Product Change Notices PCN No.: 20110806 Date: 8/19/2011 This is to inform you that AME5290 datasheet has been changed from Rev. A.01 to Rev. B.01. This notification is for your information and concurrence. If you require data or samples to qualify this change, please contact AME, Inc. within 30 days of receipt of this notification. If we do not receive any response from you within 30 calendar days from the date of this notification, we will consider that you have accepted this PCN. If you have any questions concerning this change, please contact: PCN Originator: Name: Bill Chou Email: [email protected] Expected 1st Device Shipment Date: N/A Earliest Year/Work Week of Changed Product: N/A Description of Change : Modify absolute maximum ratings From: To: Reason for Change: To comply AME5290 part real product performance. QPM018B-B AME AME5290 3A, 1MHz Sync Buck Converter n General Description The AME5290 is a synchronous buck converter with internal power MOSFETs. It achieves 3A continuous output current with a fixed frequency of 1MHz with excellent load and line regulation. The device operates from an input voltage of 3V to 5.5V and provides an output voltage from 0.8V to VIN, making the AME5290 ideal for onboard post regulation applications. Internal soft-start minimizes the inrush supply current at startup. The circuit protection includes cycle-by-cycle current limiting, output short circuit frequency protection and thermal shutdown these protect functions improve design reliability. This device is available in SOP-8/PP package with exposed pad for low thermal resistance. n Features l Input Voltage Operate from 3V to 5.5V l 3A Output Current l 100mΩ Internal Power MOSFET Switch l Stable with Low ESR Output Ceramic Capacitors l Up to 95% Efficiency l Thermal Shutdown l Output Adjustable from 0.8V to V IN l Short Circuit Frequency Protection l Over Temperature Protection l Available in SOP-8/PP Package l Green Products Meet RoHS Standards n Applications l TV l Distributed Power Systems l Pre-Regulator for Linear Regulators Rev.B.01 1 AME AME5290 3A, 1MHz Sync Buck Converter n Typical Operating Circuit L 2.2µH VIN 5V SW VIN CFB * (option) RIN 10Ω CIN 10µF AME5290 VCC FB R1 50KΩ CVCC 0.1µF EN ON VOUT 3.3V OFF REF GND PGND COUT 22µF R2 16KΩ Cref 0.1µF R1 VOUT = 0.8V × 1 + R2 n Functional Block Diagram VCC IN 250K EN Enable Current Sense UVLO 4.5A Current Limit OSC SLOPE REF Softstart 11.5K LOGIC + 0.8V VREF EA + - Driver SW PWM GND OTP FB PGND 0.9V 2 IRCMP OVP Rev.B.01 AME AME5290 3A, 1MHz Sync Buck Converter n Pin Configuration SOP-8/PP Top View 8 7 6 5 AME5290-AZAxxx 1. VCC 2. REF 3. GND AME5290 4. FB 5. EN 6. PGND 1 2 3 4 7. SW 8. IN * Die Attach: Conductive Epoxy Note: Connect exposed pad (heat sink on the back) to GND. n Pin Description Pin Number Pin Name Rev.B.01 Pin Description 1 VCC Supply Voltage. Bypass with 0.1µF capacitor to ground and 10Ω resistor to VIN . 2 REF Reference Bypass. Bypass with 0.1µF capacitor to ground. 3 GND Ground. Connect the exposed pad to GND. 4 FB Feedback Input. FB senses the output voltage to regulate that voltage. Drive FB with a resistive voltage divider from the output voltage. The feedback reference voltage is 0.8V. 5 EN Enable. Internal pull high with a resistor. Pull EN below 0.4V to shut down the regulator. 6 PGND 7 SW 8 IN Power Ground. Internally connected to GND. Keep power ground and signal ground planes separate. Power Switching Output. SW is the switching node that supplies power to the output. Connect the output LC filter from SW to the output load. Power-Supply Voltage. Input voltage range from 3V to 5.5V. Bypass with a 10µF (min.) ceramic capacitor to ground and a 10Ω resistor to VCC. 3 AME AME5290 3A, 1MHz Sync Buck Converter n Ordering Information AME5290 - x x x xxx Output Voltage Number of Pins Package Type Pin Configuration Pin Configuration A (SOP-8/PP) 4 1. VCC 2. REF 3. GND 4. FB 5. EN 6. PGND 7. SW 8. IN Package Type Z: SOP/PP Number of Pins A: 8 Output Voltage ADJ: Adjustable Rev.B.01 AME AME5290 3A, 1MHz Sync Buck Converter n Available Options Part Number Marking* Output Voltage Package Operating Ambient Temperature Range AME5290-AZAADJ A5290 AMyMXX ADJ SOP-8/PP -40oC to +85oC Note: 1. The first 2 places represent product code. It is assigned by AME such as AM. 2. y is year code and is the last number of a year. Such as the year code of 2008 is 8. 3. A bar on top of first letter represents Green Part such as A5290. 4. The last 3 places MXX represent Marking Code. It contains M as date code in "month", XX as LN code and that is for AME internal use only. Please refer to date code rule section for detail information. 5. Please consult AME sales office or authorized Rep./Distributor for the availability of output voltage and package type. n Absolute Maximum Ratings Parameter Maximum Unit -0.3V to +6V V Switch Voltage -1V to +6V V EN, FB to GND -0.3V to (VCC + 0.3V) V PGND to GND -0.3V to +0.3V V VIN, VCC, REF to GND B* ESD Classification Caution: Stress above the listed in absolute maximum ratings may cause permanent damage to the device. * HBM B: 2000V ~ 3999V n Recommended Operating Conditions Parameter Symbol Rating Ambient Temperature Range TA -40 to +85 Junction Temperature Range TJ -40 to +125 Storage Temperature Range TSTG -65 to +150 Rev.B.01 Unit o C 5 AME AME5290 3A, 1MHz Sync Buck Converter n Thermal Information Parameter Package Die Attach Thermal Resistance* (Junction to Case) Symbol Maximum θJC Unit 19 o Thermal Resistance (Junction to Ambient) SOP-8/PP Conductive Epoxy Internal Power Dissipation Maximum Junction Temperature θJA 84 PD 1450 C/W mW 150 o Solder Iron (10Sec)** C 350 * Measure θJC on center of molding compound if IC has no tab. ** MIL-STD-202G 210F 6 Rev.B.01 AME AME5290 3A, 1MHz Sync Buck Converter n Electrical Specifications VIN=5V, TA = 25OC unless otherwise noted. Parameter Input Voltage Range Symbol ISHDN VREF EN Voltage High EN Voltage Low Output Voltage Range Shutdown (EN=0V) VOUT Max Units 5.5 V µA 450 VIN =5V 20 35 µA When SW starts switching 2 V IREF =0, VIN =3V to 5V 0.8 V 2 Logic High VEN Typ 3 No switching (EN=VCC) VCC Undervoltage Lockout Threshold REF Voltage Min VIN Supply Current Shutdown Current Test Condition V 0.4 Logic Low When using external feedback resistors to drive FB 0.8 VIN V Output Voltage Line Regulation VIN =3V to 5V 0.08 %/V Output Voltage Load Regulation 0A<ILOAD <3A 0.12 %/A Feedback Voltage (Error Amp Only) VFB VIN =3V to 5V 0.784 FB Input Bias Current 0.8 -0.1 High-side Switch On Resistance RDSON,HI VIN =5V 100 Low-side Switch On Resistance RDSON,LOW VIN =5V 80 High-side Switch Current Limit Duty cycle=100%, V IN =3V to 5V Low-side Switch Current Limit Switch Leakage Current ISWLK VIN =5V High-side 3.4 0.816 V 0.1 µA mΩ 4.5 A Low-side -1.3 VSW =5V SW=GND 10 -10 µA Current Limit Oscillation Frequency fOSC,CL VIN =3V to 5V 1 MHz Short Current Oscillation Frequency fOSC,SCR VFB=0V 120 KHz SW Maximum Duty Cycle DSW,MAX VSW =high-Z, VIN =3V to 5V SW Minimum Duty Cycle t SWON,MIN VIN =3V to 5V Rev.B.01 100 % 15 7 AME AME5290 3A, 1MHz Sync Buck Converter n Electrical Specifications ( Contd. ) Symbol Thermal Shutdown Temperature OTP Thermal Shutdown Hysteresis OTH 20 t ON,MIN 150 Minimum On Time 8 Test Condition Parameter When SW starts/stops switching Min TJ rising Typ 160 Max Units o C ns Rev.B.01 AME AME5290 n Detailed Description The AME5290 high-efficiency switching regulator is a small, simple, DC-to-DC step-down converters capable of delivering up to 3A of output current. The devices operate in pulse-width modulation (PWM) at a fixed frequency of 1MHz from a 3V to 5.5V input voltage and provide an output voltage from 0.8V to VIN, making the AME5290 ideal for on-board post-regulation applications. The high switching frequency allows for the use of smaller external components, and internal synchronous rectifiers improve efficiency and do not use the typical Schottky freewheeling diode. Using the on-resistance of the internal high-side MOSFET to sense switching currents eliminates current-sense resistors, further improving efficiency and cost. The AME5290 step-down converters use a PWM current- mode control scheme. An open-loop comparator (Modulator) compares the amplified voltage-feedback signal against the sum of the amplified current-sense signal and the slope compensation ramp. At each rising edge of the internal clock, the internal high-side MOSFET turns on until the PWM comparator trips. During this on-time, current ramps up through the inductor, sourcing current to the output and storing energy in the inductor. The current-mode feedback system regulates the peak inductor current as a function of the output voltage error signal. Since the average inductor current is nearly the same as the peak inductor current (<30% ripple current ). The circuit acts as a switch-mode transconductance amplifier. To preserve inner-loop stability and eliminate inductor stair-casing, a slope-compensation ramp is summed into the main PWM comparator. During the second half of the cycle, the internal high-side P-channel MOSFET turns off, and the internal low-side N-channel MOSFET turns on. The inductor releases the stored energy as its current ramps down while still providing current to the output. The output capacitor stores charge when the inductor current exceeds the load current, and discharges when the inductor current is lower, smoothing the voltage across the load. Rev.B.01 3A, 1MHz Sync Buck Converter Current Limit The internal high-side MOSFET has a current limit of 4.5A (typ.). If the current flowing out of SW exceeds this limit, the high-side MOSFET turns off and the synchronous rectifier turns on. This lowers the duty cycle and causes the output voltage to droop until the current limit is no longer exceeded. A synchronous rectifier current limit of -1.3A (typ.) protects the device from current flowing into SW. If the negative current limit is exceeded, the synchronous rectifier turns off, forcing the inductor current to flow through the high-side MOSFET body diode, back to the input, until the beginning of the next cycle or until the inductor current drops to zero. The AME5290 uses a pulse-skip mode to prevent overheating during short-circuit output conditions. The device enters pulseskip mode when the FB voltage drops below 300mV, limiting the current to 4.5A (typ.) and reducing power dissipation. Normal operation resumes upon removal of the short-circuit condition. Over Voltage Protection The AME5290 monitors a resistor divided feedback voltage to detect over voltage. When the feedback voltage becomes higher than the target voltage for 12% (typ.), the OVP comparator output goes high and the circuit latches as the high-side MOSFET turned OFF and lowside MOSFET turned ON cycle by cycle. Soft-Start The AME5290 employ soft-start circuitry to reduce supply inrush current during startup conditions. Thermal-Overload Protection Thermal-overload protection limits total power dissipation in the device. When the junction temperature exceeds TJ = +160oC, a thermal sensor forces the device into shutdown, allowing the die to cool. The thermal sensor turns the device on again after the junction temperature cools by 20oC, resulting in a pulsed output during continuous overload conditions. 9 AME AME5290 Undervoltage Lockout If VCC drops below 1.8V, the UVLO circuit inhibits switching. Once VCC rises above 2V, the UVLO clears, and the soft-start sequence activates. Shutdown Mode The EN pin has a internal pull high resistor connect to VCC. To shut down the AME5290, use an NPN bipolar junction transistor or a MOSFET to pull EN to GND. Shutdown mode causes the internal MOSFETs to stop switching, forces SW to a high-impedance state, and shorts REF to GND. Release EN to exit shutdown and initiate the soft-start sequence. VCC Decoupling Due to the high switching frequency and tight output tolearance, decouple VCC with a 0.1µF capacitor connected from VCC to GND, and a 10Ω resistor connected from VCC to VIN. Place the capacitor as close to VCC as possible. 3A, 1MHz Sync Buck Converter n Application Information Inductor Selection Use a 2µH inductor with a minimum 3A-rated DC current for most application. For best efficiency, use an inductor with a DC resistance of less than 20mΩ and a saturation current grater than 4A(min). For most designs, derive a reasonable inductor value(LINIT) from the following equation: L INIT = VOUT * (VIN - V OUT) / (VIN * LIR * IOUT(MAX) * fSW) where fSW is the switching frequency (1MHz typ) of the oscillator. Keep the inductor current ripple percentage LIR between 20% and 40% of the maximum load current for the best compromise of cost, size, and performance. Calculate the maximum inductor current as: IL(MAX) = (1+LIR / 2) * IOUT(MAX) Check the final values of the inductor with the output ripple voltage requirement. The output ripple voltage is given by: VRIPPLE = VOUT * (VIN - VOUT) * ESR / (VIN * LFINAL * fSW ) Where ESR is the equivalent series resistance of the output capacitor. Capacitor Selection The input filter capacitor reduces peak currents drawn from the power source and reduces noise and voltage ripple on the input caused by the circuit's switching. The input capacitor must meet the ripple current requirement(IRMS) imposed by the switching currents defined by the following equation: IRMS = (1 / VIN) * (IOUT2 * VOUT * (VIN - VOUT))1/2 For duty ratios less than 0.5, the input capacitor RMS current is higher than the calculated current. Therefore, use a +20% margin when calculating the RMS current at lower duty cycles. Use ceramic capacitors for their low ESR, equivalent series inductance (ESL), and lower cost. Choose a capacitor that exhibits less than 10oC temperature rise at the maximum operating RMS current for optimum long-term reliability. After determining the input capacitor, check the input ripple voltage due to capacitor discharge when the high-side MOSFET turns on. Calculate the input ripple voltage as follows: VIN_RIPPLE = (IOUT * VOUT) / (fSW * VIN * CIN) 10 Rev.B.01 AME AME5290 Keep the input ripple voltage less than 3% of the input voltage. The key selection parameters for the output capacitor are capacitance, ESR, ESL, and the voltage rating requirements. These affect the overall stability, output ripple voltage, and transient response of the DC-toDC converter. The output ripple occurs due to variations in the charge stored in the output capacitor, the voltage drop due to the capacitor's ESR, and the voltage drop due to the capacitor's ESL. Calculate the output voltage ripple due to the output capacitance, ESR, and ESL as: 3A, 1MHz Sync Buck Converter Efficiency Considerations where the output ripple due to output capacitance, ESR, and ESL is: Although all dissipative elements in the circuit produce losses, one major source usually account for most of the losses in AME5290 circuits: I2R losses. The I2R loss dominates the efficiency loss at medium to high load currents. The I2R losses are calculated from the resistances of the internal switches, RSW, and external inductor RL. In continuous mode, the average output current flowing through inductor L is "chopped" between the main switch and the synchronous switch. Thus the series resistance looking into the SW pin is a function of both top and bottom MOSFET RDS(ON) and the duty cycle (D) as follows: VRIPPLE(C) = IP-P / (8 x COUT x fSW) RSW = (RDS(ON)TOP)(D) + (RDS(ON)BOTTOM )(1-D) VRIPPLE(ESR) = IP-P x ESR The RDS(ON) for both the top and bottom MOSFETs can be obtained from Electrical Characteristics table. Thus, to obtained I2R losses, simply add RSW to RL and multiply the result by the square of the average output current. Other losses including CIN and COUT ESR dissipative losses and inductor core losses generally account for less than 2% total additional loss. VRIPPLE = VRIPPLE(C) + VRIPPLE(ESR) + VRIPPLE(ESL) VRIPPLE(ESL) = (IP-P / tON) x ESL or (IP-P / tOFF) x ESL whichever is greater and IP-P the peak-to-peak inductor current is: IP-P = [ (V IN-V OUT) / fSW x L)] x VOUT / VIN Use these equations for initial capacitor selection, but determine final values by testing a prototype or evaluation circuit. As a rule, a smaller ripple current results in less output voltage ripple. Since the inductor ripple current is a factor of the inductor value, the output voltage ripple decreases with larger inductance. Use ceramic capacitors for their low ESR and ESL at the switching frequency of the converter. The low ESL of ceramic capacitors makes ripple voltages negligible. Load transient response depends on the selected output capacitor. During a load transient, the output instantly changes by ESR * ILOAD . Before the controller can respond, the output deviates further, depending on the inductor and output capacitor values. After a short time, the controller responds by regulating the output voltage back to its nominal state. The controller response time depends on the closed-loop bandwidth. A higher bandwidth yields a faster response time, thus preventing the output from deviating further from its regulating value. Thermal Considerations In most application the AME5290 does not dissipate much heat due to its high efficiency. But, in applications where the AME5290 is running at high ambient temperature with low supply voltage and high duty cycles, such as in dropout, the heat dissipated may exceed the maximum junction temperature of the part. If the junction temperature reaches approximately 150oC, both power switches will be turned off and the SW node will become high impedance. Thermal performance can be improved with one of the following options: l Increase the copper areas connected to GND, SW, and VIN l Provide thermal vias next to GND and VIN, to the ground plane and power plane on the Output Voltage Programming The output voltage is set by resistive divider according to the following formula: VOUT = 0.8 x (1+R1/R2) Please keep R2 not larger than 25KΩ and select R1 using the formula. Rev.B.01 back side of PC board, with openings in the solder mask next to the vias to provide better thermal conduction. l Provide forced-air cooling to further reduce case temperature 11 AME AME5290 3A, 1MHz Sync Buck Converter PC Board Layout Considerations Careful PC board layout is critical to achieve clean and stable operation. The switching power stage requires particular attention. Follow these guidelines for good PC board layout: l Place decoupling capacitors as close to the IC as possible. Keep power ground plane(connected to PGND) and signal ground plane(connected to GND) separate l Connect input and output capacitors to the power ground plane; connect all other capacitors to the signal ground plane Note: Connect exposed pad (heat sink on the back) to GND. 12 Rev.B.01 AME AME5290 3A, 1MHz Sync Buck Converter n Characterization Curve Efficiency vs. Output Current Load Step 100 90 Efficiency(%) 80 VOUT=3.3V 70 1 VOUT=2.5V 60 50 40 30 20 VIN = 5.0V 10 0 1 10 100 1000 2 10000 200µS / div Output Current(mA) VIN=5V VOUT=3.3V IOUT=5mA~3A O TA = 25 C 1) VOUT= 200mV/div (AC) 2) IOUT = 1A/div Output Voltage Ripple (Full Load) Start-Up 1 1 2 2 3 3 4 4 1mS / div 400nS / div 1) VIN= 500mV/div 2) VOUT= 10mV/div 3) IL = 2A/div 4) IOUT = 2A/div Rev.B.01 1) EN= 2V/div 2) VOUT= 2V/div 3) IIN = 2A/div 4) IOUT = 2A/div 13 AME AME5290 3A, 1MHz Sync Buck Converter n Characterization Curve ( Contd. ) VFB vs. Temperature Frequency vs. Temperature 0.83 1200 VIN = 5.0V VOUT = 3.3V 0.82 1100 Frequency(KHz) 0.81 VFB(V) 0.80 0.79 0.78 0.77 1000 900 800 0.76 0.75 -50 -25 0 +25 +50 +75 +100 700 -50 +125 0 +75 +100 Frequency vs. Output Current +125 1200 VOUT = 3.3 V VIN = 5.0V VOUT = 3.3V 1100 Frequency(KHz) 1000 900 1000 900 800 800 700 4.00 700 4.25 4.50 4.75 5.00 5.25 5.50 0 500 1000 VIN(V) 550 550 Quiescent Current(µA) 600 500 450 400 350 4. 25 4.50 4.75 VIN(V) 2000 2500 3000 Quiescent Current (No Switching) vs. Temperature 600 300 4.00 1500 IO(mA) Quiescent Current (No Switching) vs. Input Voltage Quiescent Current(µA) +50 Frequency vs. Supply Voltage 1100 14 +25 Temperature(°C) 1200 Frequency(KHz) -25 Temperature(°C) 5.00 5. 25 5.50 500 450 400 350 300 -50 -25 0 +25 +50 +75 +100 +125 Temperature(°C) Rev.B.01 AME AME5290 3A, 1MHz Sync Buck Converter n Date Code Rule Month Code 1: January 7: July 2: February 8: August 3: March 9: September 4: April A: October 5: May B: November 6: June C: December n Tape and Reel Dimension SOP-8/PP P PIN 1 W AME AME Carrier Tape, Number of Components Per Reel and Reel Size Rev.B.01 Package Carrier Width (W) Pitch (P) Part Per Full Reel Reel Size SOP-8/PP 12.0±0.1 mm 4.0±0.1 mm 2500pcs 330±1 mm 15 AME AME5290 3A, 1MHz Sync Buck Converter n Package Dimension SOP-8/PP TOP VIEW SIDE VIEW D1 θ E1 E2 E L1 C SYMBOLS MILLIMETERS INCHES MIN MAX MIN MAX A 1.350 1.750 0.053 0.069 A1 0.000 0.150 0.000 0.006 A2 1.350 1.600 0.053 0.063 C 0.100 0.250 0.004 0.010 E 3.750 4.150 0.148 0.163 E1 5.700 6.300 0.224 0.248 L1 0.300 1.270 0.012 0.050 b 0.310 0.510 0.012 0.020 D 4.720 5.120 0.186 0.202 PIN 1 D e A1 FRONT VIEW 16 A A2 b 1.270 BSC e o 0.050 BSC o o 8o θ E2 2.150 2.513 0.085 0.099 D1 2.150 3.402 0.085 0.134 0 8 0 Rev.B.01 www.ame.com.tw E-Mail: [email protected] Life Support Policy: These products of AME, Inc. are not authorized for use as critical components in life-support devices or systems, without the express written approval of the president of AME, Inc. AME, Inc. reserves the right to make changes in the circuitry and specifications of its devices and advises its customers to obtain the latest version of relevant information. AME, Inc. , August 2011 Document: HU003-DS5290-B.01 Corporate Headquarter AME, Inc. 2F, 302 Rui-Guang Road, Nei-Hu District Taipei 114, Taiwan. Tel: 886 2 2627-8687 Fax: 886 2 2659-2989