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| www.fairchildsemi.com RC1587 3A Adjustable/Fixed Low Dropout Linear Regulator Features * Fast transient response * Low dropout voltage at up to 3A * Load regulation: 0.05% typical * Trimmed current limit * On-chip thermal limiting * Standard TO-220, TO-263, TO-263 center cut, and TO-252 packages Description The RC1587, RC1587-1.5, and RC1587-3.3 are low dropout three-terminal regulators with 3A output current capability. These devices have been optimized for low voltage applications including VTT bus termination, where transient response and minimum input voltage are critical. The RC1587 is ideal for low voltage microprocessor applications requiring a regulated output from 1.5V to 3.6V with an input supply of 5V or less. The RC1587-1.5 offers fixed 1.5V with 3A current capability for GTL+ bus VTT termination. The RC1587-3.3 offers fixed 3.3V current capability for logic IC operation. Current limit is trimmed to ensure specified output current and controlled short-circuit current. On-chip thermal limiting provides protection against any combination of overload and ambient temperature that would create excessive junction temperatures. The RC1587, RC1587-1.5, and RC1587-3.3 are available in the industry-standard TO-220, TO-263, TO-263 center cut, and TO-252 (DPAK) power packages. Applications * Pentium(R) Class GTL+ bus supply * Low voltage logic supply * Post regulator for switching supply Typical Applications VIN = 3.3V 10F + VIN RC1587 VOUT ADJ 124 + 1.5V at 3A 22F 24.9 VIN = 3.3V + 10F RC1587-1.5 VIN VOUT GND + 1.5V at 3A 22F VIN = 5V + 10F RC1587-3.3 VIN VOUT GND + 3.3V at 3A 22F 65-1587-16 Pentium is a registered trademark of Intel Corporation. REV. 1.5 1/12/01 RC1587 PRODUCT SPECIFICATION Pin Assignments RC1587T FRONT VIEW RC1587T-1.5, -3.3V FRONT VIEW RC1587M-1.5, 3.3 FRONT VIEW RC1587M FRONT VIEW 1 2 3 1 2 3 1 2 3 1 2 3 GND OUT IN ADJ OUT IN ADJ OUT IN GND OUT IN 3-Lead Plastic TO-263 JC = 3C/W* 3-Lead Plastic TO-220 JC = 3C/W RC1587MC-1.5, 3.3 FRONT VIEW RC1587MC FRONT VIEW RC1587D-1.5, 3.3 FRONT VIEW RC1587D FRONT VIEW Tab is Out. Tab is Out. 1 2 3 1 2 3 1 2 3 1 2 3 GND GND IN ADJ IN IN ADJ IN 3-Lead Plastic TO-252 JC = 3C/W* 3-Lead Plastic TO-263 Center Cut JC = 3C/W* * JA can vary from 20C/W to >40C/W with various mounting techniques. Absolute Maximum Ratings Parameter VIN Operating Junction Temperature Range Storage Temperature Range Lead Temperature (Soldering, 10 sec.) 0 -65 Min. Max. 7 125 150 300 Unit V C C C 2 REV. 1.5 PRODUCT SPECIFICATION RC1587 Electrical Characteristics Tj = 25C unless otherwise specified. The * denotes specifications which apply over the specified operating temperature range. Parameter Reference Voltage Output Voltage4 Output Voltage5 Line Regulation1, 2 Load Regulation1, 2 Dropout Voltage Current Limit Adjust Pin Current3 Adjust Pin Current Change3 1.5V (VIN - VOUT) 5.75V, 10mA IOUT 3A 1.5V (VIN - VOUT) 5.75V VIN = 5V f = 120Hz, COUT = 22F Tantalum, (VIN - VOUT) = 3V, IOUT = 3A TA = 25C, 30ms pulse * TA = 125C, 1000 hrs. TA = 25C, 10Hz f 10kHz TO-220 TO-263, TO-252 3 Conditions 1.5V (VIN - VOUT) 5.75V, 10mA IOUT 3A 3.3V VIN 7V 10mA IOUT 3A 5.1V VIN 7V 10mA IOUT 3A (VOUT + 1.5V) VIN 7V, IOUT = 10mA (VIN - VOUT) = 3V 10mA IOUT 3A VREF = 1%, IOUT = 3A (VIN - VOUT) = 2V * * * * * * * * * * * Min. 1.225 (-2%) 1.47 3.234 Typ. 1.250 1.5 3.3 0.005 0.05 1.150 Max 1.275 (+2%) 1.53 3.366 0.2 0.5 1.300 120 5 Units V V V % % V A A A mA 3.1 4 35 0.2 Minimum Load Current Quiescent Current Ripple Rejection Thermal Regulation Temperature Stability Long-Term Stability RMS Output Noise (% of VOUT) Thermal Resistance, Junction to Case Thermal Shutdown 10 4 60 72 0.004 0.5 0.03 0.003 3 3 150 1.0 0.02 13 mA dB %/W % % % C/W C/W C Notes: 1. See thermal regulation specifications for changes in output voltage due to heating effects. Load and line regulation are measured at a constant junction temperature by low duty cycle pulse testing. 2. Line and load regulation are guaranteed up to the maximum power dissipation (18W). Power dissipation is determined by input/output differential and the output currrent. Guaranteed maximum output power will not be available over the full input/ output voltage range. 3. RC1587 only. 4. RC1587-1.5 only. 5. RC1587-3.3 only. REV. 1.5 3 RC1587 PRODUCT SPECIFICATION Typical Performance Characteristics 1.5 OUTPUT VOLTAGE DEVIATION (%) 0.10 I = 3A 1.4 DROPOUT VOLTAGE (V) 1.3 1.2 1.1 1.0 0.9 T=25C 0.8 65-1587-03 0.05 0 T=0C T=125C -0.05 -0.10 65-1587-04 0.7 0.6 0.5 0 0.5 1 1.5 2 2.5 OUTPUT CURRENT (A) -0.15 3.0 -0.20 -75 -50 -25 0 25 50 75 100 125 150 175 JUNCTION TEMPERATURE (C) Figure 1. Dropout Voltage vs. Output Current Figure 2. Load Regulation vs. Temperature 1.275 3.70 1.270 3.65 REFERENCE VOLTAGE (V) 1.260 1.255 1.250 1.245 1.240 65-1585-05 REFERENCE VOLTAGE (V) 1.265 VOUT SET WITH 1% RESISTORS VOUT = 3.6V1 3.60 3.55 3.50 3.45 3.40 3.35 3.30 3.25 3.20 -75 -50 -25 0 Note: 1. RC1587 Only 2. RC1587, -3.3 VOUT = 3.3V2 1.230 1.225 -75 -50 -25 0 25 50 75 100 125 150 175 25 50 75 100 125 150 175 JUNCTION TEMPERATURE (C) JUNCTION TEMPERATURE (C) Figure 3. Reference Voltage vs. Temperature Figure 4. Output Voltage vs. Temperature 5 MINIMUM LOAD CURRENT (mA) 100 90 Note: 1. RC1587 Only 4 ADJUST PIN CURRENT (A) 80 70 60 50 40 30 65-1587-08 3 2 65-1587-07 1 20 10 0 -75 -50 -25 0 0 -75 -50 -25 0 25 50 75 100 125 150 175 25 50 75 100 125 150 175 JUNCTION TEMPERATURE (C) JUNCTION TEMPERATURE (C) Figure 5. Minimum Load Current vs. Temperature Figure 6. Adjust Pin Current vs. Temperature 4 65-1587-06 1.235 REV. 1.5 PRODUCT SPECIFICATION RC1587 Typical Performance Characteristics (continued) 5.0 90 80 SHORT-CIRCUIT CURRENT (A) RIPPLE REJECTIONS (dB) 4.5 70 60 50 40 30 20 10 0 10 65-1587-10 4.0 3.5 65-1587-09 (VIN - VOUT) 3V 0.5V VRIPPLE 2V IOUT = 3A 100 1K FREQUENCY (Hz) 10K 3.0 -75 -50 -25 0 25 50 75 100 125 150 175 100K JUNCTION TEMPERATURE (C) Figure 7. Short-Circuit Current vs. Temperature Figure 8. Ripple Rejection vs. Frequency 20 15 POWER (W) 10 5 65-1587-11 0 50 60 70 80 90 100 110 120 130 140 150 CASE TEMPERATURE (C) Figure 9. Maximum Power Dissipation REV. 1.5 5 RC1587 PRODUCT SPECIFICATION Applications Information General The RC1587, RC1587-1.5, and RC1587-3.3 are three-terminal regulators optimized for GTL+ VTT termination applications. These devices are short-circuit protected, and offer thermal shutdown to turn off the regulator when the junction temperature exceeds about 150C. The RC1587 series provides low dropout voltage and fast transient response. Frequency compensation uses capacitors with low ESR while still maintaining stability. This is critical in addressing the needs of low voltage high speed microprocessor buses like GTL+. D1 1N4002 (OPTIONAL) RC1587 VIN C1 10F + IN ADJ + CADJ R2 OUT R1 + VOUT C2 22F Stability The RC1587 series require an output capacitor as a part of the frequency compensation. It is recommended to use a 22F solid tantalum or a 100F aluminum electrolytic on the output to ensure stability. The frequency compensation of these devices optimizes the frequency response with low ESR capacitors. In general, it is suggested to use capacitors with an ESR of <300m. It is also recommended to use bypass capacitors such as a 22F tantalum or a 100F aluminum on the adjust pin of the RC1587 for low ripple and fast transient response. When these bypassing capacitors are not used at the adjust pin, larger values of output capacitors provide equally good results. D1 1N4002 (OPTIONAL) RC1587-1.5, -3.3 VIN C1 10F + IN GND OUT + VOUT C2 22F 65-1587-13 Figure 10. Optional Protection Protection Diodes In normal operation, the RC1587 series does not require any protection diodes. For the RC1587, internal resistors limit internal current paths on the adjust pin. Therefore, even with bypass capacitors on the adjust pin, no protection diode is needed to ensure device safety under shortcircuit conditions. A protection diode between the input and output pins is usually not needed. An internal diode between the input and output pins on the RC1587 series can handle microsecond surge currents of 50A to 100A. Even with large value output capacitors it is difficult to obtain those values of surge currents in normal operation. Only with large values of output capacitance, such as 1000F to 5000F, and with the input pin instantaneously shorted to ground can damage occur. A crowbar circuit at the input can generate those levels of current; a diode from output to input is then recommended, as shown in Figure 10. Usually, normal power supply cycling or system "hot plugging and unplugging" will not generate current large enough to do any damage. The adjust pin can be driven on a transient basis 7V with respect to the output, without any device degradation. As with any IC regulator, exceeding the maximum input-tooutput voltage differential causes the internal transistors to break down and none of the protection circuitry is then functional. Ripple Rejection In applications that require improved ripple rejection, a bypass capacitor from the adjust pin of the RC1587 to ground reduces the output ripple by the ratio of VOUT/1.25V. The impedance of the adjust pin capacitor at the ripple frequency should be less than the value of R1 (typically in the range of 100 to 120) in the feedback divider network in Figure 10. Therefore, the value of the required adjust pin capacitor is a function of the input ripple frequency. For example, if R1 equals 100 and the ripple frequency equals 120Hz, the adjust pin capacitor should be 22F. At 10kHz, only 0.22F is needed. Output Voltage The RC1587 regulator develops a 1.25V reference voltage between the output pin and the adjust pin (see Figure 11). Placing a resistor R1 between these two terminals causes a constant current to flow through R1 and down through R2 to set the overall output voltage. Normally, this current is the specified minimum load current of 10mA. The current out of the adjust pin adds to the current from R1 and is typically 35A. Its output voltage contribution is small and only needs consideration when very precise output voltage setting is required. 6 REV. 1.5 PRODUCT SPECIFICATION RC1587 RC1587 VIN + IN C1 10F ADJ IADJ 35A VOUT = VREF (1 + R2/R1) + IADJ (R2) OUT VREF R1 + VOUT C2 22F RC1587 VIN IN ADJ OUT RP PARASITIC LINE RESISTANCE R2 65-1587-14 R1* RL * CONNECT R1 TO CASE CONNECT R2 TO LOAD R2* Figure 11. Basic Regulator Circuit Load Regulation It is not possible to provide true remote load sensing because the RC1587 series are three-terminal devices. Load regulation is limited by the resistance of the wire connecting the regulators to the load. Load regulation per the data sheet specification is measured at the bottom of the package. For fixed voltage devices, negative side sensing is a true Kelvin connection with the ground pin of the device returned to the negative side of the load. This is illustrated in Figure 12. RC1587-1.5, -3.3 VIN IN GND OUT RL RP PARASITIC LINE RESISTANCE 65-1587-15 Figure 13. Connection for Best Load Regulation Thermal Considerations The RC1587 series protect themselves under overload conditions with internal power and thermal limiting circuitry. However, for normal continuous load conditions, do not exceed maximum junction temperature ratings. It is important to consider all sources of thermal resistance from junction-to-ambient. These sources include the junction-to-case resistance, the case-to-heat sink interface resistance, and the heat sink resistance. Thermal resistance specifications have been developed to more accurately reflect device temperature and ensure safe operating temperatures. For example, look at using an RC1587T to generate 3A @ 1.5V 2% from a 3.3V source (3.2V to 3.6V). Assumptions: * * * * * VIN = 3.6V worst case VOUT = 1.46V worst case IOUT = 3A continuous TA = 70C Case-to-Ambient = 3C/W (assuming both a heatsink and a thermally conductive material) The power dissipation in this application is: PD = (VIN - VOUT) * (IOUT) = (3.6 - 1.46) * (3) = 6.42W From the specification table: TJ = TA + (PD) * (Case-to-Ambient + JC) = 70 + (6.42) * (3 + 3) = 109C The junction temperature is below the maximum rating. 65-1587-17 Figure 12. Connection for Best Load Regulation For adjustable voltage devices, negative side sensing is a true Kelvin connection with the bottom of the output divider returned to the negative side of the load. The best load regulation is obtained when the top of resistor divider R1 connects directly to the regulator output and not to the load. Figure 13 illustrates this point. If R1 connects to the load, then the effective resistance between the regulator and the load would be: RP x (1 + R2/R1), RP = Parasitic Line Resistance The connection shown in Figure 13 does not multiply RP by the divider ratio. As an example, RP is about four milliohms per foot with 16-gauge wire. This translates to 4mV per foot at 1A load current. At higher load currents, this drop represents a significant percentage of the overall regulation. It is important to keep the positive lead between the regulator and the load as short as possible and to use large wire or PC board traces. REV. 1.5 7 RC1587 PRODUCT SPECIFICATION Junction-to-case thermal resistance is specified from the IC junction to the bottom of the case directly below the die. This is the lowest resistance path for heat flow. Proper mounting ensures the best thermal flow from this area of the package to the heat sink. Use of a thermally conductive material at the case-to-heat sink interface is recommended. Use a thermally conductive spacer if the case of the device must be electrically isolated and include its contribution to the total thermal resistance. The cases of the RC1587 series are directly connected to the output of the device. VIN 3.3V C1 10F U1 RC1587 VIN + ADJ + C2 100F VOUT R1 124 R2 24.9 + VOUT 1.5V C3 100F 65-1587-18 Figure 14. Application Circuit (RC1587) Table 1. Bill of Materials for Application Circuit for the RC1587 Item C1 C2, C3 R1 R2 U1 Quantity 1 2 1 1 1 Manufacturer Xicon Xicon Generic Generic Fairchild RC1587T Part Number L10V10 L10V100 Description 10F, 10V Aluminum 100F, 10V Aluminum 124, 1% 24.9, 1% 3A Regulator VIN 3.3V C1 10F U1 RC1587-1.5 VIN + VOUT GND + VOUT 1.5V C3 100F 65-1587-19 Figure 15. Application Circuit (RC1587-1.5) Table 2. Bill of Materials for Application Circuit for the RC1587-1.5 Item C1 C3 U1 Quantity 1 1 1 Manufacturer Xicon Xicon Fairchild Part Number L10V10 L10V100 RC1587T-1.5 Description 10F, 10V Aluminum 100F, 10V Aluminum 3A Regulator 8 REV. 1.5 PRODUCT SPECIFICATION RC1587 VIN 3.3V C1 10F U1 RC1587-3.3 VIN + VOUT GND + VOUT 3.3V C3 100F 65-1587-20 Figure 16. Application Circuit (RC1587-3.3) Table 3. Bill of Materials for Application Circuit for the RC1587-1.5 Item C1 C3 U1 Quantity 1 1 1 Manufacturer Xicon Xicon Fairchild Part Number L10V10 L10V100 RC1587T-3.3 Description 10F, 10V Aluminum 100F, 10V Aluminum 3A Regulator REV. 1.5 9 RC1587 PRODUCT SPECIFICATION Mechanical Dimensions 3-Lead TO-263 Package Inches Min. A b b2 c2 D E e L L1 L2 R .160 .020 Max. .190 .036 Millimeters Min. 4.06 0.51 Max. 4.83 0.91 Notes: 1. Dimensions are exclusive of mold flash and metal burrs. 2. Standoff-height is measured from lead tip with ref. to Datum -B-. 3. Foot length is measured with ref. to Datum -A- with lead surface (at inner R). 4. Dimensiuon exclusive of dambar protrusion or intrusion. 5. Formed leads to be planar with respect to one another at seating place -C-. Symbol Notes .049 .051 .045 .055 .340 .380 .380 .405 .100 BSC .575 .090 -- .017 0 .625 .110 .055 .019 8 1.25 1.30 1.14 1.40 8.64 9.65 9.65 10.29 2.54 BSC 14.61 2.29 -- 0.43 0 15.88 2.79 1.40 0.78 8 E @PKG/ @HEATSINK L2 c2 D L b2 E-PIN R (2 PLCS) L1 b e -B- -A- A -C- 10 REV. 1.5 PRODUCT SPECIFICATION RC1587 Mechanical Dimensions (continued) 3-Lead TO-263 Center Cut Package Inches Min. A b b2 c2 D E e L L1 L2 L3 R .160 .020 Max. .190 .036 Millimeters Min. 4.06 0.51 Max. 4.83 0.91 Notes: 1. Dimensions are exclusive of mold flash and metal burrs. 2. Standoff-height is measured from lead tip with ref. to Datum -B-. 3. Foot length is measured with ref. to Datum -A- with lead surface (at inner R). 4. Dimensiuon exclusive of dambar protrusion or intrusion. 5. Formed leads to be planar with respect to one another at seating place -C-. Symbol Notes .049 .051 .045 .055 .340 .380 .380 .405 .100 BSC .575 .090 -- .050 .017 0 .625 .110 .055 .070 .019 8 1.25 1.30 1.14 1.40 8.64 9.65 9.65 10.29 2.54 BSC 14.61 2.29 -- 1.27 0.43 0 15.88 2.79 1.40 1.78 0.78 8 E @PKG/ @HEATSINK L2 c2 D L b2 E-PIN R (2 PLCS) L1 L3 b e -B- -A- A -C- REV. 1.5 11 RC1587 PRODUCT SPECIFICATION Mechanical Dimensions (continued) 3-Lead TO-220 Package Inches Min. A b b1 c1 oP D E e e1 e3 F H1 J1 L L1 Q Max. Millimeters Min. Max. Symbol Notes .140 .190 .015 .040 .045 .070 .014 .022 .139 .161 .560 .650 .380 .420 .090 .110 .190 .210 .045 -- .020 .055 .230 .270 .080 .115 .500 .580 .250 BSC .100 .135 3 7 3.56 4.83 .38 1.02 1.14 1.78 .36 .56 3.53 4.09 14.22 16.51 9.65 10.67 2.29 2.79 4.83 5.33 1.14 -- .51 1.40 5.94 6.87 2.04 2.92 12.70 14.73 6.35 BSC 2.54 3.43 3 7 Notes: 1. Dimension c1 apply for lead finish. H1 L e3 e e1 E b1 Q b L1 E-PIN oP (5X) c1 J1 D A F 12 REV. 1.5 PRODUCT SPECIFICATION RC1587 Mechanical Dimensions (continued) 3-Lead TO-252 Package Notes: Notes 1. 2. 3. 4. 5. Dimensions are exclusive of mold flash and metal burrs. Stand off-height is measured from lead tip with ref. to Datum -B-. Foot length is measured with ref. to Datum -A- with lead surface (at inner R). Dimension exclusive of dambar protrusion or intrusion. Formed leads to be planar with respect to one another at seating place -C-. Symbol A b b2 c2 D E e L L1 L2 R Inches Min. Max. Millimeters Min. Max. .086 .094 .025 .035 .030 .045 .018 .023 .210 .231 .250 .265 .090 BSC .370 .410 .020 -- .055 .080 .018 .023 0 8 2.19 2.38 0.64 0.88 0.76 1.17 0.76 0.58 5.33 5.88 6.35 6.73 2.285 BSC 9.40 10.72 0.51 -- 1.40 2.03 0.46 0.58 0 8 E @PKG/ @HEATSINK L2 c2 D L b2 E-PIN R (2 PLCS) L1 b e -B- -A- A -C- REV. 1.5 13 RC1587 PRODUCT SPECIFICATION Ordering Information Product Number RC1587M RC1587MC RC1587T RC1587D RC1587M-1.5 RC1587MC-1.5 RC1587T-1.5 RC1587D-1.5 RC1587M-3.3 RC1587MC-3.3 RC1587T-3.3 RC1587D-3.3 Package TO-263 TO-263 center cut TO-220 TO-252 TO-263 TO-263 center cut TO-220 TO-252 TO-263 TO-263 center cut TO-220 TO-252 LIFE SUPPORT POLICY FAIRCHILD'S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and (c) whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury of the user. 2. A critical component in any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. www.fairchildsemi.com 1/12/01 0.0m 001 Stock#DS30001587 1998 Fairchild Semiconductor Corporation |
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