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SPX2870
6.5A Low Dropout Voltage Regulator Adjustable & Fixed Output, Fast Response
FEATURES
* Adjustable Output Down To 1.2V * Fixed Output Voltages 2.5, 3.3 & 5.0V * Output Current of 6.5A * Low Dropout Voltage 1.1V Typ. * Extremely Tight Load And Line Regulation * Current & Thermal Limiting * Standard 3-Terminal Low Cost TO-220 & TO-263
APPLICATIONS
* Powering VGA & Sound Card * Power PC Supplies * SMPS Post-Regulator * High Efficiency "Green" Computer Systems * High Efficiency Linear Power Supplies * Portable Instrumentation * Constant Current Regulators * Adjustable Power Supplies * Battery charger
PRODUCT DESCRIPTION
The SPX2870 are low power 6.5A 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 SPX2870 are designed for low voltage applications that offers 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 SPX2870 features low dropout of a maximum 1.5 volts. The SPX2870 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 the load, which increases efficiency. The SPX2870 are offered in a 3-pin TO-220 and TO-263 packages compatible with other 3 terminal regulators. For a 8A low dropout regulator refer to the SPX2880 data sheet.
PIN CONNECTIONS
TO-263-3 (T)
TO-220-3 (U)
SPX2870
1 2 3
SPX2870
1 2 3
ADJ/GND VOUT VIN
Top View
ADJ/GND VOUT VIN
Front View
Rev. 10/30/00
SPX2870
ABSOLUTE MAXIMUM RATINGS
Lead Temp. (Soldering, 10 Seconds) .............................. 300C Storage Temperature Range ............................ -65 to +150C Operating Junction Temperature Range SPX2870 Control Section.......................... -45C +125C SPX2870 Power Transistor.........................-45C +150C Input Voltage........................................................ 10V Input to Output Voltage Differential .................... 10V
ELECTRICAL CHARACTERISTICS (NOTE 1) at IOUT = 10mA, TA=25C, unless otherwise specified.
PARAMETER
2.5V Version Output Voltage (Note 2) 3.3V Version Output Voltage (Note 2) 5.0V Version Output Voltage (Note 2) All Voltage Options Reference Voltage (VREF) Min. Load Current (Note 3) Line Regulation (VREF(VIN)) VIN 7V, P PMAX 1.5V (VIN -VOUT)5.75V, 10mAIOUT5A 1.5V (VIN -VOUT)5.75V 2.75VVIN 7V, IOUT=10mA, TJ=25C (Note 3) VIN 7V, IOUT=0mA, TJ=25C (Note 2) 10mAIOUT 5A, (Vin-VOUT)=3V, TJ=25C (Note 3) 0IOUT 5A, VIN=7V, TJ=25C (Note 2) Dropout Voltage Current Limit IOUT(MAX) Long Term Stability Thermal Regulation (VOUT(PWR)) Temperature Stability (VOUT(T)) Output Noise, RMS Thermal Resistance 10Hz to 10kHz TO-220 Ta=25C Junction to Tab Junction to Ambient Junction to Tab Junction to Ambient VREF=1% VIN=7V 1.4V (VIN - VOUT) (Note3) TA=125C, 1000 Hrs. TA=25C, 20 ms pulse 0.3 (Note 2) 0.01 0.25 0.003 3.0 60 3.0 60 3.0 60 3.0 60 3.0 60 3.0 60 1 0.020 1 0.020 % %/W % % VO C/W IOUT = 6.5A (Note 3) IOUT < 6.5A (Note 2) 6 6.9 1.250 5 0.005 0.005 0.05 0.05 1.225 1.270 10 0.2 0.2 0.3 0.3 1.5 6.9 1.225 1.270 10 0.2 0.2 0.3 0.3 1.5 V A % V V % SPX2870-5.0V, 0 IOUT 6.5A, 6.5VVIN7V 5 4.950 4.900 5.050 5.100 4.9 4.65 5.1 5.15 V SPX2870-3.3V, 0 < IOUT < 6.5A, 4.8VCONDITIONS
Typ
SPX2870A Min Max
SPX2870 Min Max
UNITS
Load Regulation(VREF(IOUT))
DD Package
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
SPX2870
APPLICATION HINTS
The SPX2870 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 220F aluminum electrolytic capacitor or a 47F 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 (220F for an aluminum electrolytic capacitor, or 47F for a solid tantalum capacitor). If the ADJ pin is not bypass, the value of the output capacitor can be lowered to 100F for an electrolytic aluminum capacitor or 15F 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 SPX2870 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 = 50C/W, Heat Case = 6C/W, Heat Case = 0.5C/W, JC = 3C/W Power dissipation under this condition PD = (VIN - VOUT) * IOUT = 7.5W Junction Temperature TJ = TA + PD * (Case - HS + HS + JC ) For the Control Sections TJ = 50 + 7.5W*(0.5 +6=3) = 121.25C 121.25C < TJ(max) for the Control & Power Sections. In both case reliable operation is insured by adequate junction temperature.
Rev. 10/30/00
SPX2870
Basic Adjustable Regulator
VIN
SPX2870
VREF I
ADJ
VOUT R1
50A
* VOUT = VREF * (1 + R2 ) + I ADJ R2 R1
Fig.2 Basic Adjustable Regulator
R2
Output Voltage Consider Figure 2. The resistance R1 generates a constant current flow, normally the specified load current of 10mA. This current will go through the resistance R2 to set the overall output voltage. The current IADJ is very small and constant. Therefore its contribution to the overall output voltage is very small and can generally be ignored Load Regulation Parasitic line resistance can degrade load regulation. In order not to affect the behavior of the regulator, it is best to connect directly the R1 resistance from the resistor divider to the case, and not to the load. For the same reason, it is best to connect the resistor R2 to the Negative side of the load.
VIN
R P Parasitic Line Resistance
SPX2870
Connect R 1 to Case of Regulator
R1
RL R2
Connect R 2 to Load
Fig.3 Basic Adjustable Regulator
Rev. 10/30/00
SPX2870
TYPICAL APPLICATIONS
VIN C1
IN
SPX2870
ADJ
OUT R1
VIN C1
IN
SPX2870
ADJ
OUT C2 R1
VOUT
LOAD
VOUT = VREF (1 + R2 ) + IADJ R2 R1
R2
Fig. 4 6.5A Current output Regulator
Fig. 5 Typical Adjustable Regulator
(Note A) VIN
IN
5V
+ 10F
SPX2870
ADJ
OUT
VOUT
R1 121 1% 150F
VIN (Note A) +
IN
SPX2870
ADJ
OUT
5V 121 1% + 100F
10F 1k 2N3904 1k 365 1%
*C 1 improves ripple rejection. Xc should be ~ R 1 at ripple frequency.
R2 365 1%
TTL Input
+
C1 10F*
Note A: V IN(MIN) = (Intended V OUT) + (VDROPOUT (MAX)) Note A: VIN(MIN)= (Intended V ) + (VDROPOUT (MAX)) OUT
Fig. 6
Improving Ripple Rejection
Fig.7 5V Regulator with Shutdown
Rev. 10/30/00
SPX2870
TYPICAL CHARACTERISTICS
Rev. 10/30/00
SPX2870
ORDERING INFORMATION Ordering No.
SPX2870U SPX2870U-2.5 SPX2870U-3.3 SPX2870U-5.0 SPX2870AU SPX2870AU-2.5 SPX2870AU-3.3 SPX2870AU-5.0 SPX2870T SPX2870T-2.5 SPX2870T-3.3 SPX2870T-5.0 SPX2870AT SPX2870AT-2.5 SPX2870AT-3.3 SPX2870AT-5.0
Precision
2% 2% 2% 2% 1% 1% 1% 1% 2% 2% 2% 2% 1% 1% 1% 1%
Output Voltage
Adj 2.5V 3.3V 5.0V Adj 2.5V 3.3V 5.0V Adj 2.5V 3.3V 5.0V Adj 2.5V 3.3V 5.0V
Packages
3 Lead TO-220 3 Lead TO-220 3 Lead TO-220 3 Lead TO-220 3 Lead TO-220 3 Lead TO-220 3 Lead TO-220 3 Lead TO-220 3 Lead TO-263 3 Lead TO-263 3 Lead TO-263 3 Lead TO-263 3 Lead TO-263 3 Lead TO-263 3 Lead TO-263 3 Lead TO-263
Corporation
SIGNAL PROCESSING EXCELLENCE
Sipex Corporation
Headquarters and Main Offices: 22 Linnell Circle Billerica, MA 01821 TEL: (978) 667-8700 FAX: (978) 670-9001 e-mail: sales@sipex.com 233 South Hillview Drive Milpitas, CA 95035 TEL: (408) 935-7600 FAX: (408) 934-7500
Sipex Corporation reserves the right to make changes to any products described herein. Sipex does not assume any liability arising out of the application or use of any product or circuit described hereing; neither does it convey any license under its patent rights nor the rights of others.
Rev. 10/30/00

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