AMS3108 Micropower 700mA Low Noise Fast Transient Response LDO General Description Features The AMS3108 is a high performance linear regulator with very low dropout voltage and excellent transient response. It is designed to operate with wide input voltage range of 1.5 – 12Volts making it ideal for two step conversion while maintaining high efficiency for many power sensitive applications. The device is capable of supplying 700mA of output current with a typical dropout voltage of 550mV. The product is available in either fixed or adjustable output voltage. The linear regulator has been optimized for noise sensitive applications. The device includes an Enable pin for electrical on/off of the regulator. Forcing the Enable pin to logic low shuts down the LDO and reduces the supply current below 1µA. In addition, the AMS3108 provides an open collector Power Good (PG) signal to allow supply monitoring and sequencing of other supplies. The product includes complete short-circuit and thermal protection. The combination of these two internal protection circuits gives the device a comprehensive safety system to safe guard against extreme adverse operating conditions. The AMS3108 is available in a thermally enhanced SOIC-8 EDP package, and it is rated for -40°C to +125°C temperature range. • • • • • • • • • • • • • • • • VIN range: 1.5 – 12V Fixed and Adjustable output voltage as low as 0.6V 700mA maximum output current 550mV of typical dropout voltage at 700mA Low self noise Enable (EN) pin for LDO on/off Power Good (PG) output 120µA typical supply current ByPass pin (CBYP) for low PSRR and output noise PSRR > 40dB at 10KHz Stable with Electrolytic, Tantalum or Ceramic capacitors Current Limit protection Over-Temperature Shutdown -40 to +125°C temperature range Thermally enhanced SOIC-8 exposed paddle package RoHS & WEEE compliant Applications • • • • • • • • ASIC Power Supplies In: ¾ Set-top Boxes, Desktops, Notebooks ¾ Graphic Cards, Printers and Copiers DVD, Blue-Ray DVD writers LCD TVs and LCD monitors Infotainment Wireless & RF: applications DSP and FPGA Power Supplies Medical Instrumentation SMPS Post-Regulator Typical Application 02/11/2010 www.advanced-monolithic.com 1 Phone (925) 443-0722 Fax (925) 443-0723 AMS3108 Micropower 700mA Low Noise Fast Transient Response LDO Pin Description (SOIC-8 EDP package) Pin # Symbol 1 BYP Reference Bypass pin. Connect an external capacitor from CBYP to ground to bypass the noise generated by the internal bandgap. This improves power supply rejection ratio and output noise. 2 GND Ground 3 GND Ground 4 VIN 5 VOUT Output Voltage ADJ Provides feedback to error amplifier from the resistive divider that sets the output voltage. NC No Connection 7 PG Power Good pin. It is an open collector, active high output that indicates the status of the output voltage. When output voltage (VOUT) exceeds the PG trip threshold, the PG pin goes in to a high impedance state. When the device is out of regulation or shutdown, the PG pin is pulled low. A 10KΩ to 1MΩ resistor should be connected from PG to VOUT. 8 EN Enable pin. It controls the electrical on/off of the device. When connected to logic low, the device shuts off and consumes less than 1µA of current. Logic high will resume normal operation. 9 GND 6 Description Input supply Voltage. It powers the internal control circuitry and the internal power switch. Bypass VIN with at ceramic capacitor from this pin to ground. Expose pad. Connected to PCB ground plane for good thermal dissipation. Pin Configuration SOIC-8 EDP (Top View) BYP 1 GND 2 GND 3 VIN 02/11/2010 4 8 EN 9 GND 7 PG 6 ADJ / NC 5 VOUT www.advanced-monolithic.com 2 Phone (925) 443-0722 Fax (925) 443-0723 AMS3108 Micropower 700mA Low Noise Fast Transient Response LDO Absolute Maximum Ratings (1) Recommended Operating Conditions (2) Maximum Input Supply Voltage (VIN)………....……..… -0.3V to 15V Enable Voltage (EN)……………..…..………….……… -0.3V to 15V Power Good (PG).……………..…..………………….… -0.3V to 15V Adjustable Voltage (ADJ)……………………………….… -0.3V to 3V ByPass Voltage (BYP)…………..…..…………………… -0.3V to 3V Storage Temperature Range……………................. -65⁰C to 150⁰C Lead Temperature…………………..………….…………..…… 260⁰C Junction Temperature………...………………..……..………… 125⁰C Input Voltage………………………………….……..…….. 1.5V to 12V Ambient Operating Temperature…………….……… -40⁰C to 125⁰C Thermal Information 8L SOIC EP θJA (3) ………………………………………..…...45⁰C/W Electrical Characteristics Unless otherwise noted: VIN=3.3V, VOUT=1.8V; CIN=10 µF, COUT=22µF, -40⁰C≤TA=TJ≤85⁰C, TJ(Max.)=125°C; Typical values are TA=25°C Parameter Symbol Conditions Output Voltage Accuracy VOUT Adjustable Voltage VADJ Adjustable VOUT only IADJ_Bias IOUT_Max Adjustable VOUT only Adjustable bias current Maximum Output Current Load Regulation Line Regulation Supply Current Shutdown Current Current Limit Dropout Voltage ISUP ISHDN ILIM Output Noise Voltage Typ. Max. Units 3 % 0.6 0.606 V 10 100 nA mA -3 0.594 700 IOUT= 0 – 700mA 0.6 VIN=3.0 – 12V; IOUT=100mA 0.15 VIN=3.3V, Io=0A VIN=3.3V, VEN=0V 120 <1 800 IOUT=100mA; VOUT=95% of VOUT(NOM) 220 IOUT=250mA; VOUT=95% of VOUT(NOM) 300 IOUT=500mA; VOUT=95% of VOUT(NOM) 425 IOUT=750mA; VOUT=95% of VOUT(NOM) 600 F=10KHz Io=20mA 33 % % 150 VDO ΔVOUT/ΔVIN PSRR Min. en µA µA mA mV BW: 100Hz–100 KHz COUT = 22µF ILOAD = 150mA No CBYP 118 CBYP = 10nF 33 dB µV(rms) Enable Threshold Low Enable Threshold High Input Enable Low Current Input Enable High Current Power Good Low Threshold Power Good High Threshold VEN(L) VEN(H) IEN(L) IEN(H) VPG VPG VEN = 0V VEN = 1.5V % of VOUT PG ON % of VOUT PG OFF Power Good Output Low Voltage VPGL IPG_SINK = 500μA,Fault Condition 200 PG off, VPG = 12V 0.01 μA 145 15 °C °C Power Good Leakage Current IPG Thermal Shutdown Thermal Shutdown Hysteresis TSD TSD_HYS Notes: 1. 2. 3. 1 1.1 0 150 97 V V nA nA % % 300 mV 10 300 89 Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Measured on approximately 1” square of 1 oz. copper. The total power dissipation for SO-8 EDP package is recommended to 2.5W rated at 25⁰C ambient temperature. The thermal resistance Junction to Case is 45⁰C/W. Total power dissipation for the switching regulator and the LDO should be taken in consideration when calculating the output current capability of each regulator. 02/11/2010 www.advanced-monolithic.com 3 Phone (925) 443-0722 Fax (925) 443-0723 A AMS3 3108 Micrropower 70 00mA Low w Noise Fas st Transien nt Respons se LDO Outputt Voltage Tem mperature Va ariation (Fixe ed Voltage Option) O VO = 1.8V 1.825 Adjustable (ADJ J) Voltage Te emperature Variation (Adju ustable Voltage Option) 0.606 Output Voltage (V) Adjust Voltage (V) Ty ypical Perfo ormance Characteris C stics (TA = 25°C 2 unless otherwise o sp pecified) 0.604 0.602 1.815 1.805 1.795 0.600 -25 -50 0 25 50 7 75 -50 100 12 25 -25 Ambient Temperature e (ºC) ‐ ‐50°C 20 25°C 15 10 5 100°C 0 100 0 200 30 00 400 50 00 600 30 20 25°C 10 0 0 70 00 1 Output Voltage Change (%) Output Voltage Error (%) 0.1 0.0 -0.1 -0.2 3 4 5 6 7 8 9 10 11 12 12 2 Load Re egulation 0.2 0 -0.2 -0.4 -0.6 0.0 Input Voltage (V) 02/11/2010 0 2 oltage (V) Input Vo 0.2 9 100 125 125°C 40 Line Regulation VO = 1.8V, IO = 100mA 6 75 50 Outpu ut Current (A A) 3 50 Shutd down Current vs. Input Voltage IGND vs s. Output Currrent VO=1.8V V, Vin=2.5V 25 25 5 Ambient Te emperature (ºC) ( Shutdown Current (µA) Ground Current (mA) 30 0 www.ad dvanced-mono olithic.com 4 0.1 0 Output Current C (A) 1.0 Phone (925)) 443-0722 Fax (925)) 443-0723 A AMS3 3108 Micrropower 70 00mA Low w Noise Fas st Transien nt Respons se LDO Ty ypical Perfo ormance Characteris C stics (TA = 25°C 2 unless otherwise o sp pecified) Dropout p Voltage g (mV) ( ) 600 500 400 100°C 25°C 300 ‐50°C 200 100 VOUT = 1.8V Dropout Voltage (mV) VDO vs. Ou utput Curren nt 700 VDO vs. Tempera ature (IO = 70 00mA) 7 700 6 600 5 500 4 400 3 300 2 200 0 0 10 00 200 30 00 400 50 00 600 Outpu ut Current (m mA) 700 0 25 50 75 -25 Ambient Tem mperature (°C) 100 Enable Starrt-Up Load Transient 50mA to 550mA A, VOUT=1.8V, VIN=3.3V CIN= COUT=4.7µF 02/11/2010 0 -50 IOUT = 0 to 350mA, VOUT = 1.8V, VIN = 3.0V, CIN=C = OUT=10µF www.ad dvanced-mono olithic.com 5 Phone (925)) 443-0722 Fax (925)) 443-0723 AMS3108 Micropower 700mA Low Noise Fast Transient Response LDO Functional Block Diagram VOUT VIN Over Current Protection R1 *Note* - ADJ Error Amp EN + R2 Power Good Comparator Over Temperature Protection PG - BYP + VREF= 0.6V *Note*: Resistors R1 and R2 are integrated into the part for the Fixed-Voltage option. GND Figure 1: Block Diagram of AMS 3108 02/11/2010 www.advanced-monolithic.com 6 Phone (925) 443-0722 Fax (925) 443-0723 AMS3108 Micropower 700mA Low Noise Fast Transient Response LDO Device Summary The AMS3108 is a high voltage low drop out linear regulator with a current capability of up to 700mA. The LDO has an input voltage range of 1.5V to 12V with an output voltage as low as 0.6V and is stable with a wide range of ceramic, tantalum, and electrolytic output capacitors. Shutdown/Enable The Enable (on/off) input threshold voltage is 1.1V. When disabled the LDO quiescent current decreases to a typical value of <1µA. Fault Protection Short circuit and over-temperature shutdown disable the converter and LDO in the event of an overload condition. Overtemp shutdown disables the device when the junction temperature exceeds 145 ºC. The output current is internally limited to 800mA. Input Capacitor An input bypass capacitor ranging from 1µF to 10µF is required. The capacitor should be placed as close as possible to the device and not be placed more than 1 inch from the LDO. Output Capacitor The output capacitor requirements range from the minimum value required to guarantee stability to larger values required to meet the extreme transient response requirements. Values range from 10 to 22µF X5R ceramic capacitors. Due to the extreme voltage coefficient of X5R ceramic capacitors, the voltage rating should be at least double the maximum applied voltage. Bypass Capacitor If the ByPass (BYP) is available, connecting a capacitor between the BYP pin and ground can significantly reduce output noise. Values can range from 0pF to 10nF, depending on the sensitivity to output noise in the application. The start-up speed of the AMS3108 is inversely proportional to the size of the bypass capacitor. Applications requiring a slow ramp-up of output voltage should consider larger values of bypass capacitance. Likewise, if rapid turnon is necessary, consider omitting CBYP. 02/11/2010 Because the ByPass (BYP) pin is high-impedance, careful considering must be taken in the PCB layout to minimize noise pickup, and capacitors must be selected to minimize current leakage. Current leakage into the BYP pin will directly affect the regulator’s accuracy and should be kept low as possible. Using high quality ceramic and film type’s capacitors are recommended for their low leakage characteristics. Adjustable Version: Feedback Resistor Selection Choosing AMS 3108 with adjustable output voltage option allows the user to select an output voltage by using an external resistor divider. AMS 3108 uses a 0.6V reference voltage at the positive terminal of the error amplifier. To set the output voltage a programming resistor from the adjust pin (ADJ) to ground must be selected (See Pg.1). A 10kΩ resistor is a good selection for a programming resistor R2. A higher value may result in an excessively sensitive feedback node while a lower value will draw more current and degrade the light load efficiency. The equation for selecting the voltage specific resistor is: R1 = Vout Vref -1 ·R2 = 1.8V 0.6V -1 ·10kΩ = 20kΩ Table 1: Adjustable Feedback Resistor values R1 (kΩ) VOUT (V) (R2=10kΩ) 1.8 20.0 2.5 31.6 3.3 45.3 5.0 73.2 Power Good During operation, fault conditions can occur unexpectedly. Such conditions include input voltage dropout (low VIN), overheating, or overloading (excessive output current). If any of these conditions occurs, the PG pin will set an “error flag”. The PG pin, which is an open-collector output, will go LOW when VOUT is less than 95% or the specified output voltage. When the voltage at VOUT is greater than 95% of the specified output voltage, the PG pin is HIGH. A logic pull-up resistor of 10KΩ is recommended at this output. The pin can be left disconnected if unused. www.advanced-monolithic.com 7 Phone (925) 443-0722 Fax (925) 443-0723 AMS3108 Micropower 700mA Low Noise Fast Transient Response LDO PCB Layout The following guidelines should be followed to insure proper layout. 1. VIN Capacitor. A low ESR ceramic bypass capacitor must be placed as close to the IC as possible. 2. Adjustable (ADJ) Feedback Resistors. The adjustable feedback resistors should be placed as close as possible the IC. Minimize the length of the trace from the feedback pin to the resistors. This is a high impedance node susceptible to interference from external RF noise sources. 3. Ground. 4. For good thermal performance vias are required to couple the exposed tab of the SO-8 package to the PCB ground plane. The via diameter should be 0.3mm to 0.33mm positioned on a 1.2mm grid. 02/11/2010 Output Power and Thermal Limits The AMS3108 junction temperature and current capability depends on the internal dissipation and the junction to case thermal resistance of the SO-8 exposed paddle package. Additionally, the paddle and PCB temperature will be elevated due to the total losses of the LDO and of other circuits mounted to the PCB. Tjmax = Pd·θjc + Tpcb + Tamb The internal losses contribute to the junction temperature rise above the paddle and PCB temperature. www.advanced-monolithic.com 8 Phone (925) 443-0722 Fax (925) 443-0723 AMS3108 Micropower 700mA Low Noise Fast Transient Response LDO Figure 2: AMS3108 Evaluation Board Top Side Figure 3: AMS3108 Evaluation Board Bottom Side 2 1 U1 1 C4 10nF 2 3 4 Vin Enable BYP 8 EN PG 7 GND PG GND ADJ/NC VIN VOUT R3 100k 6 R1 5 AMS3108 Vout C1 10uF C2 22uF C3 n/a R2 10.0k gnd gnd Figure 4: AMS3108 Evaluation Board Schematic Component C1 C2 C3 C4 1.2V 1.8V 2.5V 3.3V 5.0V R1 R2 R3 U1 02/11/2010 Table 2: AMS3108 Evaluation Board Bill of Materials Value Manufacturer Manufacturer Part Number 10µF, 50V, X5R, 1210, Ceramic 22µF, 10V, X5R, 0805, Ceramic Optional Feedforward 10nF, 50V,20%,X7R,0603 10.0kΩ, 0.1W, 0603 1% 20.0kΩ, 0.1W, 0603 1% 31.6kΩ, 0.1W, 0603 1% 45.3kΩ, 0.1W, 0603 1% 73.2kΩ, 0.1W, 0603 1% 10.0kΩ, 0.1W, 0603 1% 100kΩ, 0.1W, 0603 1% Linear Regulator Taiyo Yuden Taiyo Yuden UMK325BJ106KM-T LMK212BJ226MG-T Murata Various Various Various Various Various Various Various AMS GRM188R71H103MA01 CRCW0603xxKxFKEA CRCW0603xxKxFKEA CRCW0603xxKxFKEA CRCW0603xxKxFKEA CRCW0603xxKxFKEA CRCW060310K0FKEA CRCW0603100KFKEA AMS3108 SOIC-8 EDP www.advanced-monolithic.com 9 Phone (925) 443-0722 Fax (925) 443-0723 AMS3108 Micropower 700mA Low Noise Fast Transient Response LDO Ordering Information Device AMS3108S(1)(2) Package SOIC-8 EDP AMS3108S-XX(1)(2)(3) SOIC-8 EDP Notes: 1. Available in tape and reel only. A reel contains 2,500 devices. 2. Available in lead-free package only. Device is fully WEEE and RoHS compliant 3. Need to specify output voltage option ( ) Outline Drawing and Landing Pattern SOIC-8 package dimensions are inches (millimeters) unless otherwise noted. 02/11/2010 www.advanced-monolithic.com 10 Phone (925) 443-0722 Fax (925) 443-0723