BL8534 High Efficiency Low Noise PFM Step-up DC/DC Converter DESCRIPTION FEATURES BL8534 series are CMOS-based PFM stepup DC-DC Converter. The converter can start up by supply voltage as low as 0.8V, and capable of delivering maximum 200mA output current at 3.3V output with 1.8V input Voltage. Quiescent current drawn from power source is as low as 20uA. All of these features make BL8534 series be suitable for the portable devices, which are supplied by a single battery to four-cell batteries. • • • • • • To reduce the noise caused by the switch regulator, BL8534 is well considerated in circuit design and manufacture. So that the interferer to other circuits by the device is reduced greatly. • Deliver 200mA at 3.3V Output voltage with 1.8V input Voltage Low start-up voltage (when the output current is 1mA)-----------------------------0.8V Output voltage can be adjusted from 2.5V to 6.0V (In 0.1V step) Output voltage accuracy ---------------±2％ Low temperature-drift coefficient of the output voltage--------------------±100ppm/℃ Only three external components are necessary: An inductor, a Schottky diode and an output filter capacitor Low quiescent current drawn from power source-------------------------------------<20uA APPLICATIONS BL8534 integrates stable reference circuits and trimming technology, so it can afford high precision and low temperature-drift coefficient of the output voltage. • • Power Source for PDA, DSC, MP3 Player, Electronic toy and wireless mouse Power Source for a Single or Dual-cell Battery-Powered Equipments Power Source for LED BL8534 is available in SOT-89-3, SOT-23-3, SOT-23-5 and TO-92 packages that are PB free. And in 5-pin packages, such as SOT-235, the device can be switch on or off easily by CE pin, to minimize the standby supply current. • TYPICAL APPLICATION ELECTRICAL CHARACTERISTICS LC3000CC3TR33 BL8534 Output Voltage(V) 4 BL8534 3 2 VIN=1.2V VIN=1.5V VIN=2V 1 VIN=2.5V VIN=3V 0 0 www.belling.com.cn 1 200 400 600 Output Current(mA) 800 BL8534 ORDERING INFORMATION BL8534 □ 1 □ 2 □ 3 □ 4 Code Description Temperature & Rohs: C: -40~85°C, Pb Free Rohs Std. Package type: B3: SOT-23-3 B5: SOT-23-5 C3: SOT-89-3 H: TO-92 Packing type: TR: Tape & Reel (Standard) BG: Bag (TO-92) Output voltage e.g. 25=2.5V 33=3.3V 60=6.0V 1 □ 2 □ 3 □ 4 □ MARKING DESCRIPTION Product Classification BL8534CB3TR□□ Product Classification Marking Marking LD: Product Code LD: Product Code LDXZZ X: Output Voltage LDXZZ X: Output Voltage ZZ: Date Code Product Classification Marking LDXX LD: Product Code XX: Output Voltage YY: LOT NO. YYBZZ B: FAB Code ZZ: Date Code BL8534CB5TR□□ ZZ: Date Code BL8534CC3TR□□ Product Classification BL8534CHBG□□ Marking LDXX LD: Product Code XX: Output Voltage YY: LOT NO. YYBZZ B: FAB Code ZZ: Date Code LD: Product Code; X: Output voltage for SOT-23-3 and SOT-23-5; XX: Output voltage for SOT-89-3 and TO-92. 25 stands for 2.5V, 60 stands for 6.0V; Z: The Year of manufacturing, ”7” stands for year 2007, ”8” stands for year 2008; Z: The week of manufacturing. ”A” stands for week 1, ”Z” stands for week 26, ” A ” stands for week 27, ” Z ” stands for week 52. Output Voltage Code For SOT-23-3 and SOT-23-5 Vout 2.5V Code 5 Vout 3.0V Code 0 Vout 3.8V Code 8 Vout 4.5V Code 5 2.7V 7 3.3V 3 4.0V 0 5.0V 0 2.8V 8 3.6V 6 4.2V 2 6.0V 0 www.belling.com.cn 2 BL8534 ABSOLUTE MAXIMUM RATING Parameter Value Max Input Voltage CE Pin Voltage Lx Pin Output Current Lx Pin Voltage Operating Junction Temperature (TJ) Ambient Temperature (TA) Power Dissipation SOT-23-3 SOT-23-5 SOT-89-3 TO-92 Storage Temperature (Ts) Lead Temperature & Time -0.3V-10V -0.3V-(Vout+0.3) 0.7A 10V 125°C -40°C -85°C 250mW 250mW 500mW 500mW -40°C -150°C 260°C, 10Sec Note: Exceed these limits to damage to the device. Exposure to absolute maximum rating conditions may affect device reliability. RECOMMENDED WORK CONDITIONS Item Min Input Voltage Range Inductor Input Capacitor Output Capacitor Ambient Temperature 0.8 10 0 47 -40 Recommended Max. Unit Vout 100 V ≥10 85 BLOCK DIAGRAM BL8534 Note: CE pin is only available on 5 pins packages. www.belling.com.cn 3 µH µF µF °C BL8534 PIN DESCRIPTION CE Chip Enable (Active high) Vss Ground OUT Output, Power supply for internal LX Switching Pin NC Not Connected ELECTRICAL CHARACTERISTICS SYMBOL ITEM Vout_rt Rated Output Voltage Iin Input Current Vstart Start-up Voltage Vhold Hold-on Voltage IDD Rswon ILXleak Quiescent Current drawn From Power Source Switch ON Resistance LX Leakage Current CE “H” Threshold Voltage CE “L” VCEL Threshold Voltage Oscillator Fosc_max Frequency Minimum Off TOFF_MIN Time Oscillator Duty Maxdty Cycle VCEH www.belling.com.cn TEST CONDITIONS Iout=0mA， Vout=Vout*0.6 Iout=1mA， VS：0→2V Iout=1mA， VS：2→0V REFERENCE DATA Min 2.45 2.646 2.94 3.234 3.528 3.92 4.9 5.88 0.6 Without external components, Vout =Vout_rt×1.05 Max 2.55 2.754 3.06 3.366 3.672 4.08 5.1 6.12 15 20 uA 0.8 0.9 V 0.7 4 VCE：0→2V 0.5 7 5 0.3 70 4 uA V VCE： 2→0V LX on “L” side uA Ω 0.8 LX on “L” side Vout=Vout_rt*0.96 V V 0.8 Vout=VLx=6V (VCE=0V in 5 pins packages) UNIT Typ 2.5 2.7 3.0 3.3 3.6 4.0 5.0 6.0 V 150 KHz 1.4 uS 75 80 ％ BL8534 DETAILED DESCRIPTION The BL8534 series are boost structure, voltage-type Pulse-Frequency Modulation (PFM) step-up DC-DC converter. Only three external components are necessary: an inductor, an output filter capacitor and a schottky diode. And the converter’s low noise and low ripple output voltage can be adjusted from 2.5V to 5.0V, 0.1V step. By using the depletion techniques, the quiescent current drawn from power source is lower than 7uA. The high efficiency device consists of resistors for output voltage detection and trimming, a start-up voltage circuit, an oscillator, a reference circuit, a PFM control circuit, a switch protection circuit and a driver transistor. The reference circuit provides stable reference voltage to output stable output voltage. Because internal trimming technology is used, the chip output change less than ±2%. At the same time ， the problem of temperature-drift coefficient of output voltage is considered in design, so temperature-drift coefficient of output voltage is less than 100ppm/℃。 High-gain differential error amplifiers guarantees stable output voltage at difference input voltage and load. In order to reduce ripple and noise, the error amplifier is designed with high band-with. Though at very low load condition, the quiescent current of chip do affect efficiency certainly. The four main energy loss of Boost structure DC-DC converter in full load are the ESR of inductor, the voltage of Schottky diode, on resistor of internal N-channel MOSFET and its driver. In order to improve the efficiency, BL8534 integrates low onresistor N-channel MOSFET and well design driver circuits. The switch energy loss is limited at very low level. The PFM control circuit is the core of the BL8534. This block controls power switch on duty cycle to stabilize output voltage by calculating results of other blocks which sense input voltage, output voltage, output current and load conditions. In PFM modulation system, the frequency and pulse width is fixed. The duty cycle is adjusted by skipping pulses, so that switch on-time is changed based on the conditions such as input voltage, output current and load. The oscillate block inside BL8534 provides fixed frequency and pulse width wave. COMPONENTS SELECTION boost DC-DC to operate in the continuous current-mode condition. Thus it can be seen, the inductor and schottky diode affect the conversion efficiency greatly. The inductor and the capacitor also have great influence on the output ripple voltage of the converter. So it is necessary to choose a suitable inductor, a capacitor and a right schottky diode, to obtain high efficiency, low ripple and low noise. Before discussion，we define D≡ LMIN ≥ The above expression is got under conditions of continuous current mode, neglect Schottky diode’s voltage, ESR of both inductor and capacitor. The actual value is greater that it. If inductor’s value is less than Lmin ， the efficiency of DC-DC converter will drop greatly, and the DC-DC circuit will not be stable. VOUT − VIN VOUT INDUCTOR SELECTION Above all, we should define the minimum value of the inductor that can ensure the www.belling.com.cn D( 1 − D)2 RL 2f Secondly, consider the ripple of the output voltage, 5 BL8534 ∆I = CAPACITOR SELECTION DVIN Lf I MAX = Ignore ESR of capacitor，the ripple of output voltage is: VIN DVIN + 2 (1 − D) RL 2 Lf r= If inductor value is too small, the current ripple through it will be great. Then the current through diode and power switch will be great. Because the power switch on chip is not ideal switch, the energy of switch will improve. The efficiency will fall. So large value capacitor is needed to reduce ripple. But too large capacitor value will slow down system reaction and cost will improve. So 100uF capacitor is recommended. Larger capacitor value will be used in large output current system. If output current is small (<10mA), small value is needed. Thirdly，in general, smaller inductor values supply more output current while larger values start up with lower input voltage and acquire high efficiency. Consider ESR of capacitor ， ripple will increase： An inductor value of 3uH to 1mH works well in most applications. If DC-DC converter delivers large output current (for example: output current is great than 50mA), large inductor value is recommended in order to improve efficiency. If DC-DC must output very large current at low input supply voltage, small inductor value is recommended. r' = r + DIODE SELECTION rL Rload (1 − D) 2 Rectifier diode will affects efficiency greatly， Though a common diode (such as 1N4148) will work well for light load ， it will reduce about 5%~10% efficiency for heavy load ， For optimum performance, a Schottky diode (such as 1N5817 、 1N5819 、 1N5822) is recommended. For example: input 1.5V, output is 3.0V, Rload=20Ω, rL=0.5Ω, the energy loss is 10%. Consider all above，inductor value of 47uH、 ESR<0.5Ω is recommended in most applications. Large value is recommended in high efficiency applications and smaller value is recommended www.belling.com.cn I MAX RESR VOUT When current is large, ripple caused by ESR will be main factor. It may be greater than 100mV。The ESR will affect efficiency and increase energy loss. So low-ESR capacitor (for example: tantalum capacitor) is recommend or connects two or more filter capacitors in parallel. The ESR of inductor will affect efficiency greatly. Suppose ESR value of inductor is rL，Rload is load resistor，then the energy can be calculated by following expression ： ∆η ≈ ∆VOUT D = VOUT RLOAD Cf 6 BL8534 TEST CIRCUITS BL8534 Figure 1: Output voltage test circuit (IOUT=1mA) BL8534 Figure 2: Start-up voltage test circuit (IOUT =1mA) BL8534 Figure 3: Hold-on voltage test circuit (IOUT =1mA) BL8534 Figure 4: Quiescent current test circuit (VS=Vout_rt*1.05，R=1KΩ，C=0.1uF) BL8534 Figure 5: Oscillator frequency and duty cycle test circuit (VS=Vout_rt*0.95，R=1KΩ) www.belling.com.cn 7 BL8534 TYPICAL PERFORMANCE CHARACTERISTICS Recommended operating conditions: Cin=47uF, Cout=100uF, Topt=25°C. (Unless otherwise noted) And all the tests below are made on BL8534CC3TR33. Quiescent Current VS Input Voltage Quiescent Current VS Input Voltage 50 Quiescent Current(uA) Quiescent Current(uA) 50 40 30 L=10uH 20 10 40 30 L=47uH 20 10 0 0 1 1.5 2 2.5 1 3 1.5 Input Voltage(V) 3 4 Output Voltage(V) 4 Output Voltage(V) 2.5 Output Voltage VS Output Current Output Voltage VS Output Current 3 VIN=1.2V 2 VIN=1.5V L=10uH VIN=2V 1 VIN=2.5V 0 200 400 600 3 VIN=1.2V 2 VIN=1.5V L=47uH VIN=2V 1 VIN=2.5V VIN=3V 0 VIN=3V 0 0 800 200 400 600 800 Output Current(mA) Output Current(mA) Efficiency VS Load Current Efficiency VS Load Current 100% 100% Efficiency(%) 80% Efficiency(%) 2 Input Voltage(V) 60% VIN=1.2V 40% VIN=1.5V L=10uH VIN=2V 20% 80% 60% VIN=1.2V L=47uH 40% VIN=1.5V VIN=2V VIN=2.5V 20% VIN=3V VIN=2.5V 0% VIN=3V 0% 1 10 100 1 1000 Load Current(mA) www.belling.com.cn 10 100 Load Current(mA) 8 1000 BL8534 TYPICAL PERFORMANCE CHARACTERISTICS (Continued) Recommended operating conditions: Cin=47uF, Cout=100uF, Topt=25°C. (Unless otherwise noted) And all the tests below are made on BL8534CC3TR33. Output Ripple VS Load Current Output Ripple VS Load Current 250 Output Ripple(mV) Output Ripple(mV) 100 80 60 VIN=1.2V L=10uH VIN=1.5V 40 VIN=2V VIN=2.5V 20 VIN=3V 150 VIN=1.2V L=47uH 100 VIN=1.5V VIN=2V 50 VIN=2.5V VIN=3V 0 0 200 400 600 0 800 0 Load Current(mA) 1.0 0.8 0.6 0.4 L=47uH 0.2 L=10uH 0.0 0 5 10 15 20 Output Current(mA) www.belling.com.cn 100 200 300 400 500 Load Current(mA) Minimum Start Up Voltage VS Output Current Input Voltage(V) 200 9 600 700 BL8534 PACKAGE LINE Package SOT-23-3 Devices per reel 3000Pcs Unit mm Devices per reel 3000Pcs Unit mm Package dimension： Package SOT-23-5 Package specification： www.belling.com.cn 10 BL8534 PACKAGE LINE (Continued) Package SOT-89-3 Devices per reel 1000Pcs Unit mm Devices per Bag 1000Pcs Unit mm Package Dimension: Package TO-92 Package Dimension: www.belling.com.cn 11