www.fairchildsemi.com RC1585 5A Adjustable/Fixed Low Dropout Linear Regulator Features Description • • • • • • 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. 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, TO-263, TO-263 center cut and TO-252 packages Applications • Pentium® class GTL+ bus supply • Low voltage logic supply • Post regulator for switching supply 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 RC1585 series regulators are available in the industrystandard TO-220, TO-263, TO-263 center cut and TO-252 power packages. Typical Applications VIN VIN = 3.3V 10µF + RC1585 VOUT 1.5V at 5A + ADJ 124Ω 22µF 24.9Ω RC1585-1.5 VIN VOUT VIN = 3.3V + 10µF GND 1.5V at 5A + 22µF 65-1585-01a Pentium is a registered trademark of Intel Corporation. REV. 1.1.2 1/12/01 RC1585 PRODUCT SPECIFICATION Pin Assignments RC1585M-1.5 RC1585M FRONT VIEW FRONT VIEW RC1585T RC1585T-1.5 FRONT VIEW FRONT VIEW 1 1 2 3 1 GND OUT IN 2 2 3 1 2 3 3 ADJ OUT IN ADJ OUT IN 3-Lead Plastic TO-263 θJC = 3°C/W* GND OUT IN 3-Lead Plastic TO-220 θJC = 3°C/W RC1585MC-1.5 RC1585MC FRONT VIEW FRONT VIEW RC1585D-1.5 RC1585D FRONT VIEW FRONT VIEW Tab is Out. 1 2 GND 3 1 IN ADJ 2 3 IN Tab is Out. 1 GND 3-Lead Plastic TO-263 Center Cut θJC = 3°C/W* 2 3 1 IN ADJ 2 3 IN 3-Lead Plastic TO-252 θJC = 3°C/W* * θJA can vary from 20°C/W to >40°C/W with various mounting techniques. 65-1585-02 Absolute Maximum Ratings Parameter Min. Max. Unit 7 V 0 125 °C -65 150 °C 300 °C VIN Operating Junction Temperature Range Storage Temperature Range Lead Temperature (Soldering, 10 sec.) 2 REV. 1.1.2 PRODUCT SPECIFICATION RC1585 Electrical Characteristics Tj = 25°C unless otherwise specified. The • denotes specifications which apply over the specified operating temperature range. Parameter Conditions Min. Typ. Max Units Reference Voltage 1.5V ≤ (VIN – VOUT) ≤ 5.75V, 10mA ≤ IOUT ≤ 5A • 1.225 (-2%) 1.250 1.275 (+2%) V Output Voltage4 3V ≤ VIN ≤ 7V 10mA ≤ IOUT ≤ 5A • 1.47 1.5 1.53 V Line Regulation1, 2 (VOUT + 1.5V) ≤ VIN ≤ 7V, IOUT = 10mA • 0.005 0.2 % Load Regulation1, 2, 3 (VIN – VOUT) = 3V, 10mA ≤ IOUT ≤ 5A • 0.05 0.5 % Dropout Voltage ∆VREF = 1%, IOUT = 5A • 1.150 1.300 V Current Limit (VIN – VOUT) = 2V • 3 5.1 5.5 A Adjust Pin Current3 • 35 120 µA Adjust Pin Current Change3 1.5V ≤ (VIN – VOUT) ≤ 5.75V, 10mA ≤ IOUT ≤ 5A • 0.2 5 µA Minimum Load Current 1.5V ≤ (VIN – VOUT) ≤ 5.75V • Quiescent Current VIN = 5V • Ripple Rejection f = 120Hz, COUT = 22µF Tantalum, (VIN – VOUT) = 3V, IOUT = 5A Thermal Regulation TA = 25°C, 30ms pulse mA 4 60 13 72 0.004 • Temperature Stability 10 mA dB 0.02 0.5 %/W % Long-Term Stability TA = 125°C, 1000 hrs. 0.03 RMS Output Noise (% of VOUT) TA = 25°C, 10Hz ≤ f ≤ 10kHz 0.003 % Thermal Resistance, Junction to Case TO-220 3 °C/W TO-263, TO-252 3 °C/W 150 °C Thermal Shutdown 1.0 % 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. RC1585 only. 4. RC1585-1.5 only. REV. 1.1.2 3 RC1585 PRODUCT SPECIFICATION Typical Performance Characteristics 0.10 1.5 OUTPUT VOLTAGE DEVIATION (%) 1.2 1.1 1.0 T=0°C 0.9 T=125°C T=25°C 0.8 0.7 0.6 0.5 0 1 2 3 4 ∆I = 5A 0.05 0 -0.05 -0.10 65-1585-04 1.3 65-1585-03 DROPOUT VOLTAGE (V) 1.4 -0.15 -0.20 -75 -50 -25 5 0 25 50 75 100 125 150 175 JUNCTION TEMPERATURE (°C) OUTPUT CURRENT (A) Figure 1. Dropout Voltage vs. Output Current Figure 2. Load Regulation vs. Temperature 1.275 3.70 1.270 3.65 1.265 3.60 REFERENCE VOLTAGE (V) 1.255 1.250 1.245 1.240 1.235 1.230 1.225 -75 -50 -25 0 3.55 3.50 3.45 3.40 3.35 3.30 Note: 1. RC1585 Only 3.20 -75 -50 -25 0 25 50 75 100 125 150 175 JUNCTION TEMPERATURE (°C) JUNCTION TEMPERATURE (°C) Figure 4. Output Voltage vs. Temperature 5 100 Note: 1. RC1585 Only 3 2 1 0 -75 -50 -25 0 25 50 75 100 125 150 175 JUNCTION TEMPERATURE (°C) Figure 5. Minimum Load Current vs. Temperature 80 70 60 50 40 30 20 65-1585-08 4 ADJUST PIN CURRENT (µA) 90 65-1585-07 MINIMUM LOAD CURRENT (mA) 1 VOUT = 3.3V 3.25 25 50 75 100 125 150 175 Figure 3. Reference Voltage vs. Temperature 4 1 VOUT = 3.6V 65-1585-06 1.260 65-1585-05 REFERENCE VOLTAGE (V) VOUT SET WITH 1% RESISTORS 10 0 -75 -50 -25 0 25 50 75 100 125 150 175 JUNCTION TEMPERATURE (°C) Figure 6. Adjust Pin Current vs. Temperature REV. 1.1.2 PRODUCT SPECIFICATION RC1585 Typical Performance Characteristics (continued) 90 8.0 6.0 5.0 4.0 -75 -50 -25 0 25 50 75 100 125 150 175 70 60 50 40 30 20 10 (VIN – VOUT) ≤ 3V 0.5V ≤ VRIPPLE ≤ 2V IOUT = 5A 0 10 100 1K 65-1585-10 RIPPLE REJECTIONS (dB) 7.0 65-1585-09 SHORT-CIRCUIT CURRENT (A) 80 10K 100K FREQUENCY (Hz) JUNCTION TEMPERATURE (°C) Figure 7. Short-Circuit Current vs. Temperature Figure 8. Ripple Rejection vs. Frequency 15 10 65-1585-11 POWER (W) 20 5 0 50 60 70 80 90 100 110 120 130 140 150 CASE TEMPERATURE (°C) Figure 9. Maximum Power Dissipation REV. 1.1.2 5 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 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+. D1 1N4002 (OPTIONAL) RC1585 VIN + C1 10µF IN OUT + R1 ADJ VOUT C2 22µF + CADJ R2 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 <300mΩ. 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, larger values of output capacitors provide equally good results. D1 1N4002 (OPTIONAL) RC1585-1.5 VIN C1 10µF IN + OUT GND + VOUT C2 22µF 65-1585-12 Figure 10. Optional Protection Protection Diodes Ripple Rejection 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. 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. 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. 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. 6 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. 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. REV. 1.1.2 PRODUCT SPECIFICATION RC1585 RC1585 VIN OUT IN + C1 10µF ADJ + VREF IADJ 35µA R1 RC1585 VOUT C2 22µF VIN IN OUT ADJ R1* R2 VOUT = VREF (1 + R2/R1) + IADJ (R2) RL 65-1585-13 Figure 11. Basic Regulator Circuit * CONNECT R1 TO CASE CONNECT R2 TO LOAD 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. RC1585-1.5 IN R2* 65-1585-15 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. VIN RP PARASITIC LINE RESISTANCE RP PARASITIC LINE RESISTANCE OUT GND RL 65-1585-14 Figure 13. Connection for Best Load Regulation 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-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 RC1585T to generate 5A @ 1.5V ± 2% from a 3.3V source (3.2V to 3.6V). Assumptions: 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. • • • • • VIN = 3.6V worst case VOUT = 1.46V worst case IOUT = 5A continuous TA = 60°C θCase-to-Ambient = 3°C/W (assuming both a heatsink and a thermally conductive material) The power dissipation in this application is: If R1 connects to the load, then the effective resistance between the regulator and the load would be: PD = (VIN – VOUT) * (IOUT) = (3.6 – 1.46) * (5) = 10.7W RP x (1 + R2/R1), RP = Parasitic Line Resistance From the specification table: 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. TJ = TA + (PD) * (θCase-to-Ambient + θJC) = 60 + (10.7) * (3 + 3) = 120°C REV. 1.1.2 The junction temperature is below the maximum rating. 7 RC1585 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 RC1585 series are directly connected to the output of the device. U1 RC1585 VIN 3.3V VIN C1 10µF VOUT 1.5V VOUT + R1 124Ω ADJ + + C3 100µF R2 24.9Ω C2 100µF 65-1586-16 Figure 14. Application Circuit (RC1585) Table 1. Bill of Materials for Application Circuit for the RC1585 Item Quantity Manufacturer Part Number C1 1 Xicon L10V10 10µF, 10V Aluminum C2, C3 2 Xicon L10V100 100µF, 10V Aluminum R1 1 Generic 124Ω, 1% R2 1 Generic 24.9Ω, 1% U1 1 Fairchild RC1585T U1 RC1585-1.5 VIN 3.3V VIN C1 10µF + Description VOUT 1.5V VOUT GND + 5A Regulator C3 100µF 65-1585-17 Figure 15. Application Circuit (RC1585-1.5) Table 2. Bill of Materials for Application Circuit for the RC1585-1.5 Item Quantity Manufacturer Part Number C1 1 Xicon L10V10 10µF, 10V Aluminum C3 1 Xicon L10V100 100µF, 10V Aluminum U1 1 Fairchild RC1585T-1.5 8 Description 5A Regulator REV. 1.1.2 PRODUCT SPECIFICATION RC1585 Mechanical Dimensions 3-Lead TO-263 Package Symbol Inches Millimeters Notes Min. Max. Min. Max. A b b2 c2 D E e .160 .020 .190 .036 4.06 0.51 4.83 0.91 L L1 L2 R α .575 .090 — .017 0° .049 .051 .045 .055 .340 .380 .380 .405 .100 BSC .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° 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-. 15.88 2.79 1.40 0.78 8° E @PKG/ @HEATSINK L2 c2 D E-PIN L R (2 PLCS) b2 L1 b e -B- -A- A -C- REV. 1.1.2 9 RC1585 PRODUCT SPECIFICATION Mechanical Dimensions (continued) 3-Lead TO-263 Center Cut Package Symbol Inches Millimeters Notes Min. Max. Min. Max. A b b2 c2 D E e .160 .020 .190 .036 4.06 0.51 4.83 0.91 L L1 L2 .575 .090 — .050 .017 0° .049 .051 .045 .055 .340 .380 .380 .405 .100 BSC L3 R α .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° 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-. 15.88 2.79 1.40 1.78 0.78 8° E @PKG/ @HEATSINK L2 c2 D E-PIN L R (2 PLCS) b2 L1 L3 b e -B- -A- A -C- 10 REV. 1.1.2 PRODUCT SPECIFICATION RC1585 Mechanical Dimensions (continued) 3-Lead TO-220 Package Inches Symbol Min. A b b1 c1 øP D E e Millimeters Max. Min. .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 .100 .135 3° 7° e1 e3 F H1 J1 L L1 Q α Notes 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 Q L e3 b1 e e1 E b L1 E-PIN øP α (5X) c1 A J1 D REV. 1.1.2 F 11 RC1585 PRODUCT SPECIFICATION Mechanical Dimensions (continued) 3-Lead TO-252 Package Symbol Inches Min. A b b2 c2 D E e L Max. .086 .094 .025 .035 .030 .045 .018 .023 .210 .231 .250 .265 .090 BSC .370 .410 .020 — .055 .080 .018 .023 0° 8° L1 L2 R α Millimeters Min. Max. 2.19 2.38 0.64 0.88 0.76 1.14 0.46 0.58 5.33 5.88 6.35 6.73 2.285 BSC 9.40 10.42 0.51 — 1.40 2.03 0.46 0.58 0° 8° E @PKG/ @HEATSINK Notes: Notes 1. Dimensions are exclusive of mold flash and metal burrs. 2. Stand off-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. Dimension exclusive of dambar protrusion or intrusion. 5. Formed leads to be planar with respect to one another at seating place -C-. L2 c2 D E-PIN L R (2 PLCS) b2 L1 b e -B- -A- A -C- 12 REV. 1.1.2 RC1585 PRODUCT SPECIFICATION Ordering Information Product Number Package RC1585M TO-263 RC1585MC TO-263 Center Cut RC1585T TO-220 RC1585D TO-252 RC1585M-1.5 TO-263 RC1585MC-1.5 TO-263 Center Cut RC1585T-1.5 TO-220 RC1585D-1.5 TO-252 DISCLAIMER FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. FAIRCHILD DOES NOT ASSUME ANY LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN; NEITHER DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS. 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, or (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 significant injury to the user. 2. A critical component is 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 002Stock#DS30001585 2000 Fairchild Semiconductor Corporation