www.fairchildsemi.com RC1585 5A Adjustable/Fixed Low Dropout Linear Regulator Features Description • Fast transient response • Low dropout voltage at up to 5A • Load regulation: 0.05% typical • Trimmed current limit • On-chip thermal limiting • Standard TO-220 and TO-263 packages The RC1585 and RC1585-1.5 are low dropout three-terminal regulators with 5A 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 RC1585 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 RC1585-1.5 offers fixed 1.5V with 5A current capabilities for GTL+ bus VTT termination. Applications 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. • Pentium® Pro and Pentium II GTL+ bus supply • Low voltage logic supply • Battery-powered circuitry • Post regulator for switching supply The RC1585 series regulators are available in the industry-standard TO-220 and TO-263 power packages. Typical Applications VIN = 3.3V 10µF + RC1585 VOUT VIN ADJ 1.5V at 5A + 22µF 124Ω 24.9Ω VIN = 3.3V 10µF + RC1585-1.5 VOUT VIN GND Pentium is a registered trademark of Intel Corporation 1.0.2 1.5V at 5A + 22µF Rev. RC1585 PRODUCT SPECIFICATION Pin Assignments RC1585M-1.5 RC1585M FRONT VIEW FRONT 1 2 3 1 GND OUT IN ADJ 2 OUT RC1585T RC1585T-1.5 FRONT VIEW FRONT VIEW 1 3 2 1 3 2 IN ADJ OUT 3-Lead Plastic TO-263 ΘJA=30°C/W* IN GND OUT IN 3-Lead Plastic TO-220 ΘJA=50°C/W *With package soldered to 0.5 square inch copper area over backside ground plane or internal power plane. ΘJA can vary from 20°C/W to >40°C/W with other mounting techniques. Absolute Maximum Ratings Parameter VIN Operating Junction Temperature Range Control Section Power Transistor Storage Temperature Range Lead Temperature (Soldering, 10 sec.) 2 3 Min. Max. 7 Unit V 0 0 -65 125 150 150 300 °C °C °C °C RC1585 PRODUCT SPECIFICATION Electrical Characteristics Preconditioning: 100% Thermal Limit Functional Test. TJ=25°C unless otherwise specified. The • denotes specifications which apply over the specified operating temperature range. Parameter Reference Voltage3 Output Voltage4 Line Regulation1,2 Load Regulation1,2,3 Dropout Voltage Current Limit Adjust Pin Current3 Adjust Pin Current Change3 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 Conditions 1.5V≤ (VIN-VOUT) ≤ 5.75V, 10mA ≤ IOUT ≤ 5A 3V≤VIN ≤7V 10mA ≤ IOUT ≤ 5A (VOUT + 1.5V) ≤ VIN ≤ 7V, IOUT = 10mA (VIN - VOUT) = 3V, 10mA ≤ IOUT ≤ 5A ∆VREF = 1%, IOUT = 5A (VIN - VOUT) = 2V 1.5V ≤ (VIN - VOUT) ≤ 5.75V, 10mA ≤ IOUT ≤ 5A 1.5V ≤ (VIN - VOUT) ≤ 5.75V VIN = 5V f = 120Hz, COUT = 22µF Tantalum, (VIN - VOUT) = 3V, IOUT = 5A TA = 25°C, 30ms pulse Units V 1.5 Max. 1.275 (+2%) 1.53 • 0.005 0.2 % • 0.05 0.5 % • • • • 1.150 5.5 35 0.2 1.300 V A µA µA 4 72 13 0.004 0.5 0.03 0.003 0.02 • • • • 5.1 Typ. 1.250 120 5 10 60 • TA = 125°C, 1000 hrs. TA = 25°C, 10Hz ≤ f ≤ 10kHz Min. 1.225 (-2%) 1.47 Control Section Power Transistor 1.0 0.7 3.0 150 V mA mA dB %/W % % % °C/W °C/W °C Notes: 1. 2. 3. 4. 3 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. Line and load regulation are guaranteed up to the maximum power dissipation (18W). Power dissipation is determined by input/output differential and the output current. Guaranteed maximum output power will not be available over the full input/output voltage range. RC1585 only. RC1585-1.5 only. RC1585 PRODUCT SPECIFICATION 1.5 1.4 1.3 1.2 1.1 1.0 0.9 0.8 0.7 0.6 0.5 OUTPUT VOLTAGE DEVIATION (%) DROPOUT VOLTAGE (V) Typical Performance Characteristics T=0°C T=25°C T=125°C 0 1 2 3 4 5 OUTPUT CURRENT (A) OUTPUT VOLTAGE (V) REFERENCE VOLTAGE 3 2 1 0 -75 -50 -25 0 25 50 75 100 125 150 175 TEMPERATURE (°C) Figure 5. Minimum Load Current vs. Temperature 0 -0.05 -0.10 -0.15 -0.20 -75 –50 –25 0 25 50 75 100 125 150 175 OUT 1 OUT 1 OUT 1 OUT TEMPERATURE (°C) Figure 4. Output Voltage vs. Temperature 100 Note: 90 1. RC1585 only 80 70 60 50 40 30 20 10 0 -75 -50 -25 0 25 50 75 100 125 150 175 TEMPERATURE (°C) Figure 6. Adjust Pin Current vs. Temperature Typical Performance Characteristics (continued) 8 4 7 1 OUT ADJUST PIN CURRENT (µA) MINIMUM LOAD CURRENT (mA) 4 0.05 3.70 V SET WITH 1% RESISTORS V = 3.6V 3.65 3.60 3.55 V = 3.45V 3.50 3.45 V = 3.38V 3.40 V = 3.3V 3.35 3.30 Note: 1. RC1585 Only 3.25 3.20 -75 -50 -25 0 25 50 75 100 125 150 175 TEMPERATURE (°C) Figure 3. Reference Voltage vs. Temperature 5 ∆I=5A TEMPERATURE (°C) Figure 2. Load Regulation vs. Temperature Figure 1. Dropout Voltage vs. Output current 1.250 1.245 1.240 1.235 1.230 1.225 1.220 1.215 1.210 1.205 1.200 -75 -50 -25 0 25 50 75 100 125 150 175 0.10 RC1585 PRODUCT SPECIFICATION RIPPLE REJECTIONS (dB) SHORT-CIRCUIT CURRENT (A) 90 80 70 60 50 40 30 20 10 0 -75 -50 -25 0 25 50 75 100 125 150 175 TEMPERATURE (°C) Figure 7. Short-Circuit Current vs. Temperature (VIN – VOUT) ≤ 3V 0.5V ≤ VRIPPLE ≤ 2V IOUT = 5A 10 POWER (W) 100K Figure 8. Ripple Rejection vs. Frequency 20 15 10 5 0 50 60 70 80 90 100 110 120 130 140 150 CASE TEMPERATURE Figure 9. Maximum Power Dissipation 5 100 1K 10K FREQUENCY (Hz) RC1585 PRODUCT SPECIFICATION Applications Information General The RC1585 and RC1585-1.5 are three-terminal regulators optimized for GTL+ VTT termination and logic applications. These devices are short-circuit protected, safe area protected, and offer thermal shutdown to turn off the regulator when the junction temperature exceeds about 150°C. The RC1585 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+. VIN 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-to-output voltage differential causes the internal transistors to break down and none of the protection circuitry is then functional. D1 1N4002 (OPTIONAL) IN C1 + 10µF Stability The RC1585 series requires an output capacitor as a part of the frequency compensation. It is recommended to use a 22µF solid tantalum or a 100 µF 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 <1Ω. It is also recommended to use bypass capacitors such as a 22µF tantalum or a 100µF aluminum on the adjust pin of the RC1585 for low ripple and fast transient response. When these bypassing capacitors are not used at the adjust pin, smaller values of output capacitors provide equally good results. RC1585 OUT ADJ VOUT + R1 + CADJ C2 22µF R2 D1 1N4002 (OPTIONAL) VIN C1 + 10µF RC1585-1.5 IN OUT GND VOUT + C2 22µF Protection Diodes In normal operation, the RC1585 series does not require any protection diodes. For the RC1585, 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 short-circuit conditions. A protection diode between the input and output pins is usually not needed. An internal diode between the input and the output pins on the RC1585 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 1000µF to 5000µF, 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. 6 Figure 10. Optional Protection Ripple Rejection In applications that require improved ripple rejection, a bypass capacitor from the adjust pin of the RC1585 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 100Ω to 120Ω) 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 100Ω and the ripple frequency equals 120Hz, the adjust pin capacitor should be 22µF. At 10kHz, only 0.22µF is needed. Output Voltage The RC1585 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. RC1585 PRODUCT SPECIFICATION The current out of the adjust pin adds to the current from R1 and is typically 35µA. Its output voltage contribution is small and only needs consideration when a very precise output voltage setting is required. IN VIN C1 + 10µF RC1585 OUT ADJ VOUT + VREF R1 IADJ 35µA C2 22µF 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. R2 VOUT = VREF (1 + R2/R1) + IADJ (R2) VIN Figure 11. Basic Regulator Circuit IN RC1585 OUT ADJ RP Parasitic Line Resistance ∫∫ R1* Load Regulation It is not possible to provide true remote load sensing because the RC1585 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. RL *Connect R1 to case Connect R2 to load R2* ∫∫ ∫∫ Figure 13. Connection for Best Load Regulation 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. RP Parasitic Line Resistance VIN RC1585 -1.5 IN OUT GND ∫∫ RL ∫∫ ∫∫ 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 the 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 × (1 + R2/R1), RP = Parasitic Line Resistance 7 Thermal Considerations The RC1585 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-toambient. 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. The electrical characteristics section provides a separate thermal resistance and maximum junction temperature for both the control circuitry and the power transistor. Calculate the maximum junction temperature for both sections to ensure that both thermal limits are met. For example, look at using an RC1585T to generate 5A @ 1.5V ± 2% from a 3.3V source (3.2V to 3.6V). RC1585 PRODUCT SPECIFICATION Assumptions: • • • 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 RC1585 series are directly connected to the output of the device. Vin = 3.6V worst case VOUT = 1.46V worst case IOUT = 5A continuous TA = 60°C ΘCase-to-Ambient = 5°C/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) * (5) = 10.7W From the specification table, for the power section: TJ = TA + (PD) * (ΘCase-to-Ambient + ΘJC) = 60 + (10.7) * (5 + 3) = 146°C For the control section: TJ = TA + (PD) * (ΘCase-to-Ambient + ΘJC) = 60 + (10.7) * (5 + 0.7) = 121°C In each case, the junction temperature is below the maximum rating. U1 VIN = 3.3V + C1 10µF RC1585 VOUT VIN ADJ + VOUT 1.5V C3 100µF R1 124Ω + C2 100µF R2 24.9Ω Figure 14. Application Circuit (RC1585) Table 1. Bill of Materials for Application Circuit for the RC1585 Item C1 C2, C3 R1 R2 U1 8 Quantity 1 2 1 1 1 Manufacturer Xicon Xicon Generic Generic Fairchild Part Number L10V10 L10V100 RC1585T Description 10µF, 10V Aluminum 100µF, 10V Aluminum 124Ω, 1% 24.9Ω, 1% 5A Regulator RC1585 PRODUCT SPECIFICATION U1 VIN = 3.3V + C1 10µF RC1585-1.5 VOUT VIN GND + C3 100µF VOUT 1.5V Figure 15. Application Circuit (RC1585-1.5) Table 2. Bill of Materials for Application Circuit for the RC1585-1.5 Item C1 C3 U1 9 Quantity 1 1 1 Manufacturer Xicon Xicon Fairchild Part Number L10V10 L10V100 RC1585T-1.5 Description 10µF, 10V Aluminum 100µF, 10V Aluminum 5A Regulator RC1585 PRODUCT SPECIFICATION Mechanical Dimensions 3-Lead TO-263 Package Symbol Inches Min. Max. .160 .190 .020 .039 .049 .051 .045 .055 .340 .380 .380 .405 .100 BSC .575 .625 .090 .100 .055 .017 .019 0° 8° A b b2 c2 D E e L L1 L2 R α Millimeters Min. Max. 4.06 4.83 0.51 0.99 1.25 1.30 1.14 1.40 8.64 9.65 9.65 10.29 2.54 BSC 14.61 10.88 2.29 2.79 1.40 0.43 0.48 0° 8° E @PKG/ @HEATSINK Notes: 1. 2. 3. 4. 5. Dimensions are exclusive of mold flash and metal burrs. Standoff-height is measured from lead tip with ref. to Datum –B-. Foot length is measured with ref. to Datum –Awith 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-. L2 c2 D E-PIN L b2 R (2PLCS) b e L1 -B- A -C- 10 -A- RC1585 PRODUCT SPECIFICATION Mechanical Dimensions (continued) 3-Lead TO-220 Package Symbol Inches Min. Max. .140 .190 .015 .040 .045 .070 .014 .022 .139 .161 .560 .650 .380 .420 .090 .110 .190 .210 .045 .020 .055 .230 .270 .060 .115 .500 .580 .250 BSC 1.00 1.35 3° 7° A b b1 c1 ∅P D E e e1 e3 F H1 J1 L L1 Q α Millimeters Min. Max. 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 Q b1 e E e1 b E-PIN L1 ∅P α (5X) c1 J1 D A F 11 RC1585 PRODUCT SPECIFICATION Ordering Information Product Number RC1585M RC1585T RC1585M-1.5 RC1585T-1.5 Package TO-263 TO-220 TO-263 TO-220 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. 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