TECHNICAL DATA 2.7 A Low Dropout Positive Regulator IK1589 Description The IK1589 is a low dropout three-terminal regulator with 2.7A output current capability. This device has been optimized for VTT bus termination, where transient response and minimum input voltage are critical. The IK1589 offers fixed 1.2V with 2.7A current capability for a GTL+ bus VTT termination. 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 IK1589 is available in the industry-standard TO-220, TO-263-3L, TO-263-2L and TO-252 (DPAK) power packages. Features • • • • Output Current : 2.7 A Maximum Input Voltage : 7V Current Limiting and Thermal Protection Standard TO-220, TO-263, TO-252 (DPAK) power packages Ordering Information IK1589KB TO-220 Tube IK1589DOT TO-252 T&R IK1589D2 TO-263 Tube IK1589D2T TO-263 T&R Applications • • • A GTL + bus supply VRM 8.5 Low voltage logic supply Post regulator switching supply Absolute Maximum Ratings (note1) Parameter Min. Max. Unit 7 V 0 155 °C -65 150 °C 300 °C V IN Operating Junction Temperature Range Storage Temperature Range Lead Temperature (Soldering, 10 sec.) Power Dissipation (Note2) Internally Limited Operating Ratings Juncton Temperature Range (Note3) -10°C to 125°C Rev. 01 IK1589 Electrical Characteristics Typical and limits appearing in normal type apply Tj=+25°C Symbol Vout ∆Vout ∆Vout ∆V Ilimit Io(min) Parameter Output voltage (Note 6) Line Regulation (Note 7) Load Regulation (Note 7) Dropout Voltage (Note 8) Current Limit Minimum Load Current RR Ripple Rejection S Temperature Stability Conditions 3.3V ≤ Vin ≤ 7V Min (Note5) Typ (Note4) Max (Note5) Units 1.176 1.200 1.224 V 0.2 % 1.5 % 1.3 V (Vout + 1.5V) ≤ Vin ≤ 7V Iout = 10 mA (Vin – Vout) = 3V 10mA ≤ Iout ≤ 2.7A ∆Vref=1%, Iout = 2.7A - (Vin-Vout) = 2V 4.5 1.5V ≤ (Vin-Vout) ≤ 5.75V f RIPLE = 120HZ, COUT=25µF Tantalum, Iout=5A;V I N =Vout+2V A 10 mA 60 - - dB - 0.5 - % NOTES 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Rating indicate conditions for which the device is intended to be functional, but specific performance is not guaranteed. For guaranteed specifications and the test conditions, see the Electrical Characteristics. NOTES 2: Power Dissipation is kept in a safe range by current limiting circuitry. NOTES 3: The maximum power dissipation is a function of Tj (MAX), ΘjA and T A . The maximum allowable power dissipation at any ambient temperature is PD=(Tj(MAX) – T A)ΘjA. NOTES 4: Typical Values represent the most likely parametric norm NOTES 5: All limits are guaranteed by testing or statistical analysis NOTES 6: IFULL LOAD is defind in the current limit curves . The IFULL LOAD curve defines the current limit as a function of input-to-output voltage . NOTES 7: Load and Line regulation are measured at constant junction temperature , and are guaranteed up to the maximum power dissipation of 30W.Power dissipation is determined by the input/output differential and the output current. Guaranteed maximum power dissipation will not be available over the full input/output range. NOTES 8: Dropout voltage is specified over the full output current range of the device. Typical Application Rev. 01 IK1589 Typical Performance Characteristics Figure 1. Figure 2. Figure 3. Figure 4. Figure 5. Figure 6. Rev. 01 IK1589 Applications Information General The IK1589 is a three-terminal regulator optimized for a GTL+ VTT termination applications. It is short-circuit protected, and offers thermal shutdown to turn off the regulator when the junction temperature exceeds about 150°C. The IK1589 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 a GTL+. Stability The IK1589 requires an output capacitor as a part of the frequency compensation. It is recommended to use a 22µF solid tantalum or a 100µF 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. Protection Diodes In normal operation, the IK1589 does not require any protection diodes. A protection diode between the input and output pins is usually not needed. An internal diode between the input and output pins on the IK1589 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 1000 µF to 5000 µF, 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 7. Usually, normal power supply cycling or system “hot plugging and unplugging” will not generate current large enough to do any damage. 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. Figure 7. Optional Protection Load Regulation It is not possible to provide true remote load sensing because the IK1589 is a three-terminal device. 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 8. Rev. 01 IK1589 Figure 8. Connection for Best Load Regulation Thermal Considerations The IK1589 protects itself 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 IK1589 to generate 2.7A @ 1.2V ±2% from a 3.3V source (3.2V to 3.6V). Assumptions: • VIN= 3.6V worst case • VOUT = 1.176V worst case • IOUT = 2.7A continuous • TA = 70°C • θCase-to-Ambient = 3°C/W (assuming both a heatsink and a thermally conductive material) The power dissipation in this application is: PD = (VIN – VOUT) * (IOUT) = (3.6 – 1.18) * (2.7) = 6.53W From the specification table: TJ = TA + (PD) * (θCase-to-Ambient + θJC)= 70 + (6.53) * (3 + 3) = 109°C The junction temperature is below the maximum rating. 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 case of the IK1589 is directly connected to the output of the device. Figure 9. Application Circuit (IK1589) Rev. 01 IK1589 Rev. 01 IK1589 Rev. 01 IK1589 Rev. 01 IK1589 TO-263-2L PACKAGE OUTLINE DIMENSION Rev. 01