DATA SHEET AAT3258 300mA LDO Linear Regulator with µP Reset General Description Features The AAT3258 combines a high performance, low noise, 300mA low dropout (LDO) linear regulator with a microprocessor reset monitor. The 300mA output capability of the LDO regulator makes this device ideal for use with microprocessors and DSP cores in portable products. The microprocessor reset monitor section has very low quiescent current consumption and has an active low reset output. The AAT3258 has separate input pins for the reset monitor and LDO regulator so they may be operated from independent sources for increased design flexibility. This device features very low quiescent current, typically less than 71µA. • Integrated LDO Regulator with µP Reset • 300mA Output LDO Regulator • Low Dropout Regulator, 400mV at 300mA • High LDO Output Voltage Accuracy, Typically 1.5% • Very Low Noise and High Power Supply Rejection Ratio (PSRR) LDO • Low Quiescent Current at 71µA • LDO Over-Current/Short-Circuit Protection • LDO Over-Temperature Protection • LDO Power Saving Shutdown Mode • Independent Device Power Inputs • High Accuracy Reset Monitor Threshold: ±1.5% • Active Low Push-Pull Monitor Reset Output • <2.0µA of Shutdown Current • Uses Low Equivalent Series Resistance (ESR) Ceramic Capacitors • -40°C to +85°C Temperature Range • 8-Pin TSOPJW Package The LDO regulator has low dropout voltage, typically 400mV at the full output current level, making it ideal for portable applications where extended battery life is critical. The AAT3258 LDO regulator section has complete over-current/short-circuit and over-temperature protection circuits to guard against extreme operating conditions. The device also has an active output pulldown function when disabled. Applications • Cellular Phones • Digital Cameras • Handheld Instrumentation • Microprocessor/DSP Core/IO Power • Notebook Computers • PDAs and Handheld Computers • Portable Communication Devices The AAT3258 is available in a Pb-free, space-saving 8-pin TSOPJW package. This device is capable of operation over a -40°C to +85°C temperature range. Typical Application 100k VIN VDET VIN RESET RESET OUT VOUT LDO VOUT AAT3258 µP Reset Manual Reset 1µF LDO Shutdown MR GND SHDN BYP 2.2µF 10nF Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202261A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012 1 DATA SHEET AAT3258 300mA LDO Linear Regulator with µP Reset Pin Descriptions Pin # Symbol 1 VIN 2 SHDN 3 VDET 4 MR 5 RESET 6 GND 7 BYP 8 OUT Function LDO voltage regulator input pin. This pin should be decoupled with 1µF or greater capacitor. See application information. LDO voltage regulator shutdown pin. This pin should not be left floating. When connected low, all the internal circuitry is powered down. When high, it is in normal operation. Microprocessor reset input power supply pin. It may be connected to VIN. Manual reset active low input. A logic low signal on MR asserts a reset condition. Asserted reset continues as long as MR is low and for a minimum of 150ms after MR returns high. Reset output remains low while VDET is below the reset threshold and remains so for a minimum of 150ms after VDET rises above the reset threshold. Ground connection pin. LDO voltage regulator bypass capacitor connection. To improve AC ripple rejection and decrease LDO regulator self noise, connect a 10nF ceramic capacitor between this pin and GND. LDO voltage regulator output pin; should be decoupled with a 2.2µF or greater value low ESR ceramic capacitor. Pin Configuration TSOPJW-8 (Top View) 2 VIN 1 8 OUT SHDN 2 7 BYP VDET 3 6 GND MR 4 5 RESET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202261A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012 DATA SHEET AAT3258 300mA LDO Linear Regulator with µP Reset Absolute Maximum Ratings1 TA = 25°C, unless otherwise noted. Symbol VIN VRESET VSHDNIN(MAX) IOUT IRESET DVDET/Dt TJ Description Input Voltage RESET to GND Maximum SHDN to Input Voltage LDO Regulator DC Output Current Maximum Reset Output Current Maximum Rate of VDET Rise Operating Junction Temperature Range Value Units 6.0 -0.3 to VDET + 0.3 0.3 PD/(VIN- VO) 20 100 -40 to 150 V V V mA mA V/µs °C Value Units 150 833 °C/W mW Value Units (VOUT + VDO) to 5.5 1.0 to 5.5 -40 to +85 V V °C Thermal Information2 Symbol Description Maximum Thermal Resistance Maximum Power Dissipation qJA PD Recommended Operating Conditions Symbol VIN VDET T Description Input Voltage to LDO3 Input Voltage to µP Reset (0° to 70°C) Ambient Temperature Range 1. Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at conditions other than the operating conditions specified is not implied. Only one Absolute Maximum Rating should be applied at any one time. 2. Mounted on a demo board. 3. To calculate minimum input voltage, use the following equation: VIN(MIN) = VOUT(MAX) + VDO(MAX) as long as VIN ≥ 2.5V. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202261A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012 3 DATA SHEET AAT3258 300mA LDO Linear Regulator with µP Reset Electrical Characteristics1 TJ = 25°C, unless otherwise noted. Symbol Description Conditions Min Typ Max Units 300mA LDO Regulator TA = 25°C -1.5 1.5 TA = -40°C to 85°C -2.5 300 2.5 Output Voltage IOUT = 1mA to 300mA Output Current Short-Circuit Current Ground Current Shutdown Current Line Regulation VOUT > 1.2V VOUT < 0.4V VIN = 5V, No Load, SHDN = VIN VIN = 5V, SHDN = 0V VIN = VOUT + 1 to 5.0V DVOUT (line) Dynamic Line Regulation IOUT = 300mA, TR/TR = 2µs, VIN = VOUT + 1V to VOUT + 2V 2.5 mV VOUT (load) TENDLY VDO VIL VIH IIL IIH Dynamic Load Regulation Enable Delay Time Dropout Voltage2 Input Low Voltage Input High Voltage Input Low Current Input High Current IOUT = 1mA to 300mA, TR < 5µs BYP = Open IOUT = 300mA 60 15 400 mV µs mV V V µA µA VOUT IOUT ISC IGND ISHDN DVOUT/VOUT*DVIN PSRR TSD THYS eN TC Power Supply Rejection Ratio 600 70 125 1.0 0.09 600 0.6 1.5 1.0 1.0 IOUT = 10mA, CBYP = 10nF 1kHz 10kHz 100kHz 67 47 45 145 12 50 22 Over-Temperature Shutdown Threshold Over-Temperature Shutdown Hysteresis Output Noise Output Voltage Temperature Coefficient % mA mA µA µA %/V dB °C °C µVRMS ppm/°C Microprocessor Reset Monitor VDET IQ Input Voltage Range Quiescent Current TA = 0°C to +70°C TA = -40°C to +85°C 1.05 3.0 0.85 0.85 2.0 2.0 1.0 2.67 2.49 IDD IDOFF Operating Supply Current Reset Leakage Current VTH Reset Threshold Voltage TA = 25°C Reset Threshold Tempco Reset Propagation Delay Reset Active Timeout Period MR Minimum Pulse Width MR Glitch Immunity MR Pull-Up Resistance TMD MR to Reset Propagation Delay VIH VIL MR Input Threshold (high) MR Input Threshold (low) VOL Reset Low Voltage VOH Reset High Voltage 5.5 5.5 VCC = 5.5V VCC = 3.0V VDET = 3.0V VDET > VTH DVTH/°C TP TRDY TMR MRGI RMR 1 1.2 AAT3258xxx-x.x-R AAT3258xxx-x.x-Y 2.59 2.41 VDET = VTH to (VTH - 100mV) 150 10 30 2.63 2.45 40 15 250 400 100 65 90 0.5 VDET = VTH(MAX) VDET = VTH(MAX) ISINK = 1.2mA, VDET = VTH(MIN), VTH ≤ 3.08V, Reset Asserted ISINK = 3.2mA, VDET = VTH(MIN), VTH > 3.08V, Reset Asserted 0.7 · VDET ISOURCE = 800µA, VDET > 3.08V, VDET > VTH(MAX) VDET - 1.5 ISOURCE = 500µA, VDET > VTH(MAX), VTH ≤ 3.08V 0.8 · VDET V µA µA µA V ppm/°C µs ms µs ns kW µs 0.25 · VDET 0.3 0.4 V V V V 1. The AAT3258 is guaranteed to meet performance specifications over the -40°C to 85°C operating temperature range and is assured by design, characterization, and correlation with statistical process controls. 2. VDO is defined as VIN - VOUT when VOUT is 98% of nominal. 4 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202261A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012 DATA SHEET AAT3258 300mA LDO Linear Regulator with µP Reset Typical Characteristics Unless otherwise noted, VIN = 5V, TA = 25°C. Dropout Characteristics Dropout Voltage vs. Temperature 3.20 IL = 300mA 480 Output Voltage (V) Dropout Voltage (mV) 540 420 360 300 IL = 100mA IL = 150mA 240 180 120 60 -40 -30 -20 -10 0 2.80 IOUT = 300mA IOUT = 150mA 2.60 2.40 IOUT = 10mA 2.20 IL = 50mA 0 IOUT = 0mA 3.00 2.00 2.70 10 20 30 40 50 60 70 80 90 100 110 120 Temperature (°C) 2.80 3.00 3.10 3.20 3.30 Ground Current vs. Input Voltage 90.00 500 Ground Current (µA) 450 Dropout Voltage (mV) 2.90 Input Voltage (V) Dropout Voltage vs. Output Current 400 350 300 85°C 250 200 25°C 150 -40°C 100 50 80.00 70.00 60.00 0 50 100 150 200 250 IOUT = 150mA IOUT = 50mA 40.00 IOUT = 0mA 30.00 IOUT = 10mA 20.00 10.00 0.00 300 Output Current (mA) IOUT = 300mA 50.00 0 2 2.5 3 3.5 4 4.5 5 Input Voltage (V) Quiescent Current vs. Temperature Output Voltage vs. Temperature 1.203 100 90 1.202 80 Output Voltage (V) Quiescent Current (µA) IOUT = 100mA IOUT = 50mA 70 60 50 40 30 20 10 0 -40 -30 -20 -10 0 1.200 1.199 1.198 1.197 1.196 -40 -30 -20 -10 10 20 30 40 50 60 70 80 90 100 110 120 Temperature (°C) 1.201 0 10 20 30 40 50 60 70 80 90 100 Temperature (°C) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202261A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012 5 DATA SHEET AAT3258 300mA LDO Linear Regulator with µP Reset Typical Characteristics Unless otherwise noted, VIN = 5V, TA = 25°C. Turn-Off Response Time Initial Power-Up Response Time (CBYP = 10nF) (CBYP = 10nF) VSHDN (5V/div) VSHDN (5V/div) VOUT (1V/div) VOUT (1V/div) Time (400µs/div) Time (50µs/div) Turn-On Time From Enable (VIN present) Line Transient Response (CBYP = 10nF) 6 VSHDN (5V/div) 3.04 Input Voltage (V) 4 3.02 3 3.01 2 3.00 VOUT 1 VIN = 4V VOUT = 1V/div 2.98 Time (100µs/div) Load Transient Response 300mA 500 2.85 400 2.75 200 2.70 2.65 2.60 100 0 IOUT 6 800 2.90 700 2.80 2.70 600 VOUT 500 2.60 400 2.50 300 2.40 2.30 200 IOUT 100 2.20 -100 Time (100µs/div) 3.00 0 2.10 -100 Time (10µs/div) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202261A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012 Output Current (mA) 300 Output Voltage (V) 2.90 Output Current (mA) Output Voltage (V) Load Transient Response 2.80 2.99 0 Time (5µs/div) VOUT 3.03 VIN Output Voltage (V) 5 DATA SHEET AAT3258 300mA LDO Linear Regulator with µP Reset Typical Characteristics Unless otherwise noted, VIN = 5V, TA = 25°C. AAT3258 Self Noise Over-Current Protection 1200 Output Current (mA) Noise Amplitude (µV/rtHz) (COUT = 10µF, ceramic) 10 1 0.1 Band Power: 300Hz to 50kHz = 44.6µVrms/rtHz 100Hz to 100kHz = 56.3µVrms/rtHz 0.01 0.001 0.01 1000 800 600 400 200 0 -200 0.1 1 10 100 1000 Time (20ms/div) 10000 Frequency (kHz) Normalized Reset Threshold vs. Temperature LDO SHDN VIH and V IL vs. VIN 1.250 VIH 1.175 1.150 1.125 VIL 1.100 1.075 1.050 2.5 3.0 3.5 1.003 Normalized Threshold 1.225 1.200 4.0 4.5 5.0 1.002 1.001 1.000 0.999 0.998 0.997 -40 5.5 Reset Propagation Delay (µs) Power-Up Reset Timeout (ms) 300 280 260 240 220 200 180 160 20 40 40 60 80 Power-Down Reset Propagation Delay vs. Temperature 320 0 20 Power-Up Reset Timeout vs. Temperature -20 0 Temperature (°C) Input Voltage (V) -40 -20 60 80 100 Temperature (°C) 30 25 VDO = 10mV 20 15 10 VDO = 100mV 5 0 -40 -20 0 20 40 60 80 Temperature (°C) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202261A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012 7 DATA SHEET AAT3258 300mA LDO Linear Regulator with µP Reset Typical Characteristics Unless otherwise noted, VIN = 5V, TA = 25°C. Maximum Transient Duration vs. Reset Threshold Overdrive Maximum Transient Duration (µs) 400 350 300 250 200 150 100 50 0 1 10 100 Reset Threshold Overdrive, VTH-VCC (mV) 1000 8 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202261A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012 DATA SHEET AAT3258 300mA LDO Linear Regulator with µP Reset Functional Block Diagram OUT VIN Over-Current Protection OverTemperature Protection + Error Amplifier - Voltage Reference BYP SHDN VDET MR + Reset Generator and Timer RESET - Voltage Reference Oscillator GND Functional Description The AAT3258 is intended for LDO regulator applications where output current load requirements range from no load to 300mA. Fast turn-off response time is achieved by an active output pull-down circuit, which is enabled when the LDO regulator is placed in the shutdown mode. This active fast shutdown circuit has no adverse effect on normal device operation. The advanced circuit design of the AAT3258 has been specifically optimized for very fast start-up and shutdown timing. This proprietary CMOS LDO has also been tailored for superior transient response characteristics. These traits are particularly important for applications that require fast power supply timing, such as GSM cellular telephone handsets. The AAT3258 has very fast transient response characteristics, which is an important feature for applications where fast line and load transient response is required. This rapid transient response behavior is accomplished through the implementation of an active error amplifier feedback control. This proprietary circuit design is unique to this MicroPower LDO regulator. The high-speed turn-on capability is enabled through the implementation of a fast start control circuit, which accelerates the power-up behavior of fundamental control and feedback circuits within the LDO regulator. The LDO regulator output has been specifically optimized to function with low-cost, low-ESR ceramic capacitors; however, the design will allow for operation over a wide range of capacitor types. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202261A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012 9 DATA SHEET AAT3258 300mA LDO Linear Regulator with µP Reset A bypass pin has been provided to allow the addition of an optional voltage reference bypass capacitor to reduce output self noise and increase power supply ripple rejection. Device self noise and PSRR will be improved by the addition of a small ceramic capacitor in this pin. However, increased values of CBYPASS may slow down the LDO regulator turn-on time. This LDO regulator has complete short-circuit and thermal protection. The integral combination of these two internal protection circuits gives the AAT3258 a comprehensive safety system to guard against extreme adverse operating conditions. Device power dissipation is limited to the package type and thermal dissipation properties. Refer to the Thermal Considerations section of this datasheet for details on device operation at maximum output current loads. The microprocessor reset section monitors the supply voltage to a microprocessor and asserts a reset signal whenever the VDET voltage falls below a factory-programmed threshold. This threshold is accurate within ±1.5% at 25°C. The reset signal remains asserted for a minimum of 150ms after VDET has risen above the threshold, as shown in Figure 1. LDO Regulator Applications Input Capacitor Typically, a 1µF or larger capacitor is recommended for CIN in most applications. A CIN capacitor is not required for basic LDO regulator operation. However, if the AAT3258 is physically located more than three centimeters from an input power source, a CIN capacitor will be needed for stable operation. CIN should be located as closely to the device VIN pin as practically possible. CIN values greater than 1µF will offer superior input line transient response and will assist in maximizing the highest possible power supply ripple rejection. Ceramic, tantalum, or aluminum electrolytic capacitors may be selected for CIN. There is no specific capacitor ESR requirement for CIN. However, for 300mA LDO regulator output operation, ceramic capacitors are recommended for CIN due to their inherent capability over tantalum capacitors to withstand input current surges from low impedance sources such as batteries in portable devices. To assure the maximum possible performance is obtained from the AAT3258, please refer to the following application recommendations. VTH VTH VTH VDET RESET tRDY tRDY Figure 1: Reset Signal Assertion. 10 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202261A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012 DATA SHEET AAT3258 300mA LDO Linear Regulator with µP Reset Output Capacitor For proper load voltage regulation and operational stability, a capacitor is required between pins VOUT and GND. The COUT capacitor connection to the LDO regulator ground pin should be made as direct as practically possible for maximum device performance. The AAT3258 has been specifically designed to function with very low ESR ceramic capacitors. For best performance, ceramic capacitors are recommended. Typical output capacitor values for maximum output current conditions range from 1µF to 10µF. Applications utilizing the exceptionally low output noise and optimum power supply ripple rejection characteristics of the AAT3258 should use 2.2µF or greater for COUT. If desired, COUT may be increased without limit. In low output current applications where output load is less than 10mA, the minimum value for COUT can be as low as 0.47µF. Bypass Capacitor and Low Noise Applications A bypass capacitor pin is provided to enhance the low noise characteristics of the AAT3258 LDO regulator. The bypass capacitor is not necessary for operation. However, for best device performance, a small ceramic capacitor should be placed between the bypass pin (BYP) and the device ground pin (GND). The value of CBYP may range from 470pF to 10nF. For lowest noise and best possible power supply ripple rejection performance, a 10nF capacitor should be used. To practically realize the highest power supply ripple rejection and lowest output noise performance, it is critical that the capacitor connection between the BYP pin and GND pin be direct and PCB traces should be as short as possible. Refer to the Evaluation Board Layout section of this document for examples. There is a relationship between the bypass capacitor value and the LDO regulator turn-on and turn-off time. In applications where fast device turn-on and turn-off time are desired, the value of CBYP should be reduced. In applications where low noise performance and/ or ripple rejection are less of a concern, the bypass capacitor may be omitted. The fastest device turn-on time will be realized when no bypass capacitor is used. DC leakage on this pin can affect the LDO regulator output noise and voltage regulation performance. For this reason, the use of a low leakage, high quality, ceramic (NPO or C0G type) or film capacitor is highly recommended. Capacitor Characteristics Ceramic composition capacitors are highly recommended over all other types of capacitors. Ceramic capacitors offer many advantages over their tantalum and aluminum electrolytic counterparts. A ceramic capacitor typically has very low ESR, is lower cost, has a smaller PCB footprint, and is non-polarized. Line and load transient response of the LDO regulator is improved by using low ESR ceramic capacitors. Since ceramic capacitors are non-polarized, they are not prone to incorrect connection damage. Equivalent Series Resistance: ESR is a very important characteristic to consider when selecting a capacitor. ESR is the internal series resistance associated with a capacitor that includes lead resistance, internal connections, size and area, material composition, and ambient temperature. Typically, capacitor ESR is measured in milliohms for ceramic capacitors and can range to more than several ohms for tantalum or aluminum electrolytic capacitors. Ceramic Capacitor Materials: Ceramic capacitors less than 0.1µF are typically made from NPO or C0G materials. NPO and C0G materials generally have tight tolerance and are very stable over temperature. Larger capacitor values are usually composed of X7R, X5R, Z5U, or Y5V dielectric materials. These two material types are not recommended for use with LDO regulators since the capacitor tolerance can vary more than ±50% over the operating temperature range of the device. A 2.2µF Y5V capacitor could be reduced to 1µF over temperature; this could cause problems for circuit operation. X7R and X5R dielectrics are much more desirable. The temperature tolerance of X7R dielectric is better than ±15%. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202261A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012 11 DATA SHEET AAT3258 300mA LDO Linear Regulator with µP Reset Capacitor area is another contributor to ESR. Capacitors that are physically large in size will have a lower ESR when compared to a smaller sized capacitor of an equivalent material and capacitance value. These larger devices can improve circuit transient response when compared to an equal value capacitor in a smaller package size. Consult capacitor vendor datasheets carefully when selecting capacitors for LDO regulators. Shutdown Function The shutdown pin is designed to turn off the LDO regulator when the device is not in use. This pin is active high and is compatible with CMOS logic. To assure the LDO regulator will switch on, the SHDN turn-on control level must be greater than 1.5V. The LDO regulator will go into the disable shutdown mode when the voltage falls below 0.6V. If the shutdown function is not needed in a specific application, it may be tied to VIN to keep the LDO regulator in a continuously on state. When the LDO regulator is in the shutdown mode, an internal 1.5kW resistor is connected between VOUT and GND. This is intended to discharge COUT when the LDO regulator is disabled. The internal 1.5kW has no adverse effect on device turn-on time. Short-Circuit Protection The LDO regulator section contains an internal shortcircuit protection circuit that will trigger when the output load current exceeds the internal threshold limit. Under short-circuit conditions, the output of the LDO regulator will be current limited until the short-circuit condition is removed from the output or the LDO regulator package power dissipation exceeds the device thermal limit. Thermal Protection The AAT3258 has an internal thermal protection circuit which will turn on when the device die temperature exceeds 145°C. The internal thermal protection circuit 12 will actively turn off the LDO regulator output pass device to prevent the possibility of over-temperature damage. The LDO regulator output will remain in a shutdown state until the internal die temperature falls back below the 145°C trip point. The combination and interaction between the short-circuit and thermal protection systems allows the LDO regulator to withstand indefinite short-circuit conditions without sustaining permanent damage. No-Load Stability The LDO regulator is designed to maintain output voltage regulation and stability under operational no-load conditions. This is an important characteristic for applications where the output current may drop to zero. Reverse Output-to-Input Voltage Conditions and Protection Under normal operating conditions, a parasitic diode exists between the output and input of the LDO regulator. The input voltage should always remain greater than the output load voltage, maintaining a reverse bias on the internal parasitic diode. Conditions where VOUT might exceed VIN should be avoided since this would forward bias the internal parasitic diode and allow excessive current flow into the VOUT pin, possibly damaging the LDO regulator. In applications where there is a possibility of VOUT exceeding VIN for brief amounts of time during normal operation, the use of a larger value CIN capacitor is highly recommended. A larger value of CIN with respect to COUT will effect a slower CIN decay rate during shutdown, thus preventing VOUT from exceeding VIN. In applications where there is a greater danger of VOUT exceeding VIN for extended periods of time, it is recommended to place a Schottky diode across VIN to VOUT (connecting the cathode to VIN and anode to VOUT). The Schottky diode forward voltage should be less than 0.45V. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202261A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012 DATA SHEET AAT3258 300mA LDO Linear Regulator with µP Reset MicroPower Supervisory Circuit Applications Supply Voltage Transient Behavior Reset Output Options The reset pin is an active low push-pull output. In the event of a power down or brown-out condition, the reset signal remains valid until the VDET drops below 1.2V. Manual Reset Input A logic low signal on MR asserts a reset condition. Reset continues to be asserted as long as MR is low and for a minimum of 150ms after MR returns high. This input is internally pulled up to VCC via a 20kW resistor, so leaving the pin unconnected is acceptable if a manual reset function is not needed. The MR input is internally debounced, which allows use of a mechanical switch. It should be a normally-open momentary switch connected from MR to GND. Additionally, the MR pin can be driven from TTL, CMOS, or open drain logic outputs. In some cases, fast negative transients of short duration can appear on the VCC power supply. The AAT3258 series device provides some immunity to line transients which can generate invalid reset pulses. Figure 2 shows typical behavior of short duration pulses versus RESET comparator overdrive. As shown in the Maximum Transient Duration vs. Reset Threshold Overdrive graph, when the transient voltage becomes larger, the time allowed before asserting a reset becomes shorter (e.g., typically a transient of 100mV below the reset threshold would have to be present for more than 50ms to cause a reset). Immunity can be increased by the addition of a small bypass capacitor of 0.1µF connected as closely to the VCC pin as possible. Evaluation Board Layout The AAT3258 evaluation layout (Figures 3, 4, and 5) follows the recommend printed circuit board layout procedures and can be used as an example for good application layouts. Note: Board layout shown is not to scale. VCC VCC VDET 0.1µF RESET MR GND RESET µP INPUT GND Figure 2: Typical Behavior of Short Duration Pulses vs. RESET Comparator Overdrive. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202261A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012 13 DATA SHEET AAT3258 300mA LDO Linear Regulator with µP Reset Figure 3: Evaluation Board Component Side Layout. Figure 4: Evaluation Board Solder Side Layout. Figure 5: Evaluation Board Top Side Silk Screen Layout / Assembly Drawing. 14 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202261A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012 DATA SHEET AAT3258 300mA LDO Linear Regulator with µP Reset Ordering Information Package Reset Threshold Voltage1 LDO Regulator Marking2 Part Number (Tape and Reel)3 TSOPJW-8 TSOPJW-8 TSOPJW-8 TSOPJW-8 2.63V 2.45V 2.63V 2.63V 2.80V 2.80V 3.0V 3.3V IIXYY IHXYY MEXYY MXXYY AAT3258ITS-2.8-R-T1 AAT3258ITS-2.8-Y-T1 AAT3258ITS-3.0-R-T1 AAT3258ITS-3.3-R-T1 Skyworks Green™ products are compliant with all applicable legislation and are halogen-free. For additional information, refer to Skyworks Definition of Green™, document number SQ04-0074. Package Information TSOPJW-8 2.85 – 0.20 2.40 – 0.10 0.325 – 0.075 0.65 BSC 0.65 BSC 0.65 BSC 7 0.055 – 0.045 0.04 REF 0.15 – 0.05 1.0175 – 0.0925 0.9625 – 0.0375 3.025 – 0.075 0.010 0.45 – 0.15 2.75 – 0.25 All dimensions in millimeters. 1. Consult the factory for any additional reset or low dropout voltages. 2. XYY = assembly and date code. 3. Sample stock is generally held on part numbers listed in BOLD. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202261A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012 15 DATA SHEET AAT3258 300mA LDO Linear Regulator with µP Reset Copyright © 2012 Skyworks Solutions, Inc. All Rights Reserved. Information in this document is provided in connection with Skyworks Solutions, Inc. (“Skyworks”) products or services. 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