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LT1585A/LT1585A-3.3 5A Low Dropout Fast Response Positive Regulators Adjustable and Fixed
FEATURES
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DESCRIPTION
The LT (R)1585A/LT1585A-3.3 are low dropout 3-terminal regulators with 5A output current capability. Design has been optimized for low voltage applications where transient response and minimum input voltage are critical. Similar to the LT1084 family, these regulators feature lower dropout voltage and faster transient response. These improvements make them ideal for low voltage 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 limiting provides protection against any combination of overload that would create excessive junction temperatures. The LT1585A/LT1585A-3.3 are available in the industry standard 3-pin TO-220 power package.
, LTC and LT are registered trademarks of Linear Technology Corporation. Pentium is a registered trademark of Intel Corporation. PowerPC is a trademark of IBM Corporation.
Fast Transient Response Guaranteed Dropout Voltage at Multiple Currents Load Regulation: 0.05% Typ Trimmed Current Limit On-Chip Thermal Limiting Standard 3-Pin Power Package
APPLICATIONS
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Pentium(R) Processor Supplies PowerPCTM Supplies Other 2.5V to 3.6V Microprocessor Supplies Low Voltage Logic Supplies Battery-Powered Circuitry Post Regulator for Switching Supply
Adjustable 3.3V Fixed
LT1585ACT LT1585ACT-3.3
TYPICAL APPLICATION
3.3V, 5A Regulator
1.5
VIN 4.75V LT1585A-3.3 3.3V 5A C2* 10F
Dropout Voltage vs Output Current
1.4
+
INPUT/OUTPUT DIFFERENTIAL (V)
C1 10F
+
1.3 1.2 1.1 1.0 0.9 0.8 0.7 0.6 0.5 0 OUTPUT CURRENT (A)
LT1585A TA02
* REQUIRED FOR STABILITY
1585A TA01
NOTE: MICROPROCESSOR APPLICATIONS WITH LOAD TRANSIENTS OF 3.8A REQUIRE OUTPUT DECOUPLING CAPACITANCE >1300F ON FIXED VOLTAGE PARTS TO ACHIEVE < 50mV OF DEVIATION FROM NOMINAL OUTPUT. CONSULT FACTORY FOR DETAILS
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IFULL LOAD
1
LT1585A/LT1585A-3.3
ABSOLUTE MAXIMUM RATINGS
PRECONDITIONI G
100% Thermal Limit Functional Test
PACKAGE/ORDER INFORMATION
FRONT VIEW 3 2 1 T PACKAGE 3-LEAD PLASTIC TO-220 VIN VOUT ADJ
ORDER PART NUMBER LT1585ACT
FRONT VIEW 3 2 1 T PACKAGE 3-LEAD PLASTIC TO-220
JA = 50C/W
JA = 50C/W
Consult factory for Industrial and Military grade parts.
ELECTRICAL CHARACTERISTICS
PARAMETER Reference Voltage LT1585A Output Voltage Line Regulation (Notes 1, 2) Load Regulation (Notes 1, 2, 3) Dropout Voltage LT1585A-3.3 LT1585A LT1585A-3.3 LT1585A LT1585A-3.3 LT1585A LT1585A-3.3 LT1585A LT1585A-3.3 Current Limit (Note 3) LT1585A LT1585A-3.3 CONDITIONS (VIN - VOUT) = 3V, TJ = 25C, IOUT = 10mA 1.5V (VIN - VOUT) 5.75V, 10mA IOUT 5A VIN = 5V, TJ = 25C, IOUT = 0mA 4.75V VIN 7V, 0mA IOUT 5A 2.75V VIN 7V, IOUT = 10mA 4.75V VIN 7V, IOUT = 0mA
q q q
MIN 1.238 (-1%) 1.225 (-2%) 3.267 (-1%) 3.235 (- 2%)
(VN - VOUT) = 3V, TJ = 25C, 10mA IOUT IFULL LOAD VIN = 5V, TJ = 25C, 0mA IOUT IFULL LOAD
q
VREF = 1%, IOUT = 3A VOUT = 1%, IOUT = 3A
q
VREF = 1%, IOUT = 5A VOUT = 1%, IOUT = 5A
q
(VIN - VOUT) = 5.5V (VIN - VOUT) = 5.5V
q
Adjust Pin Current LT1585A Adjust Pin Current LT1585A Change (Note 3) Minimum Load Current LT1585A 1.5V (VIN - VOUT) 5.75V, 10mA IOUT IFULL LOAD 1.5V (VIN - VOUT) 5.75V VIN = 5V
q q q q
Quiescent Current LT1585A-3.3
2
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5.0
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VIN ............................................................................. 7V Operating Junction Temperature Range Control Section.................................... 0C to 125C Power Transistor ................................. 0C to 150C
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Storage Temperature Range ................. - 65C to 150C Lead Temperature (Soldering, 10 sec).................. 300C
ORDER PART NUMBER
VIN VOUT GND
LT1585ACT-3.3
TYP 1.250 1.250 3.300 3.300
MAX 1.262 (+1%) 1.275 (+2%) 3.333 (+1%) 3.365 (+ 2%)
UNITS V V V V
0.005 0.05 0.05
0.2 0.3 0.5
% % %
1.150
1.300
V
1.200
1.400
V
6.0 55 0.2 2 8 120 5 10 13
A A A mA mA
LT1585A/LT1585A-3.3
ELECTRICAL CHARACTERISTICS
PARAMETER Ripple Rejection LT1585A LT1585A-3.3 CONDITIONS f = 120Hz, COUT = 25F Tant., (VIN - VOUT) = 3V, IOUT = 5A f = 120Hz, COUT = 25F Tant., VIN = 6.3V, IOUT = 5A
q
MIN
TYP
MAX
UNITS
60
72
dB
Thermal Regulation Temperature Stability Long-Term Stability RMS Output Noise (% of VOUT) Thermal Resistance Junction to Case
LT1585A LT1585A-3.3
TA = 25C, 30ms Pulse TA = 25C, 30ms Pulse 0.004
q
0.02 1.0
%/W % % %
0.5 0.03 0.003 0.7/3.0
TA = 125C, 1000 Hrs. TA = 25C, 10Hz f 10kHz LT1585A T Package: Control Circuitry/Power Transistor
C/W
The q denotes specifications which apply over the specified operating temperature range. Note 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. Note 2: Line and load regulation are guaranteed up to the maximum power dissipation 28.8W for the LT1585A in T package. 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. Note 3: 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 5A for the LT1585A/LT1585A-3.3. The LT1585A has constant current limit with changes in input-to-output voltage.
TYPICAL PERFORMANCE CHARACTERISTICS
LT1585A Dropout Voltage vs Output Current
1.5 1.4 1.3 GUARANTEED TEST POINTS T = -5C
OUTPUT VOLTAGE DEVIATION (%)
SHORT-CIRCUIT CURRENT (A)
DROPOUT VOLTAGE (V)
1.2 1.1 1.0 0.9 0.8 0.7 0.6 0.5 0 1 3 4 2 OUTPUT CURRENT (A) 5 T = 25C T = 125C
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LT1585A Short-Circuit Current vs Temperature
6.0
LT1585A Load Regulation vs Temperature
0.10 0.05 0 -0.05 -0.10 -0.15 -0.20 -75 -50 -25 0 25 50 75 100 125 150 175 TEMPERATURE (C)
LT1585A * TPC03
I = 5A
5.5
5.0
4.5
4.0 -75 -50 -25 0 25 50 75 100 125 150 175 TEMPERATURE (C)
LT1585A * TPC02
LT1585A * TPC01
3
LT1585A/LT1585A-3.3 TYPICAL PERFORMANCE CHARACTERISTICS
LT1585A Reference Voltage vs Temperature
1.275 1.270
3.70 3.65 3.60
REFERENCE VOLTAGE (V)
1.265 1.260 1.255 1.250 1.245 1.240 1.235 1.230 1.225 -75 -50 -25 0 25 50 75 100 125 150 175 TEMPERATURE (C)
LT1585A * TPC04
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
LT1585A Minimum Load Current vs Temperature
5 100 90
MINIMUM LOAD CURRENT (mA)
ADJUST PIN CURRENT (A)
QUIESCENT CURRENT (mA)
4
3
2
1
0 -75 -50 -25 0 25 50 75 100 125 150 175 TEMPERATURE (C)
LT1585A * TPC07
LT1585A-3.3 Ripple Rejection vs Frequency
90 80
RIPPLE REJECTION (dB)
70 60 50 40 30 20 10 0 10 LT1585A-3.3: (VIN - VOUT) 3V 0.5V VRIPPLE 2V IOUT = IFULL LOAD 100 1k 10k FREQUENCY (Hz) 100k
POWER (W)
4
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Output Voltage vs Temperature Using Adjustable LT1585A
VOUT SET WITH 1% RESISTORS VOUT = 3.6V
LT1585A-3.3 Output Voltage vs Temperature
3.35 3.34 3.33 3.32 3.31 3.30 3.29 3.28 3.27 3.26 3.25 -75 -50 -25 0 25 50 75 100 125 150 175 TEMPERATURE (C)
LT1585A * TPC06
3.55 3.50 3.45 3.40 3.35 3.30 3.25 3.20 -75 -50 -25 0 25 50 75 100 125 150 175 TEMPERATURE (C)
LT1585A * TPC05
VOUT = 3.45V VOUT = 3.38V VOUT = 3.3V
VOUT = 3.3V
LT1585A Adjust Pin Current vs Temperature
13 12 11 10 9 8 7 6 5 4
LT1585A-3.3 Quiescent Current vs Temperature
80 70 60 50 40 30 20 10 0 -75 -50 -25 0 25 50 75 100 125 150 175 TEMPERATURE (C)
LT1585A * TPC08
3 -75 -50 -25 0 25 50 75 100 125 150 175 TEMPERATURE (C)
LT1585A * TPC09
LT1585A Maximum Power Dissipation*
30 25 20 15 10 5 0 50 60 70 80 90 100 110 120 130 140 150 CASE TEMPERATURE (C)
LT1585A * TPC11
LT1585A * TPC10
*AS LIMITED BY MAXIMUM JUNCTION TEMPERATURE
LT1585A/LT1585A-3.3
SI PLIFIED SCHE ATIC
VIN
APPLICATIONS INFORMATION
General The LT1585A/LT1585A-3.3 3-terminal regulators are easy to use and have all the protection features expected in high performance linear regulators. The devices are short-circuit protected, safe-area protected and provide thermal shutdown to turn off the regulators should the junction temperature exceed about 150C. The regulators include an adjustable and a fixed 3.3V version. 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 LT1585A/LT1585A-3.3 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 response as part of the specification. The LT1585A/ LT1585A-3.3 are specifically designed to meet the fast current load-step requirements of these microprocessors and save total cost by needing less output capacitance in order to maintain regulation. Stability The circuit design in the LT1585A/LT1585A-3.3 requires the use of an output capacitor as part of the frequency compensation. For all operating conditions, the addition of a 22F solid tantalum or a 100F aluminum electrolytic on the output ensures stability. Normally, the LT1585A/ LT1585A-3.3 can use smaller value capacitors. Many different types of capacitors are available and have widely varying characteristics. These capacitors differ in capaci-
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THERMAL LIMIT
VOUT
ADJ
GND
LT1585A * BD
FOR FIXED VOLTAGE DEVICE
5
LT1585A/LT1585A-3.3
APPLICATIONS INFORMATION
tor tolerance (sometimes ranging up to 100%), equivalent series resistance, equivalent series inductance and capacitance temperature coefficient. The LT1585A/ LT1585A-3.3 frequency compensation optimizes frequency response with low ESR capacitors. In general, use capacitors with an ESR of less than 1. On the adjustable LT1585A, bypassing the adjust terminal improves ripple rejection and transient response. Bypassing the adjust pin increases the required output capacitor value. The value of 22F tantalum or 100F 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 LT1585A/ LT1585A-3.3. Large load current changes are exactly the situation presented 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 instantaneous step in output voltage (V = I * ESR). The ESL of the output capacitors produces a droop proportional to the rate of change of output current (V = L * I/t). The output capacitance produces a change in output voltage proportional to the time until the regulator can respond (V = t * I/C). These transient effects are illustrated in Figure 1. 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 microproESR EFFECTS ESL EFFECTS V I = t C CAPACITANCE EFFECTS
LT1585A * F01
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SLOPE,
POINT AT WHICH REGULATOR TAKES CONTROL
Figure 1
cessors. These requirements dictate a combination of high quality, surface mount tantalum capacitors and ceramic capacitors. 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 cavity. 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 LT1585A/ LT1585A-3.3 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 capacitors for the regulators are mounted several inches from the terminals. Protection Diodes In normal operation, the LT1585A/LT1585A-3.3 do not require any protection diodes. Older 3-terminal regulators require protection diodes between the output pin and the input pin or between the adjust pin and the output pin to prevent die overstress. On the adjustable LT1585A, 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.
LT1585A/LT1585A-3.3
APPLICATIONS INFORMATION
A protection diode between the input and output pins is usually not needed. An internal diode between the input and output pins on the LT1585A/LT1585A-3.3 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 of the LT1585A/LT1585A-3.3 can generate those levels of current, and a diode from output to input is then recommended. 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-tooutput voltage differential causes the internal transistors to break down and none of the protection circuitry is then functional.
D1 1N4002 (OPTIONAL)
VIN
+
LT1585A-3.3 IN OUT C1 10F GND
+
VOUT C2 10F
D1 1N4002 (OPTIONAL)
VIN
+
IN C1 10F
LT1585A OUT ADJ R1 R2
+
+
CADJ
LT1585A * F02
Figure 2
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Ripple Rejection The typical curve for ripple rejection reflects values for the LT1585A-3.3 fixed output voltage part. In applications that require improved ripple rejection, use the adjustable device. A bypass capacitor from the adjust pin 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 2. 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 LT1585A adjustable regulator develops a 1.25V reference voltage between the output pin and the adjust pin (see Figure 3). 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 55A. Its output voltage contribution is small and only needs consideration when very precise output voltage setting is required.
LT1585A OUT ADJ IADJ 55A VREF R1
VIN
+
IN C1 10F
+
VOUT C2 10F
VOUT C2 10F
VOUT = VREF (1 + R2/R1) + IADJ (R2)
R2
LT1585A * F03
Figure 3. Basic Adjustable Regulator
7
LT1585A/LT1585A-3.3
APPLICATIONS INFORMATION
Load Regulation It is not possible to provide true remote load sensing because the LT1585A/LT1585A-3.3 are 3-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 4. 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 5 illustrates this point. If R1 connects to the load, the effective resistance between the regulator and the load is: RP(1 + R2/R1), RP = Parasitic Line Resistance The connection shown in Figure 5 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.
VIN
LT1585A-3.3 IN OUT GND
Figure 4. Connection for Best Load Regulation
VIN
IN ADJ
*CONNECT R1 TO CASE CONNECT R2 TO LOAD
Figure 5. Connection for Best Load Regulation
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RP PARASITIC LINE RESISTANCE
RL
LT1585A * F04
LT1585A OUT
RP PARASITIC LINE RESISTANCE
R1* RL R2*
LT1585A * F05
LT1585A/LT1585A-3.3
APPLICATIONS INFORMATION
Thermal Considerations The LT1585A/LT1585A-3.3 family protects the device 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 caseto-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. Older regulators, with a single junction-to-case thermal resistance specification, use an average of the two values provided here and allow excessive junction temperatures under certain conditions of ambient temperature and heat sink resistance. Calculate the maximum junction temperature for both sections to ensure that both thermal limits are met. 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. Linear Technology strongly recommends thermal compound at the case-to-heat sink interface. Use a thermally conductive spacer if the case of the device must be electrically isolated and include its 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 both the LT1585A and the LT1585A-3.3. For example, using an LT1585ACT-3.3 (TO-220, commercial) and assuming: VIN(Max Continuous) = 5.25V (5V + 5%), VOUT = 3.3V, IOUT = 5A TA = 70C, HEAT SINK = 3C/W CASE-TO-HEAT SINK = 1C/W (with Thermal Compound) Power dissipation under these conditions is equal to: PD = (VIN - VOUT)(IOUT) = (5.25 - 3.3)(5) = 9.75W Junction temperature will be equal to: TJ = TA + PD(HEAT SINK + CASE-TO-HEAT SINK + JC) For the Control Section: TJ = 70C + 9.75W (3C/W + 1C/W + 0.7C/W) = 115.8C 115.8C < 125C = TJMAX (Control Section Commercial range) For the Power Transistor: TJ = 70C + 9.75W (3C/W + 1C/W + 3C/W) = 138.3C 138.3C < 150C = TJMAX (Power Transistor Commercial Range) In both cases the junction temperature is below the maximum rating for the respective sections, ensuring reliable operation.
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LT1585A/LT1585A-3.3
TYPICAL APPLICATIONS N
4.75V TO 5.25V
C1 TO C3 220F 10V AVX TPS 3 EACH
VOUT 50mV/DIV
IOUT 2A/DIV
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Minimum Parts Count LT1585A Adjustable Circuit for the Intel 120MHz Pentium Processor
THERMALLOY 7020B-MT IN OUT R1 110 0.1% R2 197 0.1%
PLACE IN MICROPROCESSOR SOCKET CAVITY 3.50V 5A
+
LT1585ACT ADJ
+
C4 330nF 16V AVX X7R 0805
C5 TO C10 100F 10V AVX TPS 4 EACH
C11 TO C20 1F 16V AVX Y5V 0805 24 EACH
LT1585A TA04
AVX CORP. (803) 448-9411 THERMALLOY INC. (214) 243-4321 DO NOT SUBSTITUTE COMPONENTS.
LT1585A Transient Response for 3.8A Load Current Step*
100s/DIV
LT1584A * TA05
*TRANSIENT RESPONSE MEASURED WITH AN INTEL POWER VALIDATOR. VOUT IS MEASURED AT THE POWER VALIDATOR
LT1585A/LT1585A-3.3
TYPICAL APPLICATIONS N
Guaranteed LT1585A Circuit for the Intel 100MHz and Higher Frequency Pentium Processors (Meets Intel Specifications with Worst-Case Tolerances)
5V SEE NOTE 5 3
THERMALLOY 7021B-MT IN OUT LT1585A ADJ 1 R1 1k C6 R2 0.01F 1k SENSE R3D 5 R3E 6 83 117 SEE NOTE 7 4 R3C 800 3 R3B 1.35k 2 R3A 1.15k 1 SGND PGND PGND
LT1584 * TA06
2 SEE NOTE 6 R4
+ 220F
C2 TO C4 10V AVX TPS 3 EACH
C5 33pF NPO
C1 0.1F
2 1 COMP COL 3+ 8 REF V LT1431S 4 7 RM RT SGND FGND 5 6
VOUT 50mV/DIV
IOUT 2A/DIV
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 representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
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PLACE IN MICROPROCESSOR SOCKET CAVITY VOUT
+
C8 TO C13 100F + 10V AVX TPS 4 EACH
C14 TO C23 1F 16V AVX Y5V 0805 24 EACH
+ C7
100F 10V
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 0 JUMPER RESISTOR R4 7. R3A TO R3E ARE B.I. TECHNOLOGY 627V100
LT1585A/LT1431 Transient Response for 3.8A Load Current Step*
100s/DIV
LT1584A * TA06
*TRANSIENT RESPONSE MEASURED WITH AN INTEL POWER VALIDATOR. VOUT IS MEASURED AT THE POWER VALIDATOR
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LT1585A/LT1585A-3.3
PACKAGE DESCRIPTION
0.390 - 0.415 (9.906 - 10.541)
0.460 - 0.500 (11.684 - 12.700)
0.980 - 1.070 (24.892 - 27.178)
0.520 - 0.570 (13.208 - 14.478)
0.090 - 0.110 (2.286 - 2.794) 0.028 - 0.038 (0.711 - 0.965)
RELATED PARTS
PART NUMBER LTC1430 LT1580 LT1584 LT1587 DESCRIPTION High Power Step-Down Switching Regulator 7A Very Low Dropout Linear Regulator 7A Low Dropout Fixed and Adjustable Linear Regulators 3A Low Dropout Fixed and Adjustable Linear Regulators COMMENTS 5V to 3.3V at 10A 0.54V Dropout at 7A, Fixed 2.5VOUT and Adjustable Fast Transient Response for Microprocessor Applications Fast Transient Response for Microprocessor Applications
12
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7487
(408) 432-1900 q FAX: (408) 434-0507 q TELEX: 499-3977
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Dimensions in inches (millimeters) unless otherwise noted. T Package 3-Lead Plastic TO-220
0.147 - 0.155 (3.734 - 3.937) DIA 0.230 - 0.270 (5.842 - 6.858) 0.570 - 0.620 (14.478 - 15.748) 0.330 - 0.370 (8.382 - 9.398) 0.165 - 0.180 (4.293 - 4.699)
0.045 - 0.055 (1.143 - 1.397)
0.218 - 0.252 (5.537 - 6.401) 0.013 - 0.023 (0.330 - 0.584) 0.050 (1.270) TYP
0.095 - 0.115 (2.413 - 2.921)
T3 (TO-220) 0595
LT/GP 1095 10K * PRINTED IN USA
(c) LINEAR TECHNOLOGY CORPORATION 1995

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