* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download MICREL DC to DC Converters
Three-phase electric power wikipedia , lookup
History of electric power transmission wikipedia , lookup
Solar micro-inverter wikipedia , lookup
Electrification wikipedia , lookup
Electrical substation wikipedia , lookup
Power engineering wikipedia , lookup
Current source wikipedia , lookup
Electrical ballast wikipedia , lookup
Audio power wikipedia , lookup
Utility frequency wikipedia , lookup
Voltage optimisation wikipedia , lookup
Resistive opto-isolator wikipedia , lookup
Voltage regulator wikipedia , lookup
Power inverter wikipedia , lookup
Mains electricity wikipedia , lookup
Power MOSFET wikipedia , lookup
Amtrak's 25 Hz traction power system wikipedia , lookup
Alternating current wikipedia , lookup
Distribution management system wikipedia , lookup
Variable-frequency drive wikipedia , lookup
Pulse-width modulation wikipedia , lookup
Opto-isolator wikipedia , lookup
Designing Small, Simple and Efficient DC to DC Converters Andy Cowell Applications Manager Asia Feb 2004 Page 1 MICREL’S DC to DC Converters SMALL SIMPLE and EFFICIENENT Small Any DC to DC converter must be as small as possible for the given application Simple The DC to DC converter must use as few external components as possible, without sacrificing performance Efficient The DC to DC converter must be highest efficiency to minimize any losses Page 2 The Issues – making a DC-DC Small The biggest component of a DC to DC converter are the Inductor L, and the Capacitance C Increasing the switching frequency decreases the size of L and C, but decreases the Efficiency. The DC to DC converter must have high speed loop response to keep the output voltage stable under all conditions with a small value of L and C Page 3 The Issues – Making a DC-DC Simple To make a DC to DC converter simple all the stability components need to be inside the Integrated Circuit The DC to DC converter needs to have high loop speeds without any external components to keep the L and C small Page 4 The Issues – Making a DC-DC Efficient The DC to DC converter needs to have a high switching frequency to keep the L and the C small As the switching Frequency increases the switching losses increase, making it less efficient Note Switching Power Loss in a MOSFET device used in most DC to DC converters , Is proportional to Mosfet gate charge ,Q, x Gate Voltage, Vgs, x Frequency, f A new drive scheme is needed to minimize switching losses Page 5 Introducing MIC2202 Page 6 2MHz PWM Synchronous Buck Regulator 2.2mH 2.3V to 5.5V Input 2.2mF Output down to 0.5V 600mA 1mF MIC2202 Industry’s Smallest Output Components Ultra-fast transient response Over 95% efficient Tiny MSOP-10 and 3mm x 3mm MLF-10L Page 7 MIC2202 Benefits Small Tiny 2.2mH inductor and 1mF capacitor (…or visa-versa, 1mH inductor and 2.2mF capacitor!! ) Few external components 3mm x 3mm MLF package has same pcb area as SOT23 4x better thermal performance than SOT23 Low Noise No variable frequency modes of operation MIC2202 always operates in fixed frequency PWM mode Ideal for noise sensitive applications RF and high speed communications systems Page 8 MIC2202 Benefits FAST! Up to 500KHz closed loop band width Fast transient response allows smaller COUT Ideal for applications that need fastest response DAC-controlled VOUT applications such as CDMA RF Power Efficient >95% efficient Proprietary gate drive minimizes shoot-through current Page 9 How the MIC2202 can use small values of L and C The 2Mhz switching frequency keeps the L and C Low. To Reduce the L and C to Only 2.2uH and 1uF output Capacitor, a very high loop bandwidth was required. Traditionally a tantalum output capacitor is required to add an extra zero into the loop to help stabilize. The MIC2202 uses a 1uF ceramic output capacitor to reduce size A new compensation scheme is needed to achieve high stable bandwidths Page 10 MIC2202 Ultra high Bandwidth loop compensation Internal Error Amplifier Pole 60dB Gain (dB) 40dB Internal Error Amplifier Zero Internal Compensation Zero Patent Pending Technique 20dB External Double Pole from LC Filter 0dB 0.01 0.1 1.0 10 Frequency (kHz) 100 1000 ULTRA HIGH BW Page 11 MIC2202 Performance: L = 2.2mH , COUT = 1mF Excellent Load Transient Response Switching Waveforms Page 12 High Efficiency with MIC2204 VIN SYNC_OUT CIN INTERNAL SUPPLY BIAS + OSCILLATOR RAMP GENERATOR SYNC_IN - PWM Comparator L VOUT DRIVER SW COUT + Error Amplifier REF GND EN FB High Efficient drive scheme reduces switching losses Page 13 MIC2202 Efficiency Efficiency (1.8Vout) 95 90 Efficiency (%) 85 80 75 70 4.2Vin L = 2.2mH COUT = 1mF 65 3.6Vin 3Vin 60 0 0.1 0.2 0.3 0.4 0.5 0.6 Output Current (A) Page 14 MIC2202 Inductor Selection versus Efficiency Efficiency vs Inductance 100 2.2mH is optimal inductor value for small size and high efficiency 90 80 Efficiency (%) 70 60 MIC2202 works with as low as 1mH inductor for the smallest size 50 VIN = 3.6V VOUT = 1.8V 40 30 Up to 4.7mH inductor for reduced ripple current and higher light load efficiency. 4.7uH Inductor 20 2.2uH Inductor 10 1uH Inductor 0 1 10 100 Output Current (mA) Page 15 MIC2202 Eval Boards 2 evaluation boards are available: MIC2202BMM EV (MSOP-10 package) MIC2202BML EV (3x3 MLF package) VIN VOU T 1cm x 1.3cm pcb area Page 16 MIC2202 Applications 802.11 WLAN power supply Camera / video chip power Cellular phones PDAs Digital cameras CDMA Dynamic VOUT RF Power Amp power supply Wireless and DSL modems Storage drives CD/DVD ROM power PHY core and I/O power supply ASIC / FPGA / DSP / CPU power supply Portable applications Page 17 A High Power Guide to the World of Low Power DC to DC Converters Andy Cowell Applications Manager Asia Email [email protected] Tel +64 6 378 9799 WWW.MICREL.COM Page 18 Technical Sheet – Buck Converter Buck - Technical Sheet ISW SW IL + Vin + ID ON OFF ON OFF ON OFF Vin VSW Vout t IL IL Vout(DC) = .Vin where the duty cycle t ton T ISW Slope , di Vin Vout dton L Slope , di VD Vout dtoff L ton t T ID t Page 19 Selector Guides Micrel Part number. Feature Synchrous Buck? External Switch(es) required Switching Frequency Input Voltage (Volts DC) Output Current Min Output voltage MIC2202/4 ** Ultra small L and C for up to 600mA out YES No 2 MHz 2.7 to 5.5V 50mA600mA 0.5V MIC2168/9 ** Small size Buck controller YES YES 1Mhz/500k Hz 3 to 14V 500mA-20A 0.8V MIC4680/4 ** Small Simple NO NO 200kHz 4.5-34V 1-1.5A 1.25V MIC4685 Small Simple NO NO 200kHz 4.5V-32V 3A 1.25V MIC2193/4 Low voltage SO-8 controller YES YES 400Khz 2.9V-14V 500mA-10A 1.25V MIC2183/4 Flexable SO-16 Controller Ics YES YES 200/400KHz 2.9V-14V 500mA-10A 1.25V MIC2198/9 Utra small High voltage Buck YES YES 200/400Khz 4.5-32V 500mA-20A 1V MIC2182 Controller with light load mode YES YES 200Khz 4.5V to 32V 500mA to 20A 1.25V ** Most popular Page 20 MIC2168/9 Small, Simple DC/DC Controllers Page 21 MIC2168/9 Simple Synchronous Buck Controllers 3VIN to 14.5VIN VOUT down to 0.8V 500KHz fixed frequency PWM (MIC2169) 1MHz fixed frequency PWM (MIC2168) VIN Up to 97% efficiency No sense resistor Output over-voltage protection Adaptive gate drive CIN RSET VIN VDD BST CS MIC2169 MSOP-10 HS VSW COMP/EN GND 0.5 to 1.5K 1mH VOU T FB LS COUT Page 22 MIC2168/9 Features Wide 3V to 14.5 operating range Works from 3.3V, 5V, and 12V power busses Internal bootstrap allows single supply operation Other solutions require split supply operation VOUT range 0.8V to Powers the latest ICs 12V; IOUT up to 20A Adaptive gate drive Allows up to 97% efficiency Prevents shoot-through current High-side n-channel MOSFET current sensing No current-sense resistor saves cost and efficiency Page 23 MIC2168/9 Features Dual mode current limit allows fastest recovery time Output over-voltage protection Reduces in-rush current Dual function COMP / EN pin Allows ultra-fast transient response Internal soft-start Protects system downstream in fault conditions Hysteretic transient recovery mode Hard current limit until VOUT drops ~16% Hiccup current limit after VOUT drops below 16% (output short-circuit protection) Pull this pin to ground for low power shutdown mode Flexible architecture Tantalum capacitor capable for most applications All-ceramic capacitor capable for smallest size Electrolytic capacitor capable for lowest cost Page 24 MIC2168/9 Applications Point-of-Load DC/DC Conversion Telecom/Networking/Datacom systems DSP / CPU / FPGA / ASIC power supplies Set top boxes Graphics Cards LCD Power Supplies Cable modems HDD and tape drives DC/DC SIP modules Page 25 MIC2168 versus MIC2169 MIC2168 (1MHz) Use for smallest size applications 1MHz operation allows smaller external inductor The trade off with higher frequency is slightly less efficiency (up to ~35%) and lower output current MIC2168 is optimal for < ~5A applications MIC2169 (500KHz) Use for highest current applications that require the most efficiency Page 26 MIC2169 Proprietary Adaptive Gate Drive Typical dc/dc controllers sacrifice efficiency by having a long fixed dead time between the high- and low-side MOSFET drivers to prevent shoot-through current. The dead time needs to account for maximum MOSFET gate capacitance. Though it prevents shoot-through, efficiency is lost during the low-side MOSFET parasitic diode or external Schottky diode conduction time. The MIC2168/9 self-adjusts the dead-time from 30ns to 100ns to maximize efficiency and prevent shoot-through VIN HS VSW MIC2169 LS VOUT COUT No Shoot-Through! Page 27 MIC2169 Internal Soft Start Turn on characteristic, VOUT rise time: 2ms rise time Reduces inrush current Page 28 MIC2169 Output Over-Voltage Protection Output OVP protects load in fault conditions eg: solder-bridge in assembly, or if high-side NFET fails short Low-side NFET turns on during output OVP conditions Blows input fuse to protect the expensive downstream load (1A current limited for benign test) OVP Test Circuit: Switch High Voltage to MIC2169 Output OVP Test Inductor Current sinking 1A Page 29 MIC2169 All Ceramic Capacitor Circuit VIN 5V SD103B CIN 10mF 100mF 0.1mF VIN VDD BST CS MIC2169 MSOP-10 470 IRF7821 HS 2.5mH VSW 0.1mF 8.2K COMP/EN GND 10K 110 IRF7821 FB LS 470pF VOUT 3.3V COUT 4A 100mF 3.16K Page 30 MIC2169 All Ceramic Circuit Performance 5VIN to 3.3VOUT Efficiency Efficiency (%) 100 96 92 88 84 80 0 1 2 3 4 5 ILOAD (A) Page 31 MIC2169 Ceramic Circuit Bode Plot STABLE! 54 Phase Margin 29kHz cross-over frequency Page 32 MIC2169 7A Eval Board Available on on-line sample order system 1.75” 4.5c m VIN MIC2169 CIN VOUT selector jumpers N-Channel MOSFETs 2” 5cm Inductor COUT TOP VOUT BOTTOM Page 33 VIN 5V to68mF (x2) 12V MIC2169 7A General Purpose Eval Board SD103B 10mF 10 10mF 0.1mF 0.1mF 1mF VIN VDD MIC2169 MSOP-10 0.1mF (optional) 100K 4.02K COMP/EN GND VOUT HS 1.2mH LS ) 4.02 * FB (Jumper Adjustable IRF7821 VSW Shut 2N7002 Down 470 BST CS IRF7821 10K 47 330mF (x2) 0.1mF (optional) 1N5819 * 100pF Jumper * Light snubbing is required for super low duty cycle applications to maintain accurate current limiting (ex: 12VIN to 1VOUT applications) . These components can be removed for applications with higher duty cycle. Page 34 MIC2169 Eval Board Performance Eval Board Efficiency Efficiency(%) 100 95 VIN=5V, VOUT=3.3V 90 VIN=12V, VOUT=3.3V 85 80 0 2 4 6 8 10 ILOAD(A) Eval Board supports 10A with airflow, 7A without. Current is limited by the PCB thermals Page 35 MIC2169 Eval Board Bode Plot (12VIN to 3.3VOUT ) STABLE! 64 Phase Margin 26kHz cross-over frequency Page 36 Technical Sheet – Boost Converter Boost - Technical Sheet IL SW OFF ON OFF ON OFF ID ID + ON Slope , di V in V out V D dtoff L Iout + t ISW Slope , ISW di V in dton L ton t Vout(DC) = Vin 1- where the duty cycle ton T IL IL T t Vout VSW t Page 37 Selector guide- Boost Micrel Part number. Feature Synchrono us Boost? External Switch(es) required Switching Frequency Input Voltage (Volts DC) Output Current Max Output voltage MIC2288 ** Small SOT23 Package, high output power NO NO 1.2 MHz 2.5- 10V Up to 500mA 34V MIC2290 ** 2288 with internal schottky diode YES NO 1.2MHz 2.5V- 10V Up to 300mA 34V MIC2196 ** Small Simple in SO-8 NO YES 400kHz 2.9V-14V 5A+ >50V MIC2171 High power Boost with internal switch NO NO 100Khz 3.0V-40V 3A 60V MIC2185/6 Flexable SO-16 Controller Ics YES YES 200/400K Hz 2.9V-14V 5A+ >50V MIC2145 High Power MSOP8 NO NO 450Khz 2.2V-14V Up to 700mA 18V MIC3171/2 High voltage simple SO-8 NO NO 100Khz 3V - 40V 500mA 60V MIC2141/2 Small SOT23 NO NO 330kHz 2.7-16V to 100mA 18V ** Most popular Page 38 MIC2288 Boost Regulator 2.5V to 10VIN 1.2MHz fixed frequency PWM >1A switch current Up to 34VOUT 15V / 100mA 10mH 2.2mF 1-Cell Li Ion SW VIN EN MIC2288 Tiny 2x2mm MLF-8L and Thin SOT23-5L package options 4.7mF FB GND Page 39 MIC2288 Boost Regulator 15VOUT Efficiency 90 Efficiency (%) 85 80 75 70 VIN = 4.2V VIN = 3.6V 65 L = 10mH COUT = 10mF VIN = 3.2V 60 0 0.05 0.1 0.15 0.2 Load (A) Page 40 MIC2288 Boost Regulator Total Regulation 15.2 VOUT (V) 15.15 15.1 VIN = 4.2V 15.05 VIN = 3.6V VIN = 3.2V 15 0 0.05 0.1 0.15 0.2 Load (A) Page 41 MIC2288 Load Transient Performance 12VOUT 150mA 50mA L = 10mH COUT = 10mF Page 42 MICREL DC to DC Converters For Small Simple Efficient DC to DC Converters Think MICREL Page 43