High Efficiency Monitor Power Design Using AIC1578 Michael Huang

The Datasheet Archive - 100 Million Datasheets from 7500 Manufacturers.

High Efficiency Monitor Power Design Using AIC1578 Michael Huang

Datasheet Thumbnail

Top Searches for this datasheet

AN99-SR01EN
High Efficiency Monitor Power Design Using AIC1578
Michael Huang
DESCRIPTION
AIC1578 high performance step-down DC/DC converter, designed drive external Pchannel MOSFET generate programmable output voltage. main schematics Pulse-Skipping Pulse-Frequency Modulation employed maintain quiescent current high conversion efficiency under wide ranges input voltage loading condition. current sense comparator with both inverting non-inverting input uncommitted included provide crucial function either current limit protection constant output current control. When AIC1578 used high-side current source step-down constant current source, efficiency typically greater than 90%. Duty cycle adjusted greater than connecting external resistor from DUTY VIN. Switching frequency being around 90KHZ 280KHZ range, small size switching components ideal portable equipment.
order maintain good conversion efficiency from light load full load, AIC1578 uses intermittent switch control method (PulseFrequency Modulation rather than conventional control method, Fig1. shows function diagram AIC1578. When feedback voltage greater than reference voltage (1.22V), output Amp. Low, drives Pin6 Level, thus turn outside drive device(P MOSFET). While feedback voltage lower than reference voltage, drive DRI( Pin6 Level, turn outside drive device. This kind control method works similar full load, with stable switch waveform, Whereas light load, uses intermittent switching efficiently sustain output loading requirements.
60mV
Output
Fig1. AIC1578 Function Block ANALOG INTEGRATIONS CORPORATION
Industry Road, Science-based Industrial Park Hsinchu, Taiwan, R.O.C.
www. analog.com.tw
TEL: (8863)577-2500 FAX:(8863)577-2510
AN99-SR01EN
addition, AIC1578 converter following feature: Able operate under input voltage range from 20V. Output voltage level adjusted externally. design automatically adjusted switching frequency duty cycle, which makes possible obtain highly efficient conversion over wide input output voltage range. Build-in shutdown mode control Works high frequency range from 90KHZ
280KHZ, only small size inductors required. Complementary push-pull output, drive
external P-channel MOSFET transistor. cost.
Buck Switching Regulator Topology
Basic operation: Fig. shows basic topology Buck DC/DC converter (switching regulator).
Drive Signal Current Signal VOUT Output Voltage Waveform
VOUT
IOUT
LOAD
CONTROL CIRCUIT
Fig2. Typical Buck Converter Topology while maintaining high conversion efficiency good stability. order choose appropriate switching converter electronic product, therefore, factors need considered: current rating regulation output current should meet product's demands. High conversion efficiency. power consumption. Small size light weight.
basic operation principle using feedback signal control ON/OFF power switch order obtain specified output voltage. power applications, conventional control schemes ideal, because first, conversion efficiency high switching losses compared with output power, second, fact that controller requires minimum load maintain stability. most efficient reliable control method then Pulse-Skipping-Modulation switching control with control waveforms shown Fig. This switching control method DC/DC converter into quasi-sleeping mode under load light load condition, which reduces switching losses ANALOG INTEGRATIONS CORPORATION
Industry Road, Science-based Industrial Park Hsinchu, Taiwan, R.O.C.
www. analog.com.tw
TEL: (8863)577-2500 FAX:(8863)577-2510
AN99-SR01EN
Oscillator Output Error Comparator Input Error Comparator Output Driver Output
Sensed Output
VREF
Time Sequence Waveform
TYPICAL APPLICATION
circuit shown Fig.4 output power MONITOR, when between 14V, high efficiency obtained full load.
Power Specification Item Input Voltage Output Voltage Output Current Output Ripple Voltage Symbol Min. Typ. Max. Unit VOUT IOUT VRIPPLE 4.75 0.2A 5.25
ANALOG INTEGRATIONS CORPORATION
Industry Road, Science-based Industrial Park Hsinchu, Taiwan, R.O.C.
www. analog.com.tw
TEL: (8863)577-2500 FAX:(8863)577-2510
AN99-SR01EN
:10V~14V 220uF 0.01uF DUTY SHDN AIC1578 CSDRI 4435 470uF 0.1uF 470uF Vripple 100mV
1N5820 47uH VOUT1: 5V/2A Vripple <50mV 300PF 47KF 15KF 470uF 470uF 0.1uF
VOUT2: 3.3V/1A
VOUT AIC1085
MOMITOR POWER SOLUTION(1) Switching
10uF
10uF
750RF
1.2KF
Fig4. AIC1578 MONITOR Power solution
Fig5. Frequency Duty Cycle 27°C Duty Frequency
Fig6. Duty Cycle RDUTY
VIN=5V Frequency (KHz)
Duty Cycle
Duty
VIN=10V VIN=15V
VIN=20V
DUTY refer Typ. App. Circuit.
RDUTY
ANALOG INTEGRATIONS CORPORATION
Industry Road, Science-based Industrial Park Hsinchu, Taiwan, R.O.C.
www. analog.com.tw
TEL: (8863)577-2500 FAX:(8863)577-2510
AN99-SR01EN
(ii) Design note Component selection:
Switching losses These losses encountered during MOSFET states. They depend nature load well switching speed MOSFET.
Design note
DC-DC Converter efficiency Efficiency POUT IOUT VOUT IOUT VOUT IOUT VOUT PLOSS feedback component R1,R2 following Datasheet equation VOUT =1.22 15K.
VDSID(ts1 ts2)fs switching frequency turn-on time turn-off time :supply voltage drain current
(R1+R2) must larger than meet high efficiency request. noise filter, value depends device's switching frequency. Duty range MOSFET CEM4435 RDS-ON ,1N5820 :VF=0.475V) 0.475 37.9% 0.04 0.475 0.475 0.04 0.475
Select MOSFET factors: RDS-ON CISS Short Reverse recovery time
Duty range 35.5% ,When ,FSW range 180KHZ 230KHZ Duty range 78%. Duty directly connect need larger Duty cycle than typical applications, refer Fig6 RDUTY adjustment. output inductor
(VDC
SCHOTTKY BARRIER RECTIFIER SELECTION Conduction losses Diode losses recovery time conduction strongly related circuit topology load impedance. IOUT (1-D) Forward Conduction Voltage
VO)T 0.2I
Select SCHOTTKY factors forward conduction voltage( Short Reverse recovery time large Reverse Breakdown Voltage -PEAK IL-PEAK
Component selection
Switching MOSFET Selection dominate power dissipation MOSFET consisted parts Conduction losses Switching losses. Conduction losses On-state losses related load current MOSFET ANALOG INTEGRATIONS CORPORATION
Industry Road, Science-based Industrial Park Hsinchu, Taiwan, R.O.C.
Output Capacitors Selection bulk filter capacitor values generally
www. analog.com.tw
TEL: (8863)577-2500 FAX:(8863)577-2510
AN99-SR01EN
determined ESR(effective series resistance) (effective series inductance) parameters rather than actual capacitance. High frequency decoupling capacitors should placed close power pins load physically possible. careful inductance circuit board wiring that could cancel usefulness these inductance component, only specialized low-ESR capacitors intended switching regulator applications bulk capacitors. bulk capacitor's determines output ripple voltage initial voltage drop after high slew-rate transient. aluminum electrolytic capacitor's value related case size with lower available larger case sizes. Output Inductor Selection
output inductor selected meet output voltage ripple requirements sets converter's response time load transient. inductor value determines converter ripple current ripple voltage function ripple current. relationship between ripple voltage current approximate following equation VOUT VOUT VOUT=I
Increasing value inductance reduces ripple current converter's response time load transient.
Efficiency Test:
Input Voltage Input Current 1149 1754 1491 1271 Output Voltage 5.06V 5.06V 5.05V 5.05V 5.06V 5.06V 5.05V 5.06V 5.09V 5.09V 5.08V 5.07V Output Current 1003 2001 3001 1003 2001 3001 1003 2001 3001 Output Load 500mA 500mA 500mA Efficiency 87.8 89.0 87.9 86.4 84.2 86.5 86.1 84.9 84.3 87.0 86.9% 85.5
ANALOG INTEGRATIONS CORPORATION
Industry Road, Science-based Industrial Park Hsinchu, Taiwan, R.O.C.
www. analog.com.tw
TEL: (8863)577-2500 FAX:(8863)577-2510
AN99-SR01EN
2.Temperature Test
LOAD Unit: 1578 34.1 36.7 39.3 40.8 42.4 LOAD 35.5 37.9 38.3 40.2 40.6 32.8 34.5 34.5 34.8 35.1 35.9 36.4 36.6 37.5 39.3 1578 38.1 41.5 43.7 44.3 45.5 LOAD 42.2 48.8 51.2 56.6 58.9 35.1 35.6 36.1 38.7 39.5 44.1 49.9 50.7 62.1 69.4 1578 40.2 45.5 49.7 50.3 53.9 LOAD 51.3 53.3 65.8 66.4 67.2 37.3 38.9 37.4 39.2 44.3 61.1 66.5 70.7 74.6 80.1
3.TEST WAVEFORM:
Switching Signal Switching Signal
CH1:VG-GND DIV) CH2: VS-GND DIV) Status: VOUT= 5.06V Output Load
CH1: VG-GND DIV) CH2: VS-GND DIV) Status: VIN= VOUT= 5.05V Output Load
ANALOG INTEGRATIONS CORPORATION
Industry Road, Science-based Industrial Park Hsinchu, Taiwan, R.O.C.
www. analog.com.tw
TEL: (8863)577-2500 FAX:(8863)577-2510
AN99-SR01EN
FIG3: Switching Signal
FIG4: Switching Signal
CH1: VG-GND DIV) CH2: VS-GND DIV) STATUS: 10Vdc VOUT= 5.05 Output Load
CH1: VG-GND div) CH2: VS-GND div) STATUS: VIN= 10Vdc VOUT= 5.05 Output Load
FIG5: Switching Signal
Switching Signal
CH1: VG-GND DIV) CH2: VS-GND DIV) Status:VIN VOUT= 5.05Vdc Output Load
CH1: VG-GND DIV) CH2: VS-GND DIV) Status: VOUT= 5.06Vdc Output Load
ANALOG INTEGRATIONS CORPORATION
Industry Road, Science-based Industrial Park Hsinchu, Taiwan, R.O.C.
www. analog.com.tw
TEL: (8863)577-2500 FAX:(8863)577-2510
AN99-SR01EN
FIG7: output ripple voltage
Switching Signal
CH1: Output (Ripple Voltage) Status: Input Voltage: Output Load:
CH1: Output (Ripple Voltage) Status: Input Voltage: Output Load:
output ripple
output ripple
CH1: Output (Ripple Voltage) Status: Input Voltage: Output Load:
CH1: Output (Ripple Voltage) Status: Input Voltage: Output Load:
ANALOG INTEGRATIONS CORPORATION
Industry Road, Science-based Industrial Park Hsinchu, Taiwan, R.O.C.
www. analog.com.tw
TEL: (8863)577-2500 FAX:(8863)577-2510
AN99-SR01EN
MONITOR LIST
Reference C1,C2,C3,C4 C7,C8 C9,10 Part Number AIC1578CS CEM4435 AIC1085CM 47µH 1N5820 470µF 0.1µF 0.01µF 47K/ 15K/ 12K/ 750/ SO-8 SO-8 TO-263 Manufacturer Cailcraft Cailcraft Schottky Remark N-MOSFET
ANALOG INTEGRATIONS CORPORATION
Industry Road, Science-based Industrial Park Hsinchu, Taiwan, R.O.C.
www. analog.com.tw
TEL: (8863)577-2500 FAX:(8863)577-2510

High Efficiency Monitor Power Design Using AIC1578 Michael Huang

Top Searches for this datasheet

Other recent searches