T1587

T1587_15 LINER

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7A, 4.6A, 3A Low Dropout Fast Response Positive Regulators Adjustable and Fixed NOTE: MICROPROCESSOR APPLICATIONS WITH LOAD TRANSIENTS OF 3.8A REQUIRE OUTPUT DECOUPLING CAPACITANCE > 1300µF ON FIXED VOLTAGE PARTS TO ACHIEVE < 50mV OF DEVIATION FROM NOMINAL OUTPUT. CONSULT FACTORY FOR DETAILS The LT 1584/LT1585/LT1587 are low dropout three- terminal regulators with 7A, 4.6A and 3A output current capability, respectively. Design has been optimized for low voltage applications where transient response and mini- mum input voltage are critical. Similar to the LT1083/4/5 family, it has lower dropout voltage and faster transient response. These improvements make it ideal for low volt- age microprocessor applications requiring a regulated 2.5V to 3.6V output with an input supply below 7V. Current limit is trimmed to ensure specified output current and controlled short-circuit current. On-chip thermal lim- iting provides protection against any combination of over- load that would create excessive junction temperatures. The LT1585/LT1587 are available in both the through-hole and surface mount versions of the industry standard 3-pin TO-220 power package. The LT1584 is available in the through-hole 3-pin TO-220 power package. n Fast Transient Response n Guaranteed Dropout Voltage at Multiple Currents n Load Regulation: 0.05% Typical n Trimmed Current Limit n On-Chip Thermal Limiting n Standard 3-Pin Power Package n Pentium TM Processor Supplies n PowerPC TM Supplies n Other 2.5V to 3.6V Microprocessor Supplies n Low Voltage Logic Supplies n Battery-Powered Circuitry n Post Regulator for Switching Supply LT1585/7CM, LT1584/5/7CT Adjustable LT1585/7CM-3.3, LT1584/5/7CT-3.3 3.3V Fixed LT1585CM-3.38, LT1584/5CT-3.38 3.38V Fixed LT1585/7CM-3.45, LT1584/5/7CT-3.45 3.45V Fixed LT1585/7CM-3.6, LT1584/5/7CT-3.6 3.6V Fixed , LTC and LT are registered trademarks of Linear Technology Corporation. Pentium is a trademark of Intel Corporation. PowerPC is a trademark of IBM Corporation. 3.3V, 7A, 4.6A, 3A Regulator LT1584-3.3 LT1585-3.3 LT1587-3.3 V IN ‡ 4.75V

1585 TA01

• REQUIRED FOR STABILITY LT1584: C2 = 22mF, LT1585/LT1587: C2 = 10mF 3.3V 7A, 4.6A, 3A C2* SOLID TANTALUM OUTPUT CURRENT (A) INPUT/OUTPUT DIFFERENTIAL (V) 1.5 1.4 1.3 1.2 1.1 1.0 0.9 0.8 0.7 0.6 0.5

1585 TA02

Dropout Voltage vs Output Current

ABSOLUTE AXI U RATI GSW WW U (Note 1) Operating Junction Temperature Range C-Grade I-Grade 100% Thermal Limit Functional Test PRECONDITIONI GU U U ORDER PART NUMBER ORDER PART NUMBER θJA = 30°C/W* θJA = 50°C/W θJA = 30°C/W* θJA = 50°C/W LT1584CT-3.3 LT1584IT-3.3 LT1585CT-3.3 LT1587CT-3.3 LT1584CT-3.38 LT1585CT-3.38 LT1584CT-3.45 LT1585CT-3.45 LT1587CT-3.45 LT1584CT-3.6 LT1585CT-3.6 LT1587CT-3.6 * 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 >4 0°C/W with other mounting techniques. LT1585CM-3.3 LT1585CM-3.38 LT1585CM-3.45 LT1585CM-3.6 LT1587CM-3.3 LT1587CM-3.45 LT1587CM-3.6 LT1585CM LT1587CM LT1584CT LT1585CT LT1587CT PACKAGE/ORDER INFORMATIONW UU M PACKAGE 3-LEAD PLASTIC DD FRONT VIEW VIN VOUT GND TAB IS OUTPUT T PACKAGE 3-LEAD PLASTIC TO-220 VIN VOUT GND FRONT VIEW TAB IS OUTPUT Consult LTC Marketing for parts specified with wider operating temperature ranges.

PARAMETER CONDITIONS MIN TYP MAX UNITS Reference Voltage LT1584 1.5V ≤ (VIN – VOUT) ≤ 3V, 10mA ≤ IOUT ≤ 7A LT1585 1.5V ≤ (VIN – VOUT) ≤ 5.75V, 10mA ≤ IOUT ≤ 4.6A, TJ ≥ 25°C 1.5V ≤ (VIN – VOUT) ≤ 5.75V, 10mA ≤ IOUT ≤ 4A, TJ < 25°C Output Voltage LT1584-3.3 4.75V ≤ VIN ≤ 6.3V, 0mA ≤ IOUT ≤ 7A LT1585-3.3 4.75V ≤ VIN ≤ 7V, 0mA ≤ IOUT ≤ 4.6A, TJ ≥ 25°C 4.75V ≤ VIN ≤ 7V, 0mA ≤ IOUT ≤ 4A, TJ < 25°C LT1584-3.38 4.75V ≤ VIN ≤ 6.38V, 0mA ≤ IOUT ≤ 7A LT1584-3.45 4.75V ≤ VIN ≤ 6.45V, 0mA ≤ IOUT ≤ 7A LT1585-3.45 4.75V ≤ VIN ≤ 7V, 0mA ≤ IOUT ≤ 4A Line Regulation LT1584/5/7 2.75V ≤ VIN ≤ 7V, IOUT = 10mA (Notes 2, 3) LT1584/5/7-3.3 4.75V ≤ VIN ≤ 7V, IOUT = 0mA LT1584/5-3.38 4.75V ≤ VIN ≤ 7V, IOUT = 0mA LT1584/5/7-3.45 4.75V ≤ VIN ≤ 7V, IOUT = 0mA LT1584/5/7-3.6 4.75V ≤ VIN ≤ 7V, IOUT = 0mA l 0.005 0.2 % Load Regulation LT1584/5/7 (V N – VOUT) = 3V, TJ = 25°C, 10mA ≤ IOUT ≤ IFULL LOAD (Notes 2, 3, 4) LT1584/5/7-3.3 V IN = 5V, TJ = 25°C, 0mA ≤ IOUT ≤ IFULL LOAD LT1584/5-3.38 V IN = 5V, TJ = 25°C, 0mA ≤ IOUT ≤ IFULL LOAD LT1584/5/7-3.45 V IN = 5V, TJ = 25°C, 0mA ≤ IOUT ≤ IFULL LOAD LT1584/5/7-3.6 V IN = 5.25V, TJ = 25°C, 0mA ≤ IOUT ≤ IFULL LOAD 0.05 0.3 % l 0.05 0.5 % Dropout Voltage LT1585/7 ΔVREF = 1%, IOUT = 3A LT1585/7-3.3 ΔVOUT = 1%, IOUT = 3A LT1585-3.38 ΔVOUT = 1%, IOUT = 3A LT1585/7-3.45 ΔVOUT = 1%, IOUT = 3A LT1585/7-3.6 ΔVOUT = 1%, IOUT = 3A l 1.150 1.300 V LT1585 ΔVREF = 1%, IOUT = 4.6A, TJ ≥ 25°C ΔVREF = 1%, IOUT = 4A, TJ < 25°C LT1585-3.3 ΔVOUT = 1%, IOUT = 4.6A, TJ ≥ 25°C ΔVOUT = 1%, IOUT = 4A, TJ < 25°C LT1585-3.38 ΔVOUT = 1%, IOUT = 4A LT1585-3.45 ΔVOUT = 1%, IOUT = 4A LT1585-3.6 ΔVOUT = 1%, IOUT = 4A l 1.200 1.400 V LT1584 ΔVREF = 1%, IOUT = 6A LT1584-3.3 ΔVOUT = 1%, IOUT = 6A LT1584-3.38 ΔVOUT = 1%, IOUT = 6A LT1584-3.45 ΔVOUT = 1%, IOUT = 6A LT1584-3.6 ΔVOUT = 1%, IOUT = 6A TJ ≥ 25°C l 1.200 1.300 V TJ < 25°C l 1.200 1.350 V LT1584IT-3.3 T J < 25°C l 1.200 1.450 V ELECTRICAL CHARACTERISTICSThe l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C.

ELECTRICAL CHARACTERISTICSThe l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. PARAMETER CONDITIONS MIN TYP MAX UNITS Dropout Voltage LT1584 ΔVREF = 1%, IOUT = 7A LT1584-3.3 ΔVOUT = 1%, IOUT = 7A LT1584-3.38 ΔVOUT = 1%, IOUT = 7A LT1584-3.45 ΔVOUT = 1%, IOUT = 7A LT1584-3.6 ΔVOUT = 1%, IOUT = 7A l 1.250 1.400 V LT1584IT-3.3 T J < 25°C l 1.250 1.500 V Current Limit LT1584 (V IN – VOUT) = 3V (Note 4) LT1584-3.3 (V IN – VOUT) = 3V LT1584-3.38 (V IN – VOUT) = 3V LT1584-3.45 (V IN – VOUT) = 3V LT1584-3.6 (V IN – VOUT) = 3V l 7.100 8.250 A LT1585 (V IN – VOUT) = 5.5V LT1585-3.3 (V IN – VOUT) = 5.5V TJ ≥ 25°C l 4.600 5.25 A TJ < 25°C l 4.100 5.25 A LT1585-3.38 (V IN – VOUT) = 5.5V LT1585-3.45 (V IN – VOUT) = 5.5V LT1585-3.6 (V IN – VOUT) = 5.5V l 4.100 4.750 A LT1587 (V IN – VOUT) = 5.5V LT1587-3.3 (V IN – VOUT) = 5.5V LT1587-3.45 (V IN – VOUT) = 5.5V LT1587-3.6 (V IN – VOUT) = 5.5V l 3.100 3.750 A Adjust Pin Current LT1584/5/7 l 55 120 µA Adjust Pin Current LT1584 1.5V ≤ (VIN – VOUT) ≤ 3V, 10mA ≤ IOUT ≤ IFULL LOAD Change (Note 4) LT1585/7 1.5V ≤ (VIN – VOUT) ≤ 5.75V, 10mA ≤ IOUT ≤ IFULL LOAD l 0.2 5 µA Minimum LT1584/5/7 1.5V ≤ (VIN – VOUT) ≤ 5.75V l 21 0m A Load Current Quiescent Current LT1584/5/7-3.3 V IN = 5V LT1584/5-3.38 V IN = 5V LT1584/5/7-3.45 V IN = 5V LT1584/5/7-3.6 V IN = 5V l 81 3m A LT1584IT-3.3 V IN = 5V l 81 5m A Ripple Rejection LT1584 f = 120Hz, COUT = 25µF Tant., (VIN – VOUT) = 2.5V, IOUT = 7A LT1584-3.3 f = 120Hz, COUT = 25µF Tant., VIN = 5.8V, IOUT = 7A LT1584-3.38 f = 120Hz, COUT = 25µF Tant., VIN = 5.88V, IOUT = 7A LT1584-3.45 f = 120Hz, COUT = 25µF Tant., VIN = 5.95V, IOUT = 7A LT1584-3.6 f = 120Hz, COUT = 25µF Tant., VIN = 6.1V, IOUT = 7A LT1585 f = 120Hz, COUT = 25µF Tant., (VIN – VOUT) = 3V, IOUT = 4.6A, TJ ≥ 25°C f = 120Hz, COUT = 25µF Tant., (VIN – VOUT) = 3V, IOUT = 4A, TJ < 25°C LT1585-3.3 f = 120Hz, C OUT = 25µF Tant., VIN = 6.3V, IOUT = 4.6A, TJ ≥ 25°C f = 120Hz, COUT = 25µF Tant., VIN = 6.3V, IOUT = 4A, TJ < 25°C LT1585-3.38 f = 120Hz, C OUT = 25µF Tant., VIN = 6.38V, IOUT = 4A LT1585-3.45 f = 120Hz, C OUT = 25µF Tant., VIN = 6.45V, IOUT = 4A LT1585-3.6 f = 120Hz, C OUT = 25µF Tant., VIN = 6.6V, IOUT = 4A LT1587 f = 120Hz, C OUT = 25µF Tant., (VIN – VOUT) = 3V, IOUT = 3A LT1587-3.3 f = 120Hz, C OUT = 25µF Tant., VIN = 6.3V, IOUT = 3A LT1587-3.45 f = 120Hz, C OUT = 25µF Tant., VIN = 6.45V, IOUT = 3A LT1587-3.6 f = 120Hz, C OUT = 25µF Tant., VIN = 6.6V, IOUT = 3A l 60 72 dB

ELECTRICAL CHARACTERISTICSThe l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. PARAMETER CONDITIONS MIN TYP MAX UNITS Thermal Regulation LT1584/5/7 T A = 25°C, 30ms pulse LT1584/5/7-3.3 T A = 25°C, 30ms pulse LT1584/5-3.38 T A = 25°C, 30ms pulse LT1584/5/7-3.45 T A = 25°C, 30ms pulse LT1584/5/7-3.6 T A = 25°C, 30ms pulse 0.004 0.02 %/W Temperature Stability l 0.5 % Long-Term Stability T A = 125°C, 1000 Hrs. 0.03 1.0 % RMS Output Noise T A = 25°C, 10Hz ≤ f ≤ 10kHz 0.003 % (% of VOUT) Thermal Resistance LT1584 T Package: Control Circuitry/Power Transistor 0.65/2.7 °C/W Junction to Case LT1585 T Package: Control Circuitry/Power Transistor 0.7/3.0 °C/W maximum output power will not be available over the full input/output voltage range. Note 4: IFULL LOAD is defined as the maximum value of output load current as a function of input-to-output voltage. IFULL LOAD is equal to 7A for the LT1584, 4.6A at TJ ≥ 25°C and 4A at TJ < 25°C for the LT1585/LT1585-3.3 and 3A for the LT1587. The remaining LT1585 fixed voltage versions are 4A. The LT1585 and LT1587 have constant current limit with changes in input-to-output voltage. The LT1584 has variable current limit which decreases about 4A as input-to-output voltage increases from 3V to 7V. Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: 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. Note 3: Line and load regulation are guaranteed up to the maximum power dissipation (25W for the LT1584 in T package, 26.5W for the LT1585 in T package, 18W for the LT1587 in T package). Power dissipation is determined by input/output differential and the output current. Guaranteed

TYPICAL PERFORMANCE CHARACTERISTICS UW LT1584 Dropout Voltage vs Output Current TEMPERATURE (°C) –0.20 OUTPUT VOLTAGE DEVIATION (%) –0.10 0.10 –0.15 –0.05 0.05 –25 25 75 125 LT1584 • TPC03 175–50–75 0 50 100 150 ΔI = 7A LT1584 Load Regulation vs Temperature INPUT/OUTPUT DIFFERENTIAL (V) SHORT-CIRCUIT CURRENT (A) 2 4 5 LT1584 • TPC02 1 3 6 7 T = 125°C T = 25°C T = –5 °C MINIMUM LT1584 Short-Circuit Current vs Input/Output Differential LT1585 Dropout Voltage vs Output Current LT1585 Load Regulation vs Temperature LT1585 Short-Circuit Current vs Temperature TEMPERATURE (°C) –75 SHORT-CIRCUIT CURRENT (A) 5.0 5.5 125 LT1584 • TPC05 4.5 4.0 –25 25 50 175 6.0 75–50 0 150100 TEMPERATURE (°C) –0.20 OUTPUT VOLTAGE DEVIATION (%) –0.10 0.10 –0.15 –0.05 0.05 –25 25 75 125 LT1584 • TPC03 175–50–75 0 50 100 150 ΔI = 4.6A LT1587 Dropout Voltage vs Output Current LT1587 Load Regulation vs Temperature LT1587 Short-Circuit Current vs Temperature TEMPERATURE (°C) –75 SHORT-CIRCUIT CURRENT (A) 4.0 4.5 125 LT1584 • TPC05 3.5 3.0 –25 25 50 175 5.0 75–50 0 150100 TEMPERATURE (°C) –0.20 OUTPUT VOLTAGE DEVIATION (%) –0.10 0.10 –0.15 –0.05 0.05 –25 25 75 125 LT1584 • TPC09 175–50–75 0 50 100 150 ΔI = 3A OUTPUT CURRENT (A) 0.5 DROPOUT VOLTAGE (V) 0.6 0.8 0.9 1.0 1.5 1.2 2 4 5 LTC1584 • TPC01 0.7 1.3 1.4 1.1 1 3 6 7 T = –5 °C T = 125°C T = 25°C GUARANTEED TEST POINTS OUTPUT CURRENT (A) DROPOUT VOLTAGE (V) 1.1 1.3 1.5 LT1585 • TPC04 0.9 0.7 1.0 1.2 1.4 0.8 0.6 0.5 1 2 3 5 T = –5 °C T = 125°C T = 25°C GUARANTEED TEST POINTS OUTPUT CURRENT (A) 0.5 DROPOUT VOLTAGE (V) 0.7 0.8 0.9 1.0 1.1 1.2 0.5 1.0 1.5 2.0 LT1584 • TPC07 2.5 1.3 1.4 1.5 0.6 3.0 T = –5 °C T = 125°C T = 25°C GUARANTEED TEST POINTS

TYPICAL PERFORMANCE CHARACTERISTICS UW LT1584/5/7 Minimum Load Current vs Temperature LT1584/5/7-3.XX Quiescent Current vs Temperature LT1584/5/7 Adjust Pin Current vs Temperature LT1584/5/7 Ripple Rejection vs Frequency LT1584 Maximum Power Dissipation* LT1585/7 Maximum Power Dissipation* LT1584/5/7 Reference Voltage vs Temperature Output Voltage vs Temperature Using Adjustable LT1584/5/7 TEMPERATURE (°C) –75 REFERENCE VOLTAGE (V) 1.255 1.265 1.275 125 LT1584 • TPC10 1.245 1.235 1.250 1.260 1.270 1.240 1.230 1.255 –25 25 75–50 150 0 50 100 175 TEMPERATURE (°C) –75 OUTPUT VOLTAGE (V) 3.60 3.65 3.70 125 LT1584 • TPC11 3.55 3.50 3.45 3.40 3.35 3.30 3.25 3.20 –25 25 75–50 150 0 50 100 175 VOUT = 3.6V VOUT = 3.45V VOUT = 3.38V VOUT = 3.3V VOUT SET WITH 1% RESISTORS TEMPERATURE (°C) –75 OUTPUT VOLTAGE (V) 3.60 3.65 3.70 125 LT1584 • TPC12 3.55 3.50 3.45 3.40 3.35 3.30 3.25 3.20 –25 25 75–50 150 0 50 100 175 VOUT = 3.6V VOUT = 3.45V VOUT = 3.38V VOUT = 3.3V TEMPERATURE (°C) –75 MINIMUM LOAD CURRENT (mA) 125 LT1584 • TPC13 –25 25 75–50 150 0 50 100 175 TEMPERATURE (°C) –75 ADJUST PIN CURRENT (µA) 100 125 LT1584 • TPC14 –25 25 75–50 150 0 50 100 175 TEMPERATURE (°C) –75 QUIESCENT CURRENT (mA) 125 LT1584 • TPC15 –25 25 75–50 150 0 50 100 175 FREQUENCY (Hz) RIPPLE REJECTION (dB) 10 1k 10k 100k LT1584 • TPC16 100 LT1584: (VIN – VOUT) ≤ 2.5V LT1585/87: (VIN – VOUT) ≤ 3V 0.5V ≤ VRIPPLE ≤ 2V IOUT = IFULL LOAD CASE TEMPERATURE (˚C) POWER (W) 80 100 LT1584 • TPC17 60 70 90 110 120 130 140 150 LT1585 LT1587 CASE TEMPERATURE (°C) POWER (W) 70 90 110 130 LT1584 • TPC18 1506050 80 100 120 140 LT1584/5/7-3.XX Output Voltage vs Temperature *AS LIMITED BY MAXIMUM JUNCTION TEMPERATURE *AS LIMITED BY MAXIMUM JUNCTION TEMPERATURE

LT1584 • BD ADJ SI PLIFIED SCHE ATICWW

APPLICATIONS INFORMATIONWU UU General The LT1584/LT1585/LT1587 family of three-terminal regulators is easy to use and has all the protection features expected in high performance linear regulators. The de- vices are short-circuit protected, safe-area protected, and provide thermal shutdown to turn off the regulators should the junction temperature exceed about 150°C. The LT1584/LT1585/LT1587 family includes adjustable and fixed voltage versions. These ICs are pin compatible with the LT1083/LT1084/ LT1085 family of linear regulators but offer lower dropout voltage and faster transient response. The trade-off for this improved performance is a 7V maximum supply voltage. Similar to the LT1083/LT1084/LT1085 family, the LT1584/ LT1585/LT1587 regulators require an output capacitor for stability. However, the improved frequency compensation permits the use of capacitors with much lower ESR while still maintaining stability. This is critical in addressing the needs of modern, low voltage, high speed microprocessors. Current generation microprocessors cycle load current from almost zero to amps in tens of nanoseconds. Output voltage tolerances are tighter and include transient re- sponse as part of the specification. The LT1584/LT1585/ LT1587 family is specifically designed to meet the fast current load-step requirements of these microprocessors and saves total cost by needing less output capacitance in order to maintain regulation. Stability The circuit design in the LT1584/LT1585/LT1587 family requires the use of an output capacitor as part of the frequency compensation. For all operating conditions, the addition of a 22 µF solid tantalum or a 100 µF aluminum electrolytic on the output ensures stability. Normally, the LT1584/LT1585/LT1587 can use smaller value capacitors. Many different types of capacitors are available and have widely varying characteristics. These capacitors differ in capacitor tolerance (sometimes ranging up to ±100%), equivalent series resistance, equivalent series inductance, and capacitance temperature coefficient. The LT1584/ LT1585/LT1587 frequency compensation optimizes fre- quency response with low ESR capacitors. In general, use capacitors with an ESR of less than 1Ω . On the adjustable LT1584/LT1585/LT1587, bypassing the adjust terminal improves ripple rejection and transient response. Bypassing the adjust pin increases the required output capacitor value. The value of 22 µF tantalum or 100µF aluminum covers all cases of bypassing the adjust terminal. With no adjust pin bypassing, smaller values of capacitors provide equally good results. Normally, capacitor values on the order of several hundred microfarads are used on the output of the regulators to ensure good transient response with heavy load current changes. Output capacitance can increase without limit and larger values of output capacitance further improve the stability and transient response of the LT1584/LT1585/ LT1587 family. Large load current changes are exactly the situation pre- sented by modern microprocessors. The load current step contains higher order frequency components that the output decoupling network must handle until the regulator throttles to the load current level. Capacitors are not ideal elements and contain parasitic resistance and inductance. These parasitic elements dominate the change in output voltage at the beginning of a transient load step change. The ESR of the output capacitors produces an instanta- neous step in output voltage (ΔV = ΔI × ESR). The ESL of the output capacitors produces a droop proportional to the rate of change of output current (V = L × ΔI/Δt). The output capacitance produces a change in output voltage propor- tional to the time until the regulator can respond (ΔV = Δt × ΔI/C). These transient effects are illustrated in Figure 1. Figure 1 ESR EFFECTS LT1584 • F01 ESL EFFECTS CAPACITANCE EFFECTS POINT AT WHICH REGULATOR TAKES CONTROL SLOPE, = V t ΔI C

APPLICATIONS INFORMATIONWU UU The use of capacitors with low ESR, low ESL, and good high frequency characteristics is critical in meeting the output voltage tolerances of these high speed microprocessors. These requirements dictate a combination of high quality, surface mount tantalum capacitors and ceramic capaci- tors. The location of the decoupling network is critical to transient response performance. Place the decoupling network as close as possible to the processor pins because trace runs from the decoupling capacitors to the processor pins are inductive. The ideal location for the decoupling network is actually inside the microprocessor socket cav- ity. In addition, use large power and ground plane areas to minimize distribution drops. A possible stability problem that occurs in monolithic linear regulators is current limit oscillations. The LT1585/LT1587 essentially have a flat current limit over the range of input supply voltage. The lower current limit rating and 7V maximum supply voltage rating for these devices permit this characteristic. Current limit oscillations are typically nonexistent, unless the input and output decoupling ca- pacitors for the regulators are mounted several inches from the terminals. The LT1584 differs from the LT1585/ LT1587 and provides current limit foldback as input-to- output differential voltage increases. This safe-area char- acteristic exhibits a negative impedance because increas- ing voltage causes output current to decrease. Negative resistance during current limit is not unique to the LT1584 devices and is present on many power IC regulators. The value of the negative resistance is a function of how fast the current limit is folded back as input-to-output voltage increases. This negative resistance can react with capaci- tors and inductors on the input and output to cause oscillation during current limit. Depending on the values of series resistances, the overall system may end up unstable. However, the oscillation causes no problem and the IC remains protected. In general, if this problem occurs and is unacceptable, increasing the amount of output capacitance helps dampen the system. Protection Diodes In normal operation, the LT1584/LT1585/LT1587 family does not require any protection diodes. Older three-termi- nal regulators require protection diodes between the out- put pin and the input pin or between the adjust pin and the output pin to prevent die overstress. On the adjustable LT1584/LT1585/LT1587, internal resis- tors limit internal current paths on the adjust pin. There- fore, 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 output pins on the LT1584/LT1585/LT1587 family 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 of the LT1584/LT1585/LT1587 can generate those levels of current, and a diode from output to input is then recom- mended. This is shown in Figure 2. 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-to- output voltage differential causes the internal transistors to break down and none of the protection circuitry is then functional. Figure 2 LT1584-3.3 1N4002 (OPTIONAL) GND VIN VOUTIN OUT 10mF 22mF LT1584 1N4002 (OPTIONAL) ADJ VIN VOUTIN OUT LT1584 • F02 10mF 22mFR1 R2CADJ + +

sink interface resistance, and the heat sink resistance. IC junction to the bottom of the case directly below the die. Figure 5. Connection for Best Load Regulation

APPLICATIONS INFORMATIONWU UU TYPICAL APPLICATIONS N U LT1587-3.45 GND IN PLACE AT MICROPROCESSOR SOCKET VCC PINS 10mF 10V OUTVIN ‡ 4.75V 22mF 10V C3 TO C6 47mF 10V ESR OF THE 47mF IS <0.1W LT1584 • TA03 C7 TO C15 0.1mF C16 TO C24 0.01mF 3.45V +++ Recommended LT1587-3.45 Circuit for the Intel 486 TM DX4 TM Overdrive Microprocessor LT1585 Transient Response for 3.8A Load Current Step* LT1584 • TA05100µs/DIV VOUT 50mV/DIV IOUT 2A/DIV Minimum Parts Count LT1585 Adjustable Circuit for the Intel Pentium VRE Processor 486 and DX4 are trademarks of Intel Corporation. *TRANSIENT RESPONSE MEASURED WITH AN INTEL POWER VALIDATOR. VOUT IS MEASURED AT THE POWER VALIDATOR LT1585CT ADJ IN AVX CORP. (803) 448-9411 THERMALLOY INC. (214) 243-4321 DO NOT SUBSTITUTE COMPONENTS. C1 TO C3 220mF 10V AVX TPS

3 EACH

0.1% 330nF 16V AVX X7R 0805 OUT4.75V TO 5.25V THERMALLOY 7020B-MT PLACE IN MICROPROCESSOR SOCKET CAVITY C5 TO C10 100mF 10V AVX TPS

6 EACH

10 EACH

0.1% 3.50V 4.6A 1584/5/7 TA04 contribution to the total thermal resistance. Please consult “Mounting Considerations for Power Semiconductors”

1990 Linear Applications Handbook, Volume I , Pages

RR3-1 to RR3-20. The output connects to the case of all devices in the LT1584/LT1585/LT1587 series. For example, using an LT1585CT-3.3 (TO-220, commer- cial) and assuming: V IN(Max Continuous) = 5.25V (5V + 5%), VOUT = 3.3V, IOUT = 4.6A TA = 70°C, θHEAT SINK = 4°C/W θCASE-TO-HEAT SINK = 1°C/W (with Thermal Compound) Power dissipation under these conditions is equal to: PD = (VIN – VOUT)(IOUT) = (5.25 – 3.3)(4.6) = 9W Junction temperature will be equal to: TJ = TA + PD(θHEAT SINK + θCASE-TO-HEAT SINK + θJC) For the Control Section: 121.3°C < 125°C = TJMAX (Control Section Commercial range) For the Power Transistor: 142°C < 150°C = TJMAX (Power Transistor Commercial Range) In both cases the junction temperature is below the maxi- mum rating for the respective sections, ensuring reliable operation.

(Reference LTC DWG # 05-08-1460) .050 (1.270) .143 +.012 –.020 ()3.632 +0.305 –0.508 .100 (2.54) BSC .013 – .023 (0.330 – 0.584) .095 – .115 (2.413 – 2.921) .004 +.008 –.004 ()0.102 +0.203 –0.102 .050 – .012 (1.270 – 0.305) .059 (1.499) .045 – .055 (1.143 – 1.397) .165 – .180 (4.191 – 4.572) .330 – .370 (8.382 – 9.398) .060 (1.524) TYP .390 – .415 (9.906 – 10.541) 15° .300 (7.620) .075 (1.905) .183 (4.648) .060 (1.524) .060 (1.524) .256 (6.502) BOTTOM VIEW OF DD PAK HATCHED AREA IS SOLDER PLATED COPPER HEAT SINK M (DD3) 0204 .420 .350 .565 .090 .070.100 .420 .276 .325 .205 .080 .565 .090 .070.100 RECOMMENDED SOLDER PAD LAYOUT FOR THICKER SOLDER PASTE APPLICATIONS RECOMMENDED SOLDER PAD LAYOUT NOTE: 1. DIMENSIONS IN INCH/(MILLIMETER) 2. DRAWING NOT TO SCALE .320

Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights. PACKAGE I FOR ATIOU UW T Package 3-Lead Plastic TO-220 (Reference LTC DWG # 05-08-1420) .100 (2.540) BSC .028 – .038 (0.711 – 0.965) T3 (TO-220) 0801 .045 – .055 (1.143 – 1.397) .165 – .180 (4.191 – 4.572) .095 – .115 (2.413 – 2.921) .013 – .023 (0.330 – 0.584) .520 – .570 (13.208 – 14.478) .980 – 1.070 (24.892 – 27.178) .218 – .252 (5.537 – 6.401) .050 (1.270) TYP .147 – .155 (3.734 – 3.937) DIA .390 – .415 (9.906 – 10.541) .330 – .370 (8.382 – 9.398) .460 – .500 (11.684 – 12.700) .570 – .620 (14.478 – 15.748) .230 – .270 (5.842 – 6.858)

LT/TP 0404 1K REV A • PRINTED IN USA  LINEAR TECHNOLOGY CORPORATION 1 995 TYPICAL APPLICATIONS N U Guaranteed LT1584/LT1431 Circuit for the Intel 90MHz and 100MHz Pentium Processors (Meets Intel Specifications with Worst-Case Tolerances) LT1584 ADJ IN C2 TO C4 220mF 10V AVX TPS 0.01mF 0.1mF 33pF NPO 1 R3C 800W R3B 1.35k R3A 1.15k LT1431S COMP COL SGND FGND V+ REF RT RM PGND SGND LT1584 • TA06 PGND SENSE VOUT PLACE IN MICROPROCESSOR SOCKET CAVITY C14 TO C23 1mF 16V AVX Y5V 0805 NOTES: UNLESS OTHERWISE SPECIFIED 1. ALL RESISTOR VALUES ARE OHMS, 1/8W, 5% 2. ALL CAPACITORS ARE 50V, 20% 3. ALL POLARIZED CAPACITORS ARE AVX TYPE TPS OR EQUIVALENT 4. INPUT CAPACITANCE MAY BE REDUCED IF THE 5V SUPPLY IS WELL BYPASSED 5. FOR 100MHz PENTIUM PROCESSOR, INPUT VOLTAGE MUST BE AT LEAST 4.85V AT THE REGULATOR INPUT 6. FOR PENTIUM VRE PROCESSOR, R4 NOT INSTALLED – FOR 3.3V OUTPUT, INSTALL 0W JUMPER RESISTOR R4 7. R3A TO R3E ARE B.I. TECHNOLOGY 627V100 100mF 10V THERMALLOY 7021B-MT LT1584/LT1431 Transient Response for 3.8A Load Current Step* VOUT 50mV/DIV 100µs/DIV LT1584 • TA07 IOUT 2A/DIV *TRANSIENT RESPONSE MEASURED WITH AN INTEL POWER VALIDATOR. V OUT IS MEASURED AT THE POWER VALIDATOR RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1083/84/85 7.5A, 5A, 3A Low Dropout Linear Regulators Fixed Output at 3.3V, 3.6V, 5V and 12V, V IN to 25V LT1083/84/85 7.5A, 5A, 3A Low Dropout Linear Regulators Adjustable Output with up to 30V (V IN – VOUT) Differential LT1086 1.5A Low Dropout Linear Regulator Both Fixed and Adjustable Versions, (V IN – VOUT) to 30V LT1521 300mA Low Dropout Linear Regulator with 12 µA Quiescent Both Fixed and Adjustable Versions, Surface Mount Current and Shutdown Package Available LT1529 3A Low Dropout Linear Regulator with 50 µA Quiescent Both Fixed and Adjustable Versions, Surface Mount Current and Shutdown Package Available LT1580 7A Very Low Dropout Linear Regulator 540mV Dropout at 7A, Remote Sensing Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 l FAX: (408) 434-0507 l www.linear.com