BL8033 BELLING | Alldatasheet
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Technical content
www.belling.com.cn 1 500KHz, 16V, 3A Synchronous Step-Down Converter BL8033
DESCRIPTION
The BL8033 is a fully integrated, high -efficiency 3A synchronous rectified step -down converter. The BL8033 operates at high efficiency over a wide output current load range. This device offers two operation modes, PWM control and PFM Mode switching control, which allows a high efficiency over the wider range of the load. The BL8033 requires a minimum number of readily available standard external components and is available in a 6-pin SOT23 ROHS compliant package.
FEATURES
High Efficiency: Up to 96% 500KHz Frequency Operation 3A Output Current No Schottky Diode Required 4.2V to 16V Input Voltage Range 0.8V Reference Slope Compensated Current Mode Control for Excellent Line and Load Transient Response Integrated internal compensation Stable with Low ESR Ceramic Output Capacitors Over Current Protection with Hiccup-Mode Thermal Shutdown Inrush Current Limit and Soft Start Available in SOT23-6 -40° C to +85° C Temperature Range
APPLICATIONS
Distributed Power Systems Digital Set Top Boxes Flat Panel Television and Monitors Wireless and DSL Modems Notebook Computer TYPICAL APPLICATION VIN EN BST SW FB GND VIN VOUTC1 22uF 1uF L 4.7uH 40.2k 13k 22uF LC2333 R3 10k 3.3V/3ARen 100k Note: 1) C1 and C2 recommended using 22uF ceramic capacitors. If the electrolytic capacitor is used, it is recommended that the ceramic capacitor in parallel with a capacitance value of 0.1uF or more. 2) The resistance R3 in Figure 1 makes the loop more stable. If it isn ’t used, the resistance R1、R2 should be adjusted(See Figure2.). The value of R1 is recommended to be about 300kΩ. 3) C3 can be valued as 1uF, 0.1uF. Figure 1. Figure 2.
www.belling.com.cn 2 BL8033
ORDERING INFORMATION
GN: Product Code YW: Date code (Year & Week) Product ID BL8033CB6TR Devices per reel 3000 ABSOLUTE MAXIMUM RATING Parameter Value Supply Voltage VIN -0.3V to 17V Switch Node Voltage VSW -0.3V to (VIN+0.5V) Boost Voltage VBST VSW-0.3V to VSW+5V Enable Voltage VEN -0.3V to 17V All Other Pins -0.3V to 6V Operating Temperature Range -40C to 85C Storage Temperature Range -65C to 150C Lead Temperature (Soldering, 10s) 300C
ELECTRICAL CHARACTERISTICS
(VIN=12V, VOUT=5V, TA=25C, unless otherwise stated) Parameter Conditions Min Typ Max Unit Input Voltage Range 4.2 16 V UVLO Threshold 4.1 V Supply Current in Operation VEN = 2.0V, VFB = 1.1V 0.5 mA Supply Current in Shutdown VEN = 0V or VEN = GND 5 10 uA Regulated Feedback Voltage 4.2V≤VIN ≤16V 0.784 0.8 0.816 V High-side Switch On Resistance VBST-SW = 5V 120 m Ω Low-side Switch On Resistance VIN = 5V 60 m Ω High-side Switch Leakage Current VEN = 0V, VSW = 0V 0 10 uA Upper Switch Current Limit Minimum Duty Cycle 6 A Oscillation Frequency 500 KHz Maximum Duty Cycle VFB = 0.7V 92 % Minimum On Time 100 ns EN Input Voltage “H” 1.5 V EN Input Voltage “L” 0.6 V Thermal Shutdown 160 °C PIN DESCRIPTION PIN # NAME DESCRIPTION
1 GND Ground
2 SW Switching Pin
3 VIN Power supply Pin
4 FB Adjustable version feedback input. Connect FB to the center point of the external resistor divider. 5 EN Drive this pin to a logic-high to enable the IC. Drive to a logic-low to disable the IC and enter micro-power shutdown mode. 6 BST Boostrap. A capacitor connected between SW and BST pins is required to form a floating supply across the high-side switch driver.
www.belling.com.cn 3 BL8033 ELECTRICAL PERFORMANCE Tested under, L=4.7uH, TA=25C, unless otherwise specified 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Efficiency(%) Iout (A) Efficiency vs. Iout (Vout=1.2V) Vin=5V Vin=12V Vin=16V 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Efficiency(%) Iout (A) Efficiency vs. Iout (Vout=5.0V) Vin=6V Vin=12V Vin=16V 3.00 3.05 3.10 3.15 3.20 3.25 3.30 3.35 3.40 3.45 3.50 0.0 1.0 2.0 3.0 Vout (V) Iout (A) Vout vs. Iout (Vout=3.3V) Vin=5V Vin=6V Vin=12V Vin=16V 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Efficiency(%) Iout (A) Efficiency vs. Iout (Vout=3.3V) Vin=5V Vin=6V Vin=12V Vin=16V 0.90 0.95 1.00 1.05 1.10 1.15 1.20 1.25 1.30 0.0 1.0 2.0 3.0 Vout (V) Iout (A) Vout vs. Iout (Vout=1.2V) Vin=5V Vin=12V Vin=16V 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 5.0 5.1 5.2 5.3 5.4 5.5 Vout (V) Iout (A) Vout vs. Iout (Vout=5.0V) Vin=6V Vin=12V Vin=16V
www.belling.com.cn 4 BL8033 Load Transient Vin=12V, Vout=3.3V, Iout=0.01~3A Ch2—Vout, Ch4--IL Load Transient Vin=12V, Vout=3.3V, Iout=0.5~3A Ch2—Vout, Ch4--IL BLOCK DIAGRAM 88% 89% 90% 91% 92% 93% 94% 95% 96% 97% 98% 6 8 10 12 14 16 Efficiency(%) Vin (V) Efficiency vs. Vin Iout=1A Vout=3.3V 3.10 3.15 3.20 3.25 3.30 3.35 3.40 6 8 10 12 14 16 Vout (V) Vin(V) Vout vs. Vin Iout=1A
www.belling.com.cn 5 BL8033 DETAILED DESCRIPTION Internal Regulator The BL8033 is a current mode step down DC/DC converter that provides excellent transient response with no extra external compensation components. This device contains an internal, low resistance, high voltage power MOSFET, and operates at a high 500K operating frequ ency to ensure a compact, high efficiency design with excellent AC and DC performance. Error Amplifier The error amplifier compares the FB pin voltage with the internal FB reference (V FB) and outputs a current proportional to the difference between the two. This output current is then used to charge or discharge the internal compensation network to form the COMP voltage, which is used to control the power MOSFET current. The optimized internal compensation network minimizes the external component counts and simplifies the control loop design. Internal Soft-Start The soft -start is important for many applications because it eliminates power -up initialization problems. The controlled voltage ramp of the output also reduces peak inrush current during start-up, minimizing start-up transient events to the input power bus. Over-Current-Protection and Hiccup The BL8033 has a cycle -by-cycle over -current limit for when the inductor current peak value exceeds the set current -limit threshold. First, when the output voltage drops until FB falls below the Under -Voltage (UV) threshold (typically 140mV) to trigger a UV event, the BL8033 enters hiccup mode to periodically restart the part. This protection mode is especially useful when the output is dead -shorted to ground. This greatly reduces the average short-circuit current to alleviate thermal issues and to protect the regulator. The BL8033 exits hiccup mode once the overcurrent condition is removed. Startup and Shutdown If both VIN and EN are higher than their appropriate thresholds, the chip starts. The reference block starts first, generating stable reference voltage and currents, and then the internal regulator is enabled. The regulator provides stable supply for the remaining circuitries. Three events can sh ut down the chip: EN low, VIN low and thermal shutdown. In the shutdown procedure, the signaling path is first blocked to avoid any fault triggering. The COMP voltage and the internal supply rail are then pulled down. The floating driver is not subject to this shutdown command. APPLICATIONS INFORMATION Setting Output Voltages The external resistor divider is used to set the output voltage (see Typical Application on page 1). The feedback resistor R1 also sets the feedback loop bandwidth with the internal compensation capacitor. Choose R1 to be around 300kΩ for optimal transient response. R2 is then given by: Selecting the Inductor Use a 2.2μH-to-10μH inductor with a DC current rating of at least 25% percent higher than the maximum load current for most applications. For highest efficiency, select an inductor with a DC resistance less than 15mΩ. For most designs, derive the inductance value from the following equation. Where ΔIL is the inductor ripple current. Choose an inductor current approximately 30% of the maximum load current. The maximum inductor peak current is: Under light-load conditions (below 100mA), use a larger inductor to improve efficiency.
www.belling.com.cn 6 BL8033 Selecting the Output Capacitor The output capacitor (C2) maintains the DC output voltage. Use ceramic, tantalum, or low - ESR electrolytic capacitors. Use low ESR capacitors to limit the output voltage ripple. Estimate the output voltage ripple with: Where L is the inductor value and R ESR is the equivalent series resistance (ESR) of the output capacitor. For ceramic capacitors, the capacitance dominates the impedance at the switching frequency and causes most of the output voltage ripple. For simplification, e stimate the output voltage ripple with: For tantalum or electrolytic capacitors, the ESR dominates the impedance at the switching frequency. For simplification, the output ripple can be approximated with: The characteristics of the output capacitor also affect the stability of the regulation system. The BL8033 can be optimized for a wide range of capacitance and ESR values. PC BOARD LAYOUT PCB layout is very important to achieve stable operation. For best results, use the following guidelines and figures as reference. 1) Keep the connection between the input ground and GND pin as short and wide as possible. 2) Keep the connection between the input capacitor and VIN pin as short and wide as possible. 3) Use short and direct feedback connections. Place the feedback resistors and compensation components as close to the chip as possible. 4) Route SW away from sensitive analog areas such as FB.
www.belling.com.cn 7 BL8033 TYPICAL APPLICATION CIRCUITS Figure3. 12V VIN, 5V/3A Figure4. 12V VIN, 3.3V/3A Figure5. 12V VIN, 2.5V/3A BL8033 BL8033 BL8033
www.belling.com.cn 8 BL8033 Figure6. 12V VIN, 1.8V/3A Figure7. 12V VIN, 1.2V/3A PACKAGE OUTLINE Package specification： BL8033 BL8033