	Fast Response
FEATURES	APPLICATIONS
• Adjustable Output Down To 1.2V	• Powering VGA & Sound Card
• Fixed Output Voltages 1.5, 2.5, 3.3, 5.0V	• Power PC Supplies
• Output Current Of 3A	• SMPS Post-Regulator
• Low Dropout Voltage 1.1V Typ.	• High Efficiency “Green” Computer Systems
• Extremely Tight Load And Line Regulation	• High Efficiency Linear Power Supplies
• Current & Thermal Limiting	• Portable Instrumentation
• Standard 3-Terminal Low Cost TO-220, TO-263 & TO-252	• Constant Current Regulators
• Similar To Industry Standard LT1085/LT1585	• Adjustable Power Supplies
	• Battery charger

PRODUCT DESCRIPTION

The SPX1085 are low power 3A adjustable and fixed voltage regulators that are very easy to use. It requires only 2 external resistors to set the output voltage for adjustable version. The SPX1085 is designed for low voltage applications that offer lower dropout voltage and faster transient response. This device is an excellent choice for use in powering low voltage microprocessor that require a lower dropout, faster transient response to regulate from +2.5V to 3.8V supplies and as a post regulator for switching supplies applications. The SPX1085 features low dropout of a maximum of 1.5 volts.

The SPX1085 offers full protection against over-current faults, reversed input polarity, reversed load insertion, and positive and negative transient voltage. On-Chip trimming adjusts the reference voltage to 1%. The IQ of this device flows into load which increases efficiency.

The SPX1085 are offered in a 3-pin TO-220, TO-263 & TO-252 packages compatible with other 3 terminal regulators. For a 8A low dropout regulator refer to the SPX1085 data sheet.

PIN CONNECTIONS

TO-263-3 (T)			TO-220-3 (U)			TO-252 (R)
SPX1085						SPX1085
1	2	3	SPX1085			1	2	3
			1	2	3
						ADJ/GND VOUT VIN
ADJ/GND	VOUT	VIN				Front View

Top View

ADJ/GND VOUT VIN

Front View

Rev. 10/30/00

SPX1085

ABSOLUTE MAXIMUM RATINGS

Lead Temp. (Soldering, 10 Seconds) ..............................	300°C	Input Voltage........................................................	30V
Storage Temperature Range ............................	-65° to +150°C	Input to Output Voltage Differential Max ............	30V
Operating Junction Temperature Range ......................
SPX1085 Control Section..........................	-45°C +125°C
SPX1085 Power Transistor.........................	-45°C +150°C

ELECTRICAL CHARACTERISTICS (NOTE 1) at IOUT = 10mA, TA=25°C, unless otherwise specified.

PARAMETER		CONDITIONS			Typ	SPX1085A		SPX1085		Units
						Min	Max	Min	Max
1.5V Version
Output Voltage	(Note 2)	SPX1085-1.5V, 0 ≤IOUT≤3A, 2.75V≤VIN ≤29V			1.5	1.485	1.515	1.470	1.530	V
					1.5	1.470	1.530	1.455	1.545
2.5V Version
Output Voltage (Note 2)		SPX1085-2.5V,0 ≤IOUT≤3A, 3.5V≤VIN ≤29V			2.5	2.475	2.525	2.450	2.550	V
					2.5	2.450	2.550	2.425	2.575
3.3V Version
Output Voltage	(Note 2)	SPX1085-3.3V, 0 ≤IOUT≤3A, 4.75V≤VIN ≤29V			3.3	3.270	3.330	3.230	3.370	V
					3.3	3.240	3.360	3.201	3.399
5.0V Version
Output Voltage	(Note 2)	SPX1085-5.0V, 0 ≤IOUT≤3A, 5.5V≤VIN ≤29V			5.0	4.95	5.05	4.900	5.100	V
					5.0	4.90	5.10	4.850	5.150
Adjustable Version
Reference Voltage (VREF)		VIN≤ 7V, P≤ PMAX
		1.5V≤ (VIN -VOUT)≤(VIN-VOUT)MAX,			1.250	1.238	1.263	1.225	1.270	V
		10mA≤IOUT≤3A
All Voltage Options
Min. Load Current (Note 3)		1.5V≤ (VIN -VOUT)≤ (VIN-VOUT)MAX			5		10		10	mA
Line Regulation (∆VREF(VIN))		2.75V≤VIN ≤29V, IOUT=10mA, TJ=25°C (Note 3)			0.005		0.2		0.2	%
		VIN ≤29V, IOUT=0mA, TJ=25°C (Note 2)			0.005		0.2		0.2	%
Load Regulation(∆VREF(IOUT))		10mA≤IOUT ≤3A, (VIN-VOUT)=3V, TJ=25°C (Note			0.05		0.3		0.3	%
		3)
		0≤IOUT ≤3A, VIN=7V, TJ=25°C (Note 2)			0.05		0.3		0.3	%
Dropout Voltage		∆VREF=1%	IOUT =3A (Note 3)		1.1		1.5		1.5	V
			IOUT≤ 3A (Note 2)
Current Limit		VIN=7V								A
IOUT(MAX)		1.4V≤ (VIN- VOUT) (Note3)			4.0	3.2		3.2
Long Term Stability		TA=125°C, 1000 Hrs.			0.3		1		1	%
					(Note 2)
Thermal Regulation		TA=25°C, 20 ms pulse			0.01		0.020		0.020	%/W
(∆VOUT(Pwr))
Temperature Stability					0.25					%
(∆VOUT(T))
Output Noise, RMS		10Hz to 10kHz	TA=25°C		0.003					% VO
Thermal Resistance		TO-220		Junction to Tab	3.0		3.0		3.0	°C/W
				Junction to Ambient	60		60		60	°C/W
		DD Package		Junction to Tab	3.0		3.0		3.0
				Junction to Ambient	60		60		60

The Bold specifications apply to the full operating temperature range.

Note 1: Changes in output voltage due to heating effects are covered under the specification for thermal regulation.

Note 2: Fixed Version Only

Note 3: Adjustable Version Only

Rev. 10/30/00

SPX1085

APPLICATION HINTS

The SPX1085 incorporates protection against over-current faults, reversed load insertion, over temperature operation, and positive and negative transient voltage. However, the use of an output capacitor is required in order to insure the stability and the performances.

Stability

The output capacitor is part of the regulator’s frequency compensation system. Either a 220µF aluminum electrolytic capacitor or a 47µF solid tantalum capacitor between the output terminal and ground guarantees stable operation for all operating conditions.

However, in order to minimize overshoot and undershoot, and therefore optimize the design, please refer to the section ‘Ripple Rejection’.

Ripple Rejection

Ripple rejection can be improved by adding a capacitor between the ADJ pin and ground. When ADJ pin bypassing is used, the value of the output capacitor required increases to its maximum (220µF for an aluminum electrolytic capacitor, or 47µF for a solid tantalum capacitor). If the ADJ pin is not bypass, the value of the output capacitor can be lowered to 100µF for an electrolytic aluminum capacitor or 15µF for a solid tantalum capacitor.

However the value of the ADJ-bypass capacitor should be chosen with respect to the following equation:

C = 1 / ( 6.28 * FR * R1 )

Where C	= value of the capacitor in Farads (select an
equal or larger standard value),
FR	= ripple frequency in Hz,
R1	= value of resistor R1 in Ohms.

If an ADJ-bypass capacitor is use, the amplitude of the output ripple will be independent of the output voltage. If an ADJbypass capacitor is not used, the output ripple will be proportional to the ratio of the output voltage to the reference voltage:

M = VOUT / VREF

Where M = multiplier for the ripple seen when the ADJ pin is optimally bypassed.

VREF = Reference Voltage

Reducing parasitic resistance and inductance

One solution to minimize parasitic resistance and inductance is to connect in parallel capacitors. This arrangement will improve the transient response of the power supply if your system requires rapidly changing current load condition.

Thermal Consideration

Although the SPX1085 offers some limiting circuitry for overload conditions, it is necessary not to exceed the maximum junction temperature, and therefore to be careful about thermal resistance. The heat flow will follow the lowest resistance path, which is the Junction-to-case thermal resistance. In order to insure the best thermal flow of the component, a proper mounting is required. Note that the case of the device is electrically connected to the output. In case the case has to be electrically isolated, a thermally conductive spacer can be used. However do not forget to consider its contribution to thermal resistance.

Assuming:

VIN = 10V, VOUT = 5V, IOUT = 1.5A, TA = 50°C

θ Heatsink = 6°C/W, θ Case-Heatsink = 0.5°C/W, θ JC = 3°C/W

Power dissipation under this condition

PD = (VIN – VOUT) * IOUT = 7.5W

Junction Temperature

TJ = TA + PD * (θCase – HS + θ HS + θ JC)

For the Control Sections

TJ = 50 + 7.5*(0.5 +6=3) = 121.25°C 121.25°C < TJ(max) for the control section.

In both case reliable operation is insured by adequate junction temperature.

Rev. 10/30/00