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www.fairchildsemi.com
FAN2508, FAN2509
50 mA CMOS LDO Regulators
Features
* * * * * * * Ultra Low Power Consumption 50 mV dropout voltage at 50 mA 25 A ground current at 50 mA Enable/Shutdown Control SOT23-5 package Thermal limiting 300 mA peak current
wide variety of external capacitors, and the compact SOT23-5 surface-mount package. The FAN2508/09 family of products offer significant improvements over older BiCMOS designs and are pin-compatible with many popular devices. The output is thermally protected against overload. The FAN2508 and FAN2509 devices are distinguished by the assignment of pin 4: FAN2508: pin 4 - ADJ, allowing the user to adjust the output voltage over a wide range using an external voltage divider. FAN2508-XX: pin 4 - BYP, to which a bypass capacitor may be connected for optimal noise performance. Output voltage is fixed, indicated by the suffix XX. FAN2509-XX: pin 4 - ERR, a flag which indicates that the output voltage has dropped below the specified minimum due to a fault condition. The standard fixed output voltages available are 2.5V, 2.6V, 2.7V, 2.8V, 2.85V, 3.0V, and 3.3V. Custom output voltage are also available: please contact your local Fairchild Sales Office for information.
Applications
* * * * Cellular Phones and accessories PDAs Portable cameras and video recorders Laptop, notebook and palmtop computers
Description
The FAN2508/09 family of micropower low-dropout voltage regulators utilize CMOS technology to offer a new level of cost-effective performance in GSM and TDMA cellular handsets, Laptop and Notebook portable computers, and other portable devices. Features include extremely low power consumption and low shutdown current, low dropout voltage, exceptional loop stability able to accommodate a
Block Diagrams
EN VIN Bandgap Error Amplifier p VOUT ADJ Thermal Sense FAN2508 GND FAN2508-XX EN VIN Bandgap p VOUT ERR Error Amplifier Thermal Sense VIN Bandgap p VOUT EN BYP Error Amplifier
GND
Thermal Sense FAN2509-XX
GND
REV. 1.0.6 2/14/03
PRODUCT SPECIFICATION
FAN2508/FAN2509
Pin Assignments
VIN GND EN
1 5
VOUT
2
3
4
ADJ/BYP/ERR
Pin No. 1. 2. 3. 4. 5.
FAN2508 VIN GND EN ADJ VOUT
FAN2508-XX VIN GND EN BYP VOUT
FAN2509-XX VIN GND EN ERR VOUT
Pin Descriptions
Pin Name ADJ BYP ERR Pin No. 4 4 4 Type Input Passive Open drain Pin Function Description FAN2508 Adjust. Ratio of potential divider from VOUT to ADJ determines output voltage. FAN2508-XX Bypass. Connect 470 pF capacitor for noise reduction. FAN2509-XX Error. Error flag output. 0: Output voltage < 95% of nominal. 1: Output voltage > 95% of nominal. Enable. 0: Shutdown VOUT. 1: Enable VOUT. Voltage Input. Supply voltage input. Voltage Output. Regulated output voltage. Ground.
EN
3
Digital Input
VIN VOUT GND
1 5 2
Power in Power out Power
Functional Description
Designed utilizing CMOS process technology, the FAN2508/09 family of products are carefully optimized for use in compact battery-powered devices, offering a unique combination of low power consumption, extremely low dropout voltages, high tolerance for a variety of output capacitors, and the ability to disable the output to less than 1A under user control. In the circuit, a difference amplifier controls the current through a series-pass P-Channel MOSFET, comparing the load voltage at the output with an onboard low-drift bandgap reference. The series resistance of the pass P-Channel MOSFET is approximately 1, resulting in an unusually low dropout voltage under load when compared to older bipolar pass-transistor designs. Protection circuitry is provided onboard for overload conditions. In conditions where the device reaches temperatures exceeding the specified maximums, an onboard circuit shuts down the output, where it remains suspended until it has cooled before re-enabling. The user is also free to shut down the device using the Enable control pin at any time. Careful design of the output regulator amplifier assures loop stability over a wide range of ESR values in the external output capacitor. A wide range of values and types can be accomodated, allowing the user to select a capacitor meeting his space, cost, and performance requirements, and enjoy reliable operation over temperature, load, and tolerance variations.
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FAN2508/FAN2509
PRODUCT SPECIFICATION
Depending on the model selected, a number of control and status functions are available to enhance the operation of the LDO regulator. An Enable pin, available on all devices, allows the user to shut down the regulator output to conserve power, reducing supply current to less than 1A. The adjustable-voltage versions of the device utilize pin 4 to connect to an external voltage divider which feeds back to the regulator error amplifier, thereby setting the voltage as desired. Two other functions are available at pin 4 in the fixed-voltage versions: in noise-sensitive applications, an external Bypass capacitor connection is provided that allows the user to achieve optimal noise performance at the output, while the Error output functions as a diagnostic flag to indicate that the output voltage has dropped more than 5% below the nominal fixed voltage.
Bypass Capacitor (FAN2508 Only)
In the fixed-voltage configuration, connecting a capacitor between the bypass pin and ground can significantly reduce noise on the output. Values ranging from 470pF to 10nF can be used, depending on the sensitivity to output noise in the application. At the high-impedance Bypass pin, care must be taken in the circuit layout to minimize noise pickup, and capacitors must be selected to minimize current loading (leakage). Noise pickup from external sources can be considerable. Leakage currents into the Bypass pin will directly affect regulator accuracy and should be kept as low as possible; thus, highquality ceramic and film types are recommended for their low leakage characteristics. Cost-sensitive applications not concerned with noise can omit this capacitor.
Applications Information
Control Functions External Capacitors - Selection
The FAN2508/09 allows the user to utilize a wide variety of capacitors compared to other LDO products. An innovative design approach offers significantly reduced sensitivity to ESR (Effective Series Resistance), which degrades regulator loop stability in older designs. While the improvements featured in the FAN2508/09 family greatly simplify the design task, capacitor quality still must be considered if the designer is to achieve optimal circuit performance. In general, ceramic capacitors offer superior ESR performance, at a lower cost and a smaller case size than tantalums. Those with X7R or Y5Vdielectric offer the best temperature coefficient characteristics. The combination of tolerance and variation over temperature in some capacitor types can result in significant variations, resulting in unstable performance over rated conditions. Enable Pin Applying a voltage of 0.4V or less at the Enable pin will disable the output, reducing the quiescent output current to less than 1A, while a voltage of 2.0V or greater will enable the device. If this shutdown function is not needed, the pin can simply be connected to the VIN pin. Allowing this pin to float will cause erratic operation. Error Flag (FAN2509 only) To indicate conditions such as input voltage dropout (low VIN), overheating, or overloading (excessive output current), the ERR pin indicates a fault condition. It is an opendrain output which is HIGH when the voltage at VOUT is greater than 95% of the nominal rated output voltage and LOW when VOUT is less than 95% or the rated output voltage, as specified in the error trip level characteristics. A logic pullup resistor of 100K is recommended at this output. The pin can be left disconnected if unused. Thermal Protection The FAN2508/09 is designed to supply high peak output currents of up to 1A for brief periods, however this output load will cause the device temperature to increase and exceed maximum ratings due to power dissipation. During output overload conditions, when the die temperature exceeds the shutdown limit temperature of 150C, onboard thermal protection will disable the output until the temperature drops below this limit, at which point the output is then re-enabled. During a thermal shutdown situation the user may assert the power-down function at the Enable pin, reducing power consumption to the minimum level IGND * VIN.
Input Capacitor
An input capacitor of 2.2F (nominal value) or greater, connected between the Input pin and Ground, located in close proximity to the device, will improve transient response and noise rejection. Higher values will offer superior input ripple rejection and transient response. An input capacitor is recommended when the input source, either a battery or a regulated AC voltage, is located far from the device. Any good quality ceramic, tantalum, or metal film capacitor will give acceptable performance, however tantalum capacitors with a surge current rating appropriate to the application must be selected to avoid catastrophic failure.
Output Capacitor
An output capacitor is required to maintain regulator loop stability. Unlike many other LDO regulators, the FAN2508/09 family of products are nearly insensitve to output capacitor ESR. Stable operation will be achieved with a wide variety of capacitors with ESR values ranging from 10m to 10 or more. Tantalum or aluminum electrolytic, or multilayer ceramic types can all be used. A nominal value of at least 1F is recommended.
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3
PRODUCT SPECIFICATION
FAN2508/FAN2509
Thermal Characteristics
The FAN2508/09 is designed to supply 50mA at the specified output voltage with an operating die (junction) temperature of up to 125C. Once the power dissipation and thermal resistance is known, the maximum junction temperature of the device can be calculated. While the power dissipation is calculated from known electrical parameters, the thermal resistance is a result of the thermal characteristics of the compact SOT23-5 surface-mount package and the surrounding PC Board copper to which it is mounted. The power dissipation is equal to the product of the input-tooutput voltage differential and the output current plus the ground current multiplied by the input voltage, or:
P D = ( V IN - V OUT )I OUT + V IN I GND
the device to enter a thermal cycling loop, in which the circuit enters a shutdown condition, cools, re-enables, and then again overheats and shuts down repeatedly due to an unmanaged fault condition.
Operation of Adjustable Version
The adjustable version of the FAN2508/09 includes an input pin ADJ which allows the user to select an output voltage ranging from 1.8V to near VIN, using an external resistor divider. The voltage VADJ presented to the ADJ pin is fed to the onboard error amplifier which adjusts the output voltage until VADJ is equal to the onboard bandgap reference voltage of 1.32V(typ). The equation is:
R upper V OUT = 1.32V x 1 + --------------R lower
The ground pin current IGND can be found in the charts provided in the Electrical Characteristics section. The relationship describing the thermal behavior of the package is:
T J ( max ) - T A P D ( max ) = ------------------------------- JA
The total value of the resistor chain should not exceed 250K total to keep the error amplifier biased during no-load conditions. Programming output voltages very near VIN need to allow for the magnitude and variation of the dropout voltage VDO over load, supply, and temperature variations. Note that the low-leakage FET input to the CMOS Error Amplifier induces no bias current error to the calculation.
where TJ(max) is the maximum allowable junction temperature of the die, which is 125C, and TA is the ambient operating temperature. JA is dependent on the surrounding PC board layout and can be empirically obtained. While the JC (junction-to-case) of the SOT23-5 package is specified at 130C /W, the JA of the minimum PWB footprint will be at least 235C /W. This can be improved upon by providing a heat sink of surrounding copper ground on the PWB. Depending on the size of the copper area, the resulting JA can range from approximately 180C /W for one square inch to nearly 130C /W for 4 square inches. The addition of backside copper with through-holes, stiffeners, and other enhancements can also aid in reducing this value. The heat contributed by the dissipation of other devices located nearby must be included in design considerations. Once the limiting parameters in these two relationships have been determined, the design can be modified to ensure that the device remains within specified operating conditions. If overload conditions are not considered, it is possible for
General PWB Layout Considerations
To achieve the full performance of the device, careful circuit layout and grounding technique must be observed. Establishing a small local ground, to which the GND pin, the output and bypass capacitors are connected, is recommended, while the input capacitor should be grounded to the main ground plane. The quiet local ground is then routed back to the main ground plane using feedthrough vias. In general, the highfrequency compensation components (input, bypass, and output capacitors) should be located as close to the device as possible. The proximity of the output capacitor is especially important to achieve optimal noise compensation from the onboard error amplifier, especially during high load conditions. A large copper area in the local ground will provide the heat sinking discussed above when high power dissipation significantly increases the temperature of the device. Component-side copper provides significantly better thermal performance for this surface-mount device, compared to that obtained when using only copper planes on the underside.
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FAN2508/FAN2509
PRODUCT SPECIFICATION
Absolute Maximum Ratings (beyond which the device may be damaged)1
Parameter Power Supply Voltages VIN (Measured to GND) Enable Input (EN) Applied voltage (Measured to GND)2 ERR Output Applied voltage (Measured to GND)2 Power Dissipation3 Temperature Junction Lead Soldering (5 seconds) Storage Electrostatic Discharge
4
Min 0 0 0
Typ
Max 7 7 7
Unit V V V
Internally limited -65 -65 4 150 260 150 C C C kV
Notes: 1. Functional operation under any of these conditions is NOT implied. Performance and reliability are guaranteed only if Operating Conditions are not exceeded. 2. Applied voltage must be current limited to specified range. 3. Based upon thermally limited junction temperature: T J ( max ) - T A P D = ------------------------------ JA 4. Human Body Model is 4kV minimum using Mil Std. 883E, method 3015.7. Machine Model is 400V minimum using JEDEC method A115-A.
Recommended Operating Conditions
Parameter VIN VOUT VEN VERR TJ JA JC Input Voltage Range Output Voltage Range, Adjustable Enable Input Voltage ERR Flag Voltage Junction Temperature Thermal resistance Thermal resistance -40 220 130 Min 2.7 VREF 0 Nom Max 6.5 VIN-VDO VIN VIN +125 Units V V V V C C/W C/W
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PRODUCT SPECIFICATION
FAN2508/FAN2509
Electrical Characteristics (Notes 1, 2)
Symbol Regulator VDO VO VDO VO3 IGND Protection Current Limit IGSD TSH ETL VIL VIH IIH II Shut-Down Current Thermal Protection Shutdown Temperature ERR Trip Level Logic Low Voltage Logic High Voltage Input Current High Input Current Low 2.0 FAN2509 only EN = 0V 150 90 95 1.2 1.4 1 1 99 0.4 Thermally Protected 1 A C % V V A A Drop Out Voltage Output Voltage Accuracy Reference Voltage Accuracy, Adjustable Mode Output Voltage Accuracy, Adjustable Mode Ground Pin Current IOUT = 50 mA IOUT = 100 A IOUT = 50 mA -2 1.24 -6 1.32 2.5 50 4 75 2 1.40 6 50 mV mV % V % A Parameter Conditions Min. Typ. Max. Units
Enable Input
Switching Characteristics (Notes 1, 2)
Parameter Enable Input Response time Error Flag (FAN2509-XX) Response time 3 msec 500 sec Conditions Min. Typ. Max. Unit
Performance Characteristics (Notes 1, 2)
Symbol VOUT/VIN VOUT/VOUT eN Parameter Line regulation Load regulation Output noise Conditions VIN = (VOUT + 1) to 6.5V IOUT = 0.1 to 50mA 10Hz-1KHz COUT = 10F, CBYP = 0.01F >10KHz, COUT = 10F, CBYP = 0.01F PSRR Power Supply Rejection 120 Hz, COUT = 10F, CBYP = 0.01F Min. Typ. 0.3 1.0 <7 2.0 Max. Units % /V %
V/ Hz
<0.01 43 dB
Notes: 1. Unless otherwise stated, TA = 25C, VIN = VOUT + 1V, IOUT = 100A, VIH > 2.0 V. 2. Bold values indicate -40 TJ 125C. 3. The adjustable version, has a bandgap voltage range of 1.24V to 1.40V with a nominal value of 1.32V. 4. When using repeated cycling.
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FAN2508/FAN2509
PRODUCT SPECIFICATION
Typical Performance Characteristics
Power Supply Rejection Ratio
100 IOUT = 100A 80 COUT = 1.0F Cer.
PSRR (dB) PSRR (dB)
Power Supply Rejection Ratio
100 VIN = 4.0V IOUT = 10mA 80 VOUT = 3.0V COUT = 1.0F Cer. 60 40 20 0 10 100
PSRR (dB)
Power Supply Rejection Ratio
100 VIN = 4.0V IOUT = 50mA 80 VOUT = 3.0V COUT = 1.0F Cer. 60 40 20 0 10 100
60 40 20 0 10 VIN = 4.0V VOUT = 3.0V 100 1k 10k 100k 1M 10M Frequency (Hz)
1k 10k 100k 1M 10M Frequency (Hz)
1k 10k 100k 1M 10M Frequency (Hz)
Power Supply Rejection Ratio
100 VIN = 4.0V 80 VOUT = 3.0V
PSRR (dB) PSRR (dB)
Power Supply Rejection Ratio
100 VIN = 4.0V 80 VOUT = 3.0V 60 40 20 0 10 100 100
Power Supply Rejection Ratio
IOUT = 50mA 80 COUT = 10F Cer.
PSRR (dB)
60 40 20 0 10 100 IOUT = 100A COUT = 10F Cer. 1k 10k 100k 1M 10M Frequency (Hz)
IOUT = 10mA COUT = 10F Cer.
60 40 20 0 10
VIN = 4.0V VOUT = 3.0V
1k 10k 100k 1M 10M Frequency (Hz)
100
1k 10k 100k 1M 10M Frequency (Hz)
Power Supply Rejection Ratio vs. Voltage Drop
70 60
PSRR (dB)
Power Supply Rejection Ratio vs. Voltage Drop
70 60
PSRR (dB)
Noise Performance
10 1
Noise (V/ Hz)
50 40 30 20 10 0 3.0
IOUT = 100A
10mA
50 40 30 20 10
IOUT = 100A
VIN = 4.0V VOUT = 3.0V
0.1 0.01 COUT = 1.0F CBYP = 0.01F I L = 10A 100 1k 10k 100k Frequency (Hz) 1M
50mA
COUT = 1.0F Cer.
10mA
0.001
50mA 3.0 3.6 Voltage (V) COUT = 10F Cer. 4.1
3.6 Voltage (V)
4.1
0
0.0001 10
Ground Pin Current
25.00
Quiescent Current (A)
Ground Pin Current
35.00
Quiescent Current (A)
Ground Pin Current
35.00 30.00 25.00 20.00 15.00 10.00 5.00 0.00 3.0 4.0 5.0 VOUT = 3V IOUT = 50mA 6.0 7.0
Quiescent Current (A)
23.00 21.00 19.00 17.00 15.00 0.1
VIN = 4V VOUT = 3V
30.00 25.00 20.00 15.00 10.00 5.00 0.00 3.0 VOUT = 3V IOUT = 100A 4.0 5.0 6.0 Input Voltage (V) 7.0
10 1 Load Current (mA)
Input Voltage (V)
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PRODUCT SPECIFICATION
FAN2508/FAN2509
Typical Performance Characteristics (continued)
Ground Pin Current
75 Quiescent Current (A) Quiescent Current (A) VIN = 4V VOUT = 3V IL = 100A 75 Dropout Voltage (mV) VIN = 4V VOUT = 3V IL = 50mA
Ground Pin Current
50.00 40.00 30.00 20.00 10.00 0.00 0.1
Dropout Voltage
50
50
25
25
0 -40
0
40 80 Temperature (C)
125
0 -40
0
40 80 Temperature (C)
125
10
20
30
40
50
Output Current (mA)
Dropout Characteristics
3.5 3.0 VOUT = 3V Dropout Voltage (mV) Output Voltage (V) ROUT = 30K 2.0 ROUT = 20 1.5 1.0 0.5 0.0 0.0 1.0 2.0 3.0 4.0 5.0 6 Dropout Voltage (mV) 2.5 75 8
Dropout Voltage
100
Dropout Voltage
4 IL = 100A
50 IL = 50mA
2
25
0 -40
Input Voltage (V)
0 40 80 Temperature (C)
125
0 -40
0 40 80 Temperature (C)
125
Output Voltage vs. Temperature
3.05
Output Voltage (V)
3
2.95 VIN = 4V Typical 3V device IL = 100A 0 40 80 Temperature (C) 125
2.9
2.85 -40
Functional Characteristics
Enable Pin Delay
Enable Disable Voltage (1V/div) Enable Voltage (1V/div)
Shutdown Delay
Disable
VOUT Output Voltage (1V/div) Output Voltage (1V/div) VOUT
Time (20s/div)
Time (20s/div)
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REV. 1.0.6 2/14/03
FAN2508/FAN2509
PRODUCT SPECIFICATION
Mechanical Dimensions
5-Lead SOT-23-5 (S) Package
Symbol A A1 B c D E e e1 H L
Inches Min. .035 .000 .008 .003 .106 .059 Max. .057 .006 .020 .010 .122 .071
Millimeters Min. .90 .00 .20 .08 2.70 1.50 Max. 1.45 .15 .50 .25 3.10 1.80
Notes: Notes 1. Package outline exclusive of mold flash & metal burr. 2. Package outline exclusive of solder plating. 3. EIAJ Ref Number SC-74A.
.037 BSC .075 BSC .087 .126 .004 .024 0 10
.95 BSC 1.90 BSC 2.20 3.20 .10 .60 0 10
B
e L
E
H
e1 D
c
A
A1
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PRODUCT SPECIFICATION
FAN2508/FAN2509
Ordering Information
Product Number FAN2508SX FAN2508S25X FAN2508S26X FAN2508S27X FAN2508S28X FAN2508S285X FAN2508S30X FAN2508S33X FAN2509S25X FAN2509S26X FAN2509S27X FAN2509S28X FAN2509S285X FAN2509S30X FAN2509S33X VOUT Adj. 2.5 2.6 2.7 2.8 2.85 3.0 3.3 2.5 2.6 2.7 2.8 2.85 3.0 3.3 Pin 4 Function Adjust Bypass Bypass Bypass Bypass Bypass Bypass Bypass Error output Error output Error output Error output Error output Error output Error output Package Marking AAA AAE AAG AAJ AAM AAN AAW AA3 ABE ABG ABJ ABM ABN ABW AB3
Tape and Reel Information
Quantity 3000 Reel Size 7" Width 8mm
DISCLAIMER FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. FAIRCHILD DOES NOT ASSUME ANY LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN; NEITHER DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS. LIFE SUPPORT POLICY FAIRCHILD'S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and (c) whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury of the user. www.fairchildsemi.com
2/14/03 0.0m 005 Stock#DS30002508 2000 Fairchild Semiconductor Corporation
2. A critical component in any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness.

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