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CM1581
5A LOW DROPOUT VOLTAGE REGULATOR
GENERAL DESCRIPTION
The CM1581 is a high performance low dropout regulator rated for 5A output current with fixed 1.8V/2.5V/3.3V/5.0V and adjustable output. It is designed for use in applications requiring low dropout characteristics over the rated current range. When the second low-current input voltage is applied, the dropout voltage can be as low as 100mV at light loads and up to 500mV at maximum output current. On chip trimming adjusts the reference voltage to 1%. These features are ideal for low voltage microprocessor applications requiring a regulated 1.8V to 3.6V power supply. In addition, the CM1581 provides the device protections including over current and thermal shutdown. The CM1581 series are ideal to the next generation microprocessor on motherboards where both 5V and 3.3V are available. ! ! ! ! ! !
FEATURES
! Input-Output differential of typical 500mV at 5A and low quiescent current Output Current is excess of 5A Remote sense pin available Reverse battery protection Short Circuit Protection Internal Thermal Overload Protection 5L TO-220 and 5L TO-263 package available
APPLICATIONS
! ! ! Power Supplies Computer Add-On Cards Other Applications Requiring Low Dropout Voltage Over Rated Current
PIN CONFIGURATION
TO-220 Top View TO-263 Top View
V PO W ER V CONTROL
GND/ADJ VCONTROL SENSE VPOWER
5 4 3 2 1
V OUT G N D /A D J SENSE
VOUT
12
3
4
5
2002/02/05 Preliminary Rev. 1
Champion Microelectronic Corporation
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CM1581
5A LOW DROPOUT VOLTAGE REGULATOR
ORDERING INFORMATION
Package Type TO-220 CM1581DCN220 CM1581KCN220 CM1581SCN220 CM1581ZJCN220 CM1581CN220 TO-263 CM1581DCN263 CM1581KCN263 CM1581SCN263 CM1581ZJCN263 CM1581CN263 Operating Temperature Range (TA) 0 ~ +70 0 ~ +70 0 ~ +70 0 ~ +70 0 ~ +70 Output Voltage 1.8V 2.5V 3.3V 5.0V ADJ.
ABSOLUTE MAXIMUM RATINGS
Input Voltage (Vpower) ............................................................... +13V Input Voltage (Vcontrol) ............................................................... +13V Operating Junction Temperature Range, TJ ..................... 0 to +150 Storage Temperature .................................................. -65 to +150 Lead Temperature (10 sec.) ......................................................... 300
POWER DISSIPATION TABLE
Package TO-220 TO-263 JA (/W) 45 45 Derating factor (mW/) TA >= 25 22.2 22.2 TA <= 25 Power rating (mW) 2775 2775 TA = 70 TA = 85 Power rating (mW) Power rating (mW) 1776 1443 1776 1443
Note: 1. JA : Thermal Resistance-Junction to Ambient, DF: Derating factor, PO: Power consumption.
2.
Junction Temperature Calculation: TJ = TA + (PD x JA ), PO = DF x (TJ - TA) The JA numbers are guidelines for the thermal performance of the device/PC-board system. All of the above assume no ambient airflow. JT : Thermal Resistance-Junction to Ambient, TC: case (Tab) temperature, TJ = TC + (PD x JC )
RECOMMENDED OPERATING CONDITIONS
Parameter Input Voltage (VIN) Load Current (with adequate heatsinking) Input Capacitor (VIN to GND) Output Capacitor with ESR of 10 max. (VOUT to GND) Symbol VPOWER VCONTROL IO Min. 2 2.75 10 10 33 Typ. Max 7 12 Units V V mA F F
2002/02/05 Preliminary Rev. 1
Champion Microelectronic Corporation
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CM1581
5A LOW DROPOUT VOLTAGE REGULATOR
BLOCK DIAGRAM
CM1581 Fixed Output Voltage Block Diagram
CM1581 Adjustable Output Voltage block Diagram
2002/02/05 Preliminary Rev. 1
Champion Microelectronic Corporation
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CM1581
5A LOW DROPOUT VOLTAGE REGULATOR
ELECTRICAL CHARACTERISTICS
Electrical Characteristics at IOUT = 0mA, and TJ = +25; unless otherwise noted CM1581 Min. 1.792 2.474 3.267 4.950 1.771 IOUT = 5A 2.460 3.247 4.920 1.238 1.230 Typ. 1.800 2.500 3.300 5.000 1.800 2.500 3.300 5.000 1.250 1.250 0.04 0.08 1.00 1.15 0.10 0.45 50 80 5.1 6.8 5 60 80 0.003 10 Max. 1.818 2.525 3.333 5.050 1.829 2.540 3.353 5.080 1.262 1.270 0.20 0.3 1.15 1.30 0.17 0.50 120 135 Parameter Device CM1581D Output Voltage CM1581K CM1581S CM1581ZJ CM1581D Output Voltage CM1581K CM1581S CM1581ZJ Reference Voltage CM1581(adj) Test Conditions VCONTROL = 3.3V, VPOWER = 2.5V VCONTROL = 5.0V, VPOWER = 3.3V VCONTROL = 5.8V, VPOWER = 3.8V VCONTROL = 7.5V, VPOWER = 5.5V VCONTROL = 3.3V, VPOWER = 2.5V VCONTROL = 5.0V, VPOWER = 3.3V VCONTROL = 5.0V, VPOWER = 4.1V VCONTROL = 6.5V, VPOWER = 5.8V VCONTROL = 5.0V, VPOWER = 3.3V (note1) VCONTROL = (VOUT + 1.5V) to 12V, VPOWER = (VOUT + 0.8V) to 7V, IOUT = 10mA to 5A Line Regulator (note 2) Load Regulation (note 2) Dropout Voltage (Note 3) VCONTROL - VOUT Dropout Voltage (Note 3) VPOWER - VOUT Adjust Pin Current Control Pin Current Current Limit Minimum Load Current (Note 4) Ripple Rejection (Note 5) Thermal Regulation Note 1: Output voltage is set to be 2.5V. Note 2: Line and load regulations are guaranteed up to maximum power dissipation determined by input/output differential and the output current. However, the maximum power will not be available over the full input/output voltage range. Note 3: The specifications represent the minimum input/output voltage required to maintain 1% regulation. Note 4: 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: These parameters, although guaranteed, are not tested in production prior to shipment. 1.5V+ VOUT <= VCONTROL <= 12V, 0.8V<= VPOWER - VOUT <= 5.5V VCONTROL = VOUT + 2.5V, VPOWER = VOUT + 0.8V, IOUT = 10mA to 5A VPOWER = VOUT + 0.8V VCONTROL = VOUT + 2.5V IOUT = 10mA IOUT = 5A IOUT = 10mA IOUT = 5A Unit V V V V V V V V V V % % V V A mA A mA dB %/W
VCONTROL = 2.75V, VPOWER = 2.05V, IOUT = 10mA VCONTROL = VOUT + 2.5V, VPOWER = VOUT + 0.8V, IOUT = 10mA to 5A (VIN - VOUT ) = 1.5V VCONTROL = 5.0V, VPOWER = 3.3V VCONTROL = VPOWER = VOUT + 2.5V, VRIPPLE = 1VPP, IOUT = 2.5A TA = 25
2002/02/05 Preliminary Rev. 1
Champion Microelectronic Corporation
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CM1581
5A LOW DROPOUT VOLTAGE REGULATOR
APPLICATION CIRCUIT
CM1581 Fixed Output Voltage Application Circuit
CM1581 Adjustable Output Voltage Application Circuit
2002/02/05 Preliminary Rev. 1
Champion Microelectronic Corporation
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CM1581
5A LOW DROPOUT VOLTAGE REGULATOR
APPLICATION INFORMATION
General The CM1581 series is designed to power the new generation of microprocessors. It is designed to make use of multiple power supplies, present 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 output transistor to be driven into saturation. For the control voltage the current requirement is small, about 1% of the output current or approximately 50mA for a 5A load. 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. By trying the control and power inputs together the CM1581 can be operated as a single supply device. In single supply operation, the dropout voltage will be determined by the minimum the Control voltage. The new generation of microprocessors cycle load current from several hundred milliampers to several amperes 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 CM1581 also saves total cost by needing less output capacitance to maintain regulation. The sense pin permits very accurate regulation of output voltage. As a result, over an output current range of 100mA to 5A, the typical load regulation is less than 1mV. In addition to the enhancements mentioned, the reference accuracy has been improved a factor of two with a guaranteed initial tolerance of 1% at 25 and 1.6% accuracy over the full temperature and load current load. Typical applications for the CM1581 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. It is easy to obtain dropout voltages of less than 0.5V at 2.5A along with excellent static and dynamic specifications. The device is fully protected against over current and over temperature conditions. Grounding and Output Sensing The CM1581 adjustable voltage version allows true Kelvin sensing for both the high and low side of the load. As a result the voltage regulation at the load can be easily optimized. Voltage drops due to parasitic resistances between the regulator and the load can be placed inside the regulation loop. 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. Trace A of figure 3 illustrates the effect of Rp. 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. The effect on the output regulation can be seen in trace B of figure 3. It is important to note that the voltage drops due to Rp are not eliminated; they will add to the dropout voltage of the regulator regardless. The CM1581 adjustable 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.
2002/02/05 Preliminary Rev. 1
Champion Microelectronic Corporation
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CM1581
5A LOW DROPOUT VOLTAGE REGULATOR
Stability The circuit design used in the CM1581 series requires the use of an output capacitor as part of the device frequency compensation. The addition of 150uF Aluminum electrolytic or a 22uF solid tantalum on the output will ensure stability for all operating conditions. In order to meet the transient performance of the processor larger value capacitors are needed. 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 capacitors to acceptable limits, multiple small ceramic capacitor 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. 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 and instantaneous step in output voltage at the beginning of a transient load step change. The ESR of the output capacitors produces an instantaneous step in out 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 an respond V = t(I/C). Figure 4 illustrates these transient effects.
2002/02/05 Preliminary Rev. 1
Champion Microelectronic Corporation
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CM1581
5A LOW DROPOUT VOLTAGE REGULATOR
Output Voltage The CM1581 adjustable version develops a 1.25V reference voltage between the Sense pin and the Adjust pin (Figure 5). Placing a resistor between these two terminals causes a constant current to flow through R1 and down through R2 to set the 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 50uA and it adds to the current for R1. For best regulation the top of the resistor divider should be connected directly to the Sense pin.
2002/02/05 Preliminary Rev. 1
Champion Microelectronic Corporation
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CM1581
5A LOW DROPOUT VOLTAGE REGULATOR
Protection Diodes In normal operation, CM1581 family does not need any protection diodes between the adjustment pin and the output and from the output to the input to prevent die overstress. Internal resistors are limiting the internal current paths on the ADJ pin. Therefore even with bypass capacitors on the adjust pin no protection diode is needed to ensure device safety under short-circuit conditions. The Adjust pin can be driver on a transient basis 7V with respect ti the output without any device degradation. A protection diode between the Output pin and VPOWER pin is not usually needed. Microsecond surge currents of 50A to 100A can be handled by the internal diode between the Output pin and VPOWER pin of the device. In normal operations, it is difficult to get those values of surge currents even with the use of large output capacitances. Only with high value output capacitors, such as 1000uF to 5000uF and the VPOWER pin is instantaneously shorted to ground, damage an occur. A diode from output to input is recommended (Figure 6). If CM1581 is connected as single supply device with the control and power input pins shorted together the internal diode between the output and power input pin will protect the control input pin. Thermal Consideration The CM1581 adjustable version had internal power and thermal limiting circuitry (about 150) designed to protect the device under overload conditions. However, maximum junction temperature ratings should not be exceeded under continuous normal load conditions. Careful consideration must be given to all sources of thermal resistance from junction to ambient, including junction-to-case, case-to-heatsink interface and heatsink resistance itself. Junction temperature of the Control section can run up to 125. Junction temperature rise in the power transistor will be greater than the temperature rise in the Control section making the thermal resistance lower in the Control section. At power levels below 12W, the temperature gradient will be lese than 25 and the maximum ambient temperature will be determined by the junction temperature of the Control section. This is due to the lower maximum junction temperature in the Control section. At power levels above 12W, the temperature gradient will be greater than 25 and the maximum ambient temperature will be determined by the Power section. In both cases, the junction temperature is determined by the total power dissipated in the device. For most low dropout applications the power dissipation will be less than 12W. The power in the device us made up of two components: the power in the output transistor and the power in the control circuit. The power in the control circuit is negligible, which is equal to: PCONTROL = (VCONTROL - VOUT)/ICONTROL, where ICONTROL is equal to IOUT/100(typ) The power in the output transistor is equal to: POUTPUT = (VPOWER - VOUT)/IOUT The total power is equal to: PCONTROL + POUTPUT 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 the heat flow. In order to ensure the best possible thermal flow this area of the package to the heatsink proper mounting is required. Thermal compound at the case-to-heatsink interface is recommended. A thermally conductive spacer can be used, if the case of the device must be electrically isolated, but its added contribution to thermal resistance has to be considered.
2002/02/05 Preliminary Rev. 1
Champion Microelectronic Corporation
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CM1581
5A LOW DROPOUT VOLTAGE REGULATOR
PACKAGE DIMENSION
TO-220 (N220)
B
F
C S
T
A B C
A
D F G J
12345
K N R S T
K
G N
D
R J
TO-263 (N263)
C A D I K G F L E
2002/02/05 Preliminary Rev. 1 Champion Microelectronic Corporation
B
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CM1581
5A LOW DROPOUT VOLTAGE REGULATOR
IMPORTANT NOTICE
Champion Microelectronic Corporation (CMC) reserves the right to make changes to its products or to discontinue any integrated circuit product or service without notice, and advises its customers to obtain the latest version of relevant information to verify, before placing orders, that the information being relied on is current. A few applications using integrated circuit products may involve potential risks of death, personal injury, or severe property or environmental damage. CMC integrated circuit products are not designed, intended, authorized, or warranted to be suitable for Use of CMC products in such applications is In order to minimize risks associated with the customer's applications, the use in life-support applications, devices or systems or other critical applications. understood to be fully at the risk of the customer. customer should provide adequate design and operating safeguards.
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2002/02/05 Preliminary Rev. 1
Champion Microelectronic Corporation
Page 11

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