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Part: AMS1505CMV-3.5
Category:
Description: 3.5V 5A Ultra Low Dropout Voltage Regulator
Company: Advanced Monolithic Systems
Datasheet: Download AMS1505CMV-3.5 datasheet File size : 261 kB
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Datasheet text preview:
Advanced Monolithic Systems
FEATURES
· Adjustable or Fixed Output 1.5V, 2.5V, 2.85V, 3.0V, 3.3V, 3.5V and 5.0V · Output Current of 5A · Low Dropout, 500mV at 5A Output Current · Fast Transient Response · Remote Sense
AMS1505
5A LOW DROPOUT VOLTAGE REGULATORS
APPLICATIONS
· High Current Regulators · Post Regulators for Switching Supplies · Microprocessor Supply · Adjustable Power Supply · Notebook/Personal Computer Supplies
GENERAL DESCRIPTION
The AMS1505 series of adjustable and fixed low dropout voltage regulators are designed to provide 5A output current to The power the new generation of microprocessors. The dropout voltage of the device is 100mV at light loads and rising to 500mV at maximum output current. A second low current input voltage 1V or greater then the output voltage is required to achieve this dropout. The AMS1505 can also be used as a single supply device. New features have been added to the AMS1505: a remote Sense pin is brought out virtually eliminating output voltage variations due to load changes. The typical load regulation, measured at the Sense pin, for a load current step of 100mA to 5A is less than 1mV. The AMS1505 series has fast transient response. The Adjust pin is brought out on fixed devices. To further improve the transient response the addition of a small capacitor on the Adjust pin is recommended. The AMS1505 series are ideal for generating processor supplies of 2V to 3V on motherboards where both 5V and 3.3V supplies are available. The AMS1505 devices are offered in 5 lead TO-220, 5L TO-263 (plastic DD) and 5L TO-252 (DPAK) packages.
ORDERING INFORMATION:
OPERATING JUNCTION 5 LEAD TO-263 5 LEAD TO-220 5 LEAD TO-252 TEMPERATURE RANGE AMS1505CM AMS1505CT AMS1505CD 0 to 125° C AMS1505CM-1.5 AMS1505CT-1.5 AMS1505CD-1.5 0 to 125° C AMS1505CM-2.5 AMS1505CT-2.5 AMS1505CD-2.5 0 to 125° C AMS1505CM-2.85 AMS1505CT-2.85 AMS1505CD-2.85 0 to 125° C AMS1505CM-3.0 AMS1505CT-3.0 AMS1505CD-3.0 0 to 125° C AMS1505CM-3.3 AMS1505CT-3.3 AMS1505CD-3.3 0 to 125° C AMS1505CM-3.5 AMS1505CT-3.5 AMS1505CD-3.5 0 to 125° C AMS1505CM-5.0 AMS1505CT-5.0 AMS1505CD-5.0 0 to 125° C PACKAGE TYPE
PIN CONNECTIONS
5 LEAD TO-220
5 4 3 2 1 VPOWER VCONTROL OUTPUT ADJUST/GND SENSE
FRONT VIEW 5 LEAD TO-252
5 4 3 2 1 V power V control OUTPUT ADJUST/GND SENSE
FRONT VIEW
5 LEAD TO-263
5 4 3 2 1 V power V control OUTPUT ADJUST/GND SENSE
FRONT VIEW
Advanced Monolithic Systems, Inc.
www.advanced-monolithic.com
Phone (925) 443-0722
Fax (925) 443-0723
AMS1505
ABSOLUTE MAXIMUM RATINGS (Note 1)
VPOWER Input Voltage 7V VCONTROL Input Voltage 13V Operating Junction Temperature Range Control Section 0°C to 125°C Power Transistor 0°C to 150°C Storage temperature - 65°C to +150°C Soldering information Lead Temperature (10 sec) Thermal Resistance TO-220 package TO-252 package TO-263 package
*Minimum pad size is 0.038in2
JA= 50°C/W JA= 92°C/W* JA= 30°C/W**
** With package soldering to 0.5in2 copper area over backside ground plane or internal power plane JA can vary from 20°C/W to >40°C/W depending on mounting technique.
300°C
ELECTRICAL CHARACTERISTICS
Electrical Characteristics at ILOAD = 0 mA, and TJ = +25°C unless otherwise specified. Parameter
Reference Voltage
Device
AMS1505
Conditions
VCONTROL = 2.75V, VPOWER =2V, ILOAD = 10mA VCONTROL = 2.7V to 12V, VPOWER =3.3V to 5.5V, ILOAD = 10mA to 5A VCONTROL = 4V, VPOWER =2.V, ILOAD = 0mA VCONTROL = 3V, VPOWER =2.3V, ILOAD = 0mA to 5A VCONTROL = 5V, VPOWER =3.3V, ILOAD = 0mA VCONTROL = 4V, VPOWER =3.3V, ILOAD = 0mA to 5A VCONTROL = 5.35V, VPOWER =3.35V, ILOAD = 0mA VCONTROL = 4.4V, VPOWER =3.7V, ILOAD = 0mA to 5A VCONTROL = 5.5V, VPOWER =3.5V, ILOAD = 0mA VCONTROL = 4.5V, VPOWER =3.8V, ILOAD = 0mA to 5A VCONTROL = 5.8V, VPOWER =3.8V, ILOAD = 0mA VCONTROL = 4.8V, VPOWER =4.1V, ILOAD = 0mA to 5A VCONTROL = 6V, VPOWER =4V, ILOAD = 0mA VCONTROL = 5V, VPOWER =4.3V, ILOAD = 0mA to 5A VCONTROL = 7.5V, VPOWER =5.5V, ILOAD = 0mA VCONTROL = 6.5V, VPOWER =5.8V, ILOAD = 0mA to 5A ILOAD = 10 mA , 1.5V (VCONTROL - VOUT) 12V 0.8V (VPOWER - VOUT) 5.5V VCONTROL = VOUT + 2.5V, VPOWER =VOUT + 0.8V, ILOAD = 10mA to 5A VCONTROL = 5V, VPOWER =3.3V, VADJ = 0V (Note 3) VCONTROL = VOUT + 2.5V, VPOWER =VOUT + 0.8V, ILOAD = 10mA to 5A VCONTROL = VOUT + 2.5V, VPOWER =VOUT + 0.8V, ILOAD = 10mA to 5A VCONTROL = 2.75V, VPOWER = 2.05V, ILOAD = 10mA (VIN - VOUT) = 5V
Min
1.243 1.237 1.491 1.485 2.485 2.475 2.821 2.833 2.982 2.970 3.280 3.235 3.479 3.430 4.930 4.950
Typ
1.250 1.250 1.500 1.500 2.500 2.500 2.850 2.850 3.000 3.000 3.300 3.300 3.500 3.500 5.000 5.000 1
Max
1.258 1.263 1.509 1.515 2.515 2.525 2.879 2.867 3.018 3.030 3.320 3.333 3.521 3.535 5.030 5.050 3
Units
V V V V V V V V V V V V V V V V mV
Output Voltage
AMS1505-1.5
AMS1505-2.5 AMS1505-2.85 AMS1505-3.0 AMS1505-3.3 AMS1505-3.5 AMS1505-5.0 Line Regulation AMS1505/-1.5/-2.5/ -2.85/-3.0/-3.3/-3.5/-5.0 Load Regulation AMS1505/-1.5/-2.5/ -2.85/-3.0/-3.3/-3.5/-5.0 Minimum Load Current Control Pin Current (Note 4) Ground Pin Current (Note 4) Adjust Pin Current Current Limit AMS1505 AMS1505/-1.5/-2.5/ -2.85/-3.0/-3.3/-3.5/-5.0 AMS1505/-1.5/-2.5/ -2.85/-3.0/-3.3/-3.5/-5.0 AMS1505 AMS1505/-1.5/-2.5/ -2.85/-3.0/-3.3/-3.5/-5.0 Ripple Rejection AMS1505/-1.5/-2.5/ -2.85/-3.0/-3.3/-3.5/-5.0 Thermal Regulation Thermal Resistance Junction-to-Case AMS1505
1
5
mV
5 50
10 85
mA mA
6
10
mA
50 7.1 8.0
120
µA A
VCONTROL = VPOWER = VOUT + 2.5V, VRIPPLE = 1VP-P ILOAD = 2A TA = 25°C, 30ms pulse T Package: Control Circuitry/ Power Transistor M & D Package: Control Circuitry/ Power Transistor
60
80
dB
0.002
0.020 0.65/2.70 0.65/2.70
%W °C/W °C/W
Advanced Monolithic Systems, Inc.
www.advanced-monolithic.com
Phone (925) 443-0722
Fax (925) 443-0723
AMS1505
ELECTRICAL CHARACTERISTICS
Electrical Characteristics at IOUT = 0 mA, and TJ = +25°C unless otherwise specified. Parameter
Dropout Voltage Control Dropout (VCONTROL - VOUT) Power Dropout (VPOWER - VOUT) AMS1505/-1.5/-2.5/ -2.85/-3.0/-3.3/-3.5/-5.0 AMS1505/-1.5/-2.5/ -2.85/-3.0/-3.3/-3.5/-5.0
Device
Conditions
Note 2 VPOWER =VOUT + 0.8V, ILOAD = 10mA VPOWER =VOUT + 0.8V, ILOAD = 5A VCONTROL =VOUT + 2.5V, ILOAD = 10mA VCONTROL =VOUT + 2.5V, ILOAD = 5A
Min
Typ
Max
Units
1.00 1.15 .10 .45
1.15 1.30 0.17 0.50
V V V V
Parameters identified with boldface type apply over the full operating temperature range.
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. For guaranteed specifications and test conditions, see the
Electrical Characteristics. The guaranteed specifications apply only for the test conditions listed.
Note 2: Unless otherwise specified VOUT = VSENSE. For the adjustable device VADJ = 0V. Note 3: The dropout voltage for the AMS1505 is caused by either minimum control voltage or minimum power voltage. The specifications represent the minimum
input/output voltage required to maintain 1% regulation.
Note 4: For the adjustable device the minimum load current is the minimum current required to maintain regulation. Normally the current in the resistor divider
used to set the output voltage is selected to meet the minimum load current requirement.
Note 5: The control pin current is the drive current required for the output transistor. This current will track output current with a ratio of about 1:100. The
minimum value is equal to the quiescent current of the device.
PIN FUNCTIONS
Sense (Pin 1): This pin is the positive side of the reference voltage for the device. With this pin it is possible to Kelvin sense the output voltage at the load. Adjust (Pin 2/5): This pin is the negative side of the reference voltage for the device. Adding a small bypass capacitor from the Adjust pin to ground improves the transient response. For fixed voltage devices the Adjust pin is also brought out to allow the user to add a bypass capacitor. GND (Pin 2/5): For fixed voltage devices this is the bottom of the resistor divider that sets the output voltage. VPOWER (Pin 5/6): This pin is the collector to the power device of the AMS1505. The output load current is supplied through this pin. The voltage at this pin must be between 0.1V and 0.8V greater than the output voltage for the device to regulate. VCONTROL (Pin 4/3): This pin is the supply pin for the control circuitry of the device. The current flow into this pin will be about 1% of the output current. The voltage at this pin must be 1.3V or greater than the output voltage for the device to regulate. Output (Pin 3/4): This is the power output of the device.
Advanced Monolithic Systems, Inc.
www.advanced-monolithic.com
Phone (925) 443-0722
Fax (925) 443-0723
AMS1505
APPLICATION HINTS
The AMS1505 series of adjustable and fixed regulators are designed to power the new generation of microprocessors. The AMS1505 is designed to make use of multiple power supplies, existing in most systems, to reduce the dropout voltage. One of the advantages of the two supply approach is maximizing the efficiency. The second supply is at least 1V greater than output voltage and is providing the power for the control circuitry and supplies the drive current to the NPN output transistor. This allows the NPN to be driven into saturation; thereby reducing the dropout voltage by a VBE compared to conventional designs. For the control voltage the current requirement is small equal to about 1% of the output current or approximately 50mA for a 5A load. Most of this current is drive current for the NPN output transistor. This drive current becomes part of the output current. The maximum voltage on the Control pin is 13V. The maximum voltage at the Power pin is 7V. Ground pin current for fixed voltage devices is typical 6mA and is constant as a function of load. Adjust pin current for adjustable devices is 60µA at 25°C and varies proportional to absolute temperature. The improved frequency compensation of AMS1505 permits the use of capacitors with very low ESR. This is critical in addressing the needs of modern, low voltage high sped microprocessors. The new generation of microprocessors cycle load current from several hundred mA to several A in tens of nanoseconds. Output voltage tolerances are tighter and include transient response as part of the specification. Designed to meet the fast current load step requirements of these microprocessors, the AMS1505 also saves total cost by needing less output capacitance to maintain regulation. Careful design of the AMS1505 has eliminated any supply sequencing issues associated with a dual supply system. The output voltage will not turn on until both supplies are operating. If the control voltage comes up first, the output current will be limited to a few milliamperes until the power input voltage comes up. If power input comes up first the output will not turn on at all until the control voltage comes up. The output can never come up unregulated. By tying the control and power inputs together the AMS1505 can also be operated as a single supply device. In single supply operation the dropout will be determined by the minimum control voltage. The new features of the AMS1505 require additional pins over the traditional 3-terminal regulator. Both the fixed and adjustable versions have remote sense pins, permitting very accurate regulation of output voltage at the load, rather than at the regulator. As a result, over an output current range of 100mA to 5A with a 2.5V output, the typical load regulation is less than 1mV. For the fixed voltages the adjust pin is brought out allowing the user to improve transient response by bypassing the internal resistor divider. Optimum transient response is provided using a capacitor in the range of 0.1µF to 1µF for bypassing the Adjust pin. The value chosen will depend on the amount of output capacitance in the system. In addition to the enhancements mentioned, the reference accuracy has been improved by a factor of two with a guaranteed initial tolerance of ±0.6% at 25°C. This device can hold 1% accuracy over the full temperature range and load current range, guaranteed, when combined with ratiometrically accurate internal divider resistors and operating with an input/output differential of well under 1V. Typical applications for the AMS1505 include 3.3V to 2.5V conversion with a 5V control supply, 5V to 4.2V conversion with a 12V control supply or 5V to 3.6V conversion with a 12V control supply. Capable of 5A of output current with a maximum dropout of 0.8V the AMS1505 also has a fast transient response that allows it to handle large current changes associated with the new generation of microprocessors. The device is fully protected against overcurrent and overtemperature conditions. Grounding and Output Sensing The AMS1505 allows true Kelvin sensing for both the high and low side of the load. As a result the voltage regulation at he load can be easily optimized. Voltage drops due to parasitic resistances between the regulator and the load can be placed inside the regulation loop of the AMS1505. The advantages of remote sensing are illustrated in figures 1 through 3. Figure 1 shows the device connected as a conventional 3 terminal regulator with the Sense lead connected directly to the output of the device. RP is the parasitic resistance of the connections between the device and the load. Typically the load is a microprocessor and RP is made up of the PC traces and /or connector resistances (in the case of a modular regulator) between the regulator and the processor. Trace A of figure 3 illustrates the effect of RP. Very small resistances cause significant load regulation steps. Figure 2 shows the device connected to take advantage of the remote sense feature. The Sense pin and the top of the resistor divider are connected to the top of the load; the bottom of the resistor divider is connected to the bottom of the load. RP is now connected inside the regulation loop of the AMS1505 and for reasonable values of RP the load regulation at the load will be negligible. The effect on output regulation can be seen in trace B of figure 3. 5V
CONTROL POWER SENSE
3.3V
AMS1505
OUTPUT ADJ RP LOAD R1 R2 RP
+ VOUT -
Figure 1. Conventional Load Sensing
Advanced Monolithic Systems, Inc.
www.advanced-monolithic.com
Phone (925) 443-0722
Fax (925) 443-0723
AMS1505
APPLICATION HINTS
5V
CONTROL POWER SENSE
3.3V
AMS1505
OUTPUT ADJ RP LOAD R1 R2 RP
+ VOUT -
Figure 2. Remote Load Sensing
(IOUT)(RP) VOUT FIGURE 1 VOUT FIGURE 2
to allow this capability. To ensure good transient response with heavy load current changes capacitor values on the order of 100µF are used in the output of many regulators. To further improve stability and transient response of these devices larger values of output capacitor can be used. The modern processors generate large high frequency current transients. The load current step contains higher order frequency components than the output coupling network must handle until the regulator throttles to the load current level. Because they contain parasitic resistance and inductance, capacitors are not ideal elements. 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 the 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). Figure 4 illustrates these transient effects.
ESR EFFECTS ESL EFFECTS CAPACITANCE EFFECTS
IOUT TIME
SLOPE, V/t = I/C
POINT AT WHICH REGULATOR TAKES CONTROL
Figure 4. Figure 3. Remote Sensing Improves Load Regulation Voltage drops due to RP are not eliminated; they will add to the dropout voltage of the regulator regardless of whether they are inside or outside the regulation loop. The AMS1505 can control the voltage at the load as long as the input-output voltage is greater than the total of the dropout voltage of the device plus the voltage drop across RP. Stability The circuit design used in the AMS1505 series requires the use of an output capacitor as part of the device frequency compensation. The addition of 150µF aluminum electrolytic or a 22µF solid tantalum on the output will ensure stability for all operating conditions. For best frequency response use capacitors with an ESR of less than 1. In order to meet the transient requirements of the processor larger value capacitors are needed. Tight voltage tolerances are required in the power supply. To limit the high frequency noise generated by the processor high quality bypass capacitors must be used. In order to limit parasitic inductance (ESL) and resistance (ESR) in the capacitors to acceptable limits, multiple small ceramic capacitors in addition to high quality solid tantalum capacitors are required. When the adjustment terminal is bypassed to improve the ripple rejection, the requirement for an output capacitor increases. The Adjust pin is brought out on the fixed voltage device specifically Output Voltage The AMS1505 series develops a 1.25V reference voltage between the Sense pin and the Adjust pin (Figure5). Placing a resistor between these two terminals causes a constant current to flow through R1 and down through R2 to set the overall output voltage. In general R1 is chosen so that this current is the specified minimum load current of 10mA.The current out of the Adjust pin is small, typically 50µA and it adds to the current from R1. Because IADJ is very small it needs to be considered only when very precise output voltage setting is required. For best regulation the top of the resistor divider should be connected directly to the Sense pin.
VCONTROL
+
CONTROL POWER OUTPUT
V POWER
+
AMS1505 SENSE ADJ
+
VOUT
VREF
R1 R2
IADJ
50µA
VOUT = VREF (1+ R2/R1)+IADJR2 Figure 5. Setting Output Voltage
Advanced Monolithic Systems, Inc.
www.advanced-monolithic.com
Phone (925) 443-0722
Fax (925) 443-0723
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