BL9328 1.5 MHz, Dual 800mA Synchronous Buck Converter FEATURES • • • • • • • • • • • • • DESCRIPTION High Efficiency: Up to 96% 1.5MHz Constant Switching Frequency Current Mode Operation for Excellent Line and Load Transient Response No Schottky Diode Required 2.5V to 5.5V Input Voltage Range Adjustable Output Voltage 100% Duty Cycle in Dropout Mode Output Current:Up to 800mA per Channel Low Quiescent Current: 180μA each Over temperature Protection Short Circuit Protection Shutdown Quiescent Current < 1μA Compact and thermally enhanced Package:ESOP-8 APPLICATIONS • • • • • • • • Cellular and Smart Phones Wireless Handsets and DSL Modems Microprocessors and DSP Core Supplies PDAs Digital Still and Video Cameras MP3/MP4/MP5 Players Portable Instruments GPS Receivers ORDERING INFORMATION The BL9328 is a dual constant frequency, 1.5MHz, slope compensated current mode PWM step-down converter working under an input voltage range of 2.5V to 5.5V. This feature makes the BL9328 suitable for single cell Li-ion battery-powered applications. The internal synchronous rectifier is desired to increase efficiency without an external Schottky diode. 100% duty cycle capability extends battery life in portable devices, while the quiescent current is 180μA at no load, and drops to < 1μA in shutdown. Pulse Skipping Mode operation increases efficiency at light loads, further extending battery life. Low output voltage ripple and small external inductor and capacitor sizes are achieved with 1.5MHz switching frequency. The BL9328 is offered in a compact and thermally enhanced ESOP-8 package, and is available in an adjustable version. TYPICAL APPLICATION BL9328 – X XXXX Package： ESPA: ESOP-8-A ESPB: ESOP-8-B Features: P: Standard (default, lead free) C: Customized Figure 1. BL9328-ADJ Typical Application Circuit PPMIC BU BL9328 Rev 0.3 6/2010 www.belling.com.cn Belling Proprietary Information. Unauthorized Photocopy and Duplication Prohibited ©2010 Belling All Rights Reserved 1 BL9328 1.5 MHz, Dual 800mA Synchronous Buck Converter Absolute Maximum Rating (Note1) Input Supply Voltage(IN1,IN2)………-0.3V to +6V EN1,EN2,VFB1,VFB2 Voltages………-0.3V to +VIN SW1,SW2 Voltages……………-0.3V to (VIN+0.3V) P-Channel Switch Source Current (DC) ………1A N-Channel Switch Sink Current (DC) …………1A Peak SW Sink and Source Current……………1.4A Operating Temperature Range……-40°C to +85°C Junction Temperature (Note2) ………………+125°C Storage Temperature Range………-65°C to +150°C Lead Temperature (Soldering, 10s) ………+300°C Package Information ESOP-8-B ESOP-8-A IN1 1 SW1 2 IN2 3 SW2 4 Part Number BL9328 Y Year 9 GND Top Mark BL9328 A Y W W (Note3) 8 FB1 7 EN1 6 FB2 IN2 3 5 EN2 SW2 4 IN1 SW1 2 Part Number Temp Range BL9328 -40°C to +85°C 9 2009 A 2010 B 2011 C 2012 D 2013 01 1 … … 09 9 10 10 11 11 WW Week 1 … … 9 GND 8 EN1 7 FB1 6 EN2 5 FB2 Top Mark BL9328 B Y W W(Note3) 51 51 Temp Range -40°C to +85°C 52 52 Thermal Resistance (Note 4) Package ESOP-8 ӨJA 50°C/W ӨJC 10°C/W Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: TJ is calculated from the ambient temperature TA and power dissipation PD according to the following formula: TJ = TA + (PD) x (50°C/W). Note 3: A B: Package Type (A: ESOP-8-A, B: ESOP-8-B) Y: Year of wafer manufacturing W W: Week of wafer manufacturing Note 4: Thermal Resistance is specified with approximately 1 square of 1 oz copper. PPMIC BU BL9328 Rev 0.3 6/2010 www.belling.com.cn Belling Proprietary Information. Unauthorized Photocopy and Duplication Prohibited ©2010 Belling All Rights Reserved 2 BL9328 1.5 MHz, Dual 800mA Synchronous Buck Converter Pin Description NAME IN1,IN2 SW1,SW2 EN1,EN2 FB1,FB2 GND FUNCTION Supply Input Pin. Must be closely decoupled to GND with a 2.2µF or greater ceramic capacitor. Power Switch Output. It is the switch node connection to external inductor. This pin connects to the drains of the internal P-Channel and N-Channel MOSFET switches. Regulator Enable Control Input. Drive EN above 1.5V to turn on the part. Drive EN below 0.3V to turn it off. In shutdown, all functions are disabled drawing <1µA supply current. Do not leave EN floating. Feedback Input Pin. Connect FB to the center point of the external resistor divider. The regulated voltage on this pin is 0.6V. Power Ground Pin. Block Diagram ESOP-8-A ESOP-8-B PPMIC BU BL9328 Rev 0.3 6/2010 www.belling.com.cn Belling Proprietary Information. Unauthorized Photocopy and Duplication Prohibited ©2010 Belling All Rights Reserved 3 BL9328 1.5 MHz, Dual 800mA Synchronous Buck Converter Electrical Characteristics (Note5) (VIN1 = VIN2=VEN1= VEN2= 3.6V, TA = 25°C, unless otherwise noted.) Parameter Conditions Input Voltage Range Input DC Supply Current Active Mode VFB=0.5V or VOUT=90% Shutdown Mode VFB=0V, VIN=4.2V TA = +25°C Regulated Feedback TA= 0°C ≤ TA ≤ 85°C Voltage TA= -40°C ≤ TA ≤ 85°C VFB Input Bias Current Reference Voltage Line Regulation Output Overvoltage Lockout Output Voltage Line Regulation Output Voltage Load Regulation TYP MAX Unit 5.5 V 300 1.0 0.6120 0.6135 0.6150 µA ±30 nA 0.04 0.4 %/V 50 80 mV 0.04 0.40 % 2.5 0.5880 0.5865 0.5850 180 0.1 0.6000 0.6000 0.6000 VFB = 0.65V VIN = 2.5V to 5.5V ∆VOVL = VOVL – VFB, Adjustable Version 20 VIN = 2.5V to 5.5V Oscillator Frequency RDS(ON) of P-CH MOSFET VIN=3V, VFB=0.5V or VOUT=90% Duty Cycle <35% VFB=0.6V or VOUT=100% ISW = 300mA RDS(ON) of N-CH MOSFET Peak Inductor Current MIN 1.2 V 0.5 % 1.2 A 1.5 0.40 1.8 0.50 MHz Ω ISW = -300mA 0.35 0.45 Ω SW Leakage Current VRUN = 0V, VSW= 0V or 5V, VIN = 5V ±0.01 ±1 µA EN Threshold EN Leakage Current -40°C ≤ TA ≤ 85°C 1.1 ±0.01 1.30 ±1 V µA 0.3 Note 5: 100% production test at +25°C. Specifications over the temperature range are guaranteed by design and characterization. PPMIC BU BL9328 Rev 0.3 6/2010 www.belling.com.cn Belling Proprietary Information. Unauthorized Photocopy and Duplication Prohibited ©2010 Belling All Rights Reserved 4 BL9328 1.5 MHz, Dual 800mA Synchronous Buck Converter Typical Performance Characteristics (Test Figure 1 above unless otherwise specified) Efficiency vs. Output Current Output Voltage vs. Load Current 2.2 90 VOUT=1.8V L=2.2uH 80 2.0 Output Voltage(V) Efficiency(%) VIN=3.6V TA=25°C 2.1 70 60 50 40 20 0.1 1 10 100 1.8 1.7 1.6 1.5 Vin=2.7V Vin=3.6V Vin=4.2V 30 1.9 1.4 1.3 1000 0 200 400 Output Current(mA) 800 1000 1200 Output Voltage vs. Input Voltage Reference Voltage vs. Temperature 0.606 1.820 VIN=3.6V ILOAD=10mA ILOAD=100mA ILOAD=600mA 1.815 0.605 1.810 VOUT(V) Reference Voltage(V) 600 Load Current(mA) 0.604 1.805 1.800 1.795 0.603 1.790 1.785 0.602 -50 -25 0 25 50 75 100 125 1.780 2.7 3.0 3.3 3.6 3.9 4.2 4.5 4.8 5.1 Temperature(°C) VIN(V) Supply Current vs. Supply Voltage Start_up from Shutdown 5.4 5.7 245 VOUT=1.8V ILOAD=0A TA=25°C Dynamic Supply Current(uA) 240 235 230 225 220 215 210 205 200 195 2 3 4 5 6 Supply Voltage(V) PPMIC BU BL9328 Rev 0.3 6/2010 www.belling.com.cn Belling Proprietary Information. Unauthorized Photocopy and Duplication Prohibited ©2010 Belling All Rights Reserved 5 BL9328 1.5 MHz, Dual 800mA Synchronous Buck Converter Load Step Load Step Load Step Load Step Pulse Skipping Mode PPMIC BU BL9328 Rev 0.3 6/2010 Output Short www.belling.com.cn Belling Proprietary Information. Unauthorized Photocopy and Duplication Prohibited ©2010 Belling All Rights Reserved 6 BL9328 1.5 MHz, Dual 800mA Synchronous Buck Converter Operation The BL9328 uses a constant frequency, current mode step-down architecture. Both the main switch (P-channel MOSFET) and the synchronous rectifier (N-channel MOSFET) are integrated internally. This Step-Down DC-DC Converter can supply 800mA output current over a wide input voltage range from 2.5V to 5.5V. The over voltage comparator OVDET guards against transient overshoots >7.8% by turning the main switch off and keeping it off until the fault is removed. value of the output voltage, the BL9328 will keep the main switch on for more than one switching cycle and increases the duty cycle (Note 6) until it reaches 100%. The output voltage then is the input voltage minus the voltage drop across the main switch and the inductor. At low input supply voltage, the RDS(ON) of the P-Channel MOSFET increases, and the efficiency of the converter decreases. Caution must be exercised to ensure the heat dissipated not to exceed the maximum junction temperature of the IC. Note 6: The duty cycle D of a step-down converter is defined as: D = TON × f OSC × 100% ≈ Current Mode PWM Control Slope compensated current mode PWM control provides stable switching and cycleby-cycle current limit for excellent load and line responses. During normal operation, the internal main switch is turned on for a certain time to ramp the inductor current at each rising edge of the internal oscillator, and turned off when the peak inductor current reaches the controlled value. When the main switch is off, the synchronous rectifier will be turned on immediately and stay on until either the inductor current starts to reverse, as indicated by the current reversal comparator, IRCMP, or the beginning of the next clock cycle. VOUT ×100% VIN where TON is the main switch on time, and fOSC is the oscillator frequency (1.5MHz). Short Circuit Protection The BL9328 has short circuit protection. When output is shorted to ground, the oscillator frequency is reduced to prevent the inductor current from increasing beyond the PFET current limit. The PFET current limit is also reduced to lower the short circuit current. The frequency and current limit will return to the normal values once the short circuit condition is removed and the feedback voltage reaches 0.6V. Pulse Skipping Mode Operation At very light loads, the BL9328 will automatically enter Pulse Skipping Mode to increase efficiency, further extending battery life. In this mode, the control loop skips PWM pulses while maintaining output in regulation, and the switching frequency depends on the load condition. This is a kind of PFM mode operation. Maximum Load Current The BL9328 will operate with input supply voltage as low as 2.5V, however the maximum load current decreases at lower input voltage due to large IR drop on the main switch and synchronous rectifier. Dropout Operation When the input voltage decreases toward the PPMIC BU BL9328 Rev 0.3 6/2010 www.belling.com.cn Belling Proprietary Information. Unauthorized Photocopy and Duplication Prohibited ©2010 Belling All Rights Reserved 7 BL9328 1.5 MHz, Dual 800mA Synchronous Buck Converter Application Information Input Capacitor Selection Setting the Output Voltage The input capacitor reduces the surge current drawn from the input and switching noise from the device. The input capacitor impedance at the switching frequency shall be less than input source impedance to prevent high frequency switching current passing to the input. In continuous mode, the source current of the main switch is a square wave of duty cycle VOUT/VIN. To prevent large voltage transients, a low ESR input capacitor sized for the maximum RMS current must be used. The maximum RMS capacitor current is given by: Figure 1 above shows the basic application circuit with BL9328 adjustable output version. The external resistor sets the output voltage according to the following equation: R2 ) R1 Table 1—Resistor Selection vs. Output Voltage Setting VOUT R1 R2 1.0V 180 kΩ(1%) 120 kΩ(1%) 1.2V 180 kΩ(1%) 180 kΩ(1%) 1.5V 180 kΩ(1%) 270 kΩ(1%) 1.8V 180 kΩ(1%) 360 kΩ(1%) 2.5V 158 kΩ(1%) 499 kΩ(1%) 3.3V 180 kΩ(1%) 810 kΩ(1%) VOUT = 0.6V × (1 + Inductor Selection The output inductor is selected to limit the ripple current to some predetermined value, typically 20%~40% of the full load current at the maximum input voltage. In continuous mode, the ripple current is determined by: V 1 ΔI L = VOUT (1 − OUT ) f ×L VIN A reasonable starting point for setting ripple current is ∆IL=320mA (40% of 800mA). For output voltages above 2.0V, when efficiency at light load condition is important, the minimum recommended inductor is 2.2µH. For optimum voltage-positioning load transients, choose an inductor with DC series resistance below 150mΩ. For higher efficiency at heavy loads (above 200mA), or minimal load regulation (but some transient overshoot), the resistance should be kept below 100mΩ. The DC current rating of the inductor should be at least equal to the maximum load current plus half the ripple current to prevent core saturation. Thus, a 960mA rated inductor should be enough for most applications (800mA+160mA). PPMIC BU BL9328 Rev 0.3 6/2010 I RMS ≈ I OMAX [VOUT (VIN − VOUT )]0.5 VIN This formula has a maximum at VIN =2VOUT, where IRMS = IOUT/2. This simple worst-case condition is commonly used for design because even significant deviations do not offer much relief. Ceramic capacitors with X5R or X7R dielectrics are recommended due to their low ESR and high ripple current. Output Capacitor Selection The output capacitor is required to keep the output voltage ripple small and to ensure regulation loop stability. The output capacitor must have low impedance at the switching frequency. Ceramic capacitors with X5R or X7R dielectrics are recommended due to their low ESR and high ripple current. The output ripple ΔVOUT is determined by: ΔVOUT ≤ ⎞ VOUT×(VIN −VOUT) ⎛ 1 ⎟ ×⎜⎜ ESR+ VIN × fOSC× L ⎝ 8× fOSC×C2 ⎟⎠ Layout Considerations When laying out the printed circuit board, the following checklist should be used to ensure proper operation of the BL9328. Check the following in your layout: 1. The power traces, consisting of the GND trace, the SW trace and the VIN trace should be kept short, direct and wide. www.belling.com.cn Belling Proprietary Information. Unauthorized Photocopy and Duplication Prohibited ©2010 Belling All Rights Reserved 8 BL9328 1.5 MHz, Dual 800mA Synchronous Buck Converter 2. Does the VFB pin connect directly to the feedback resistors? The resistive divider R1/R2 must be connected between the (+) plate of COUT and ground. 3. Does the (+) plate of CIN connect to VIN as closely as possible? This capacitor PPMIC BU BL9328 Rev 0.3 6/2010 provides the AC current to the internal power MOSFETS. 4. Keep the switching node, SW, away from the sensitive VFB node. 5. Keep the (-) plates of CIN and COUT as close as possible. www.belling.com.cn Belling Proprietary Information. Unauthorized Photocopy and Duplication Prohibited ©2010 Belling All Rights Reserved 9 BL9328 1.5 MHz, Dual 800mA Synchronous Buck Converter Package Description Symbol A A1 A2 A3 b b1 c c1 D E E1 e L L1 Θ D1 E2 Dimensions In Millimeters Min NOM 0.08 1.2 0.55 0.39 0.38 0.21 0.19 4.7 5.8 3.7 0.18 1.4 0.65 0.5 0.41 0.2 4.9 6 3.9 1.27BSC 0.65 1.05BSC 0 Max 1.77 0.28 1.6 0.75 0.48 0.43 0.26 0.21 5.1 6.2 4.1 0.8 8° 3.30REF 2.40REF ESOP-8 Surface Mount Package PPMIC BU BL9328 Rev 0.3 6/2010 www.belling.com.cn Belling Proprietary Information. Unauthorized Photocopy and Duplication Prohibited ©2010 Belling All Rights Reserved 10