BM1584 BOOKLY | Alldatasheet

Document overview

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  • PDF pages: 8

Technical content

Features

  • Wide 4V to 30V Operating Input Range
  • 3A Continuous Output Current
  • Fixed 380KHz Switching Frequency
  • No Schottky Diode Required
  • Short Protection with Hiccup-Mode
  • Built-in Over Current Limit
  • Built-in Over Voltage Protection
  • Internal Soft start
  • Output Adjustable from 0.8V
  • Integrated internal compensation
  • Thermal Shutdown
  • Available in ESOP8, SOT23 Package
  • -40°C to +85°C Temperature Range

Applications

  • CCTV Camera
  • Flat-Panel Television and Monitor
  • Battery Charger
  • Distributed Power Systems General Description The BM1584 is a high frequency, synchronous, rectified, step-down, switch-mode converter with internal power MOSFETs. It offers a very compact solution to achieve a 4A peak output current over a wide input supply range, with excellent load and line regulation. The BM1584 requires a minimal number of readily available, external components and is available in a space saving ESOP8 package. Typical Application Circuit COUTR1 CIN IN SW EN FB GND/EPAD VIN VOUT BST ON/ OFF CFFNC NC 2 3 8 6 Opt.

Figure 1. Basic Application Circuit

30V 3A 380KHz Synchronous Step-Down Regulator Pin Description Pin Configuration BST VIN SW GND FB NC EN NC (ESOP8) Pin Description Pin Name Function 1 BST Bootstrap. A capacitor connected between SW and BST pins is required to form a floating supply across the high-side switch driver.

2 VIN Power Supply Pin

3 SW Switching Pin

5 FB Adjustable V ersion Feedback input. Connect FB to the center point of the external resistor divider 6 NC 7 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. 8 NC Order Information Marking Part No. Model Description Package MOQ GLYLL 70301579 BM1584 Buck, 4-30V, 3.0A, 380KHz, VFB 0.8V, ESOP8 ESOP8 3000PCS Page 2 BM1584 BS FB EN GND IN SW BS FB EN GND IN SW BS FB EN GND IN SW SW EN IN BS FB GND TOP VIEW TOP VIEW (SOT23) TOP VIEW (SOT23)

30V 3A 380KHz Synchronous Step-Down Regulator Absolute Maximum Ratings Vin, EN, V oltage …………………... -0.3V to 36V Operating Temperature Range ….. -40°C to +85°C Lead Temperature (Soldering, 10s) ……... +300°C Thermal Resistance (θJA) ……………50 °C/W Thermal Resistance （θJC）………… 10 °C/W SW V oltage …………………… -0.3V to (VIN+0.5V) Storage Temperature Range ……… - 65°C to 150°C BS V oltage …………………….. (Vsw-0.3) to (Vsw+5V) ESD (Human Body Made) HMB …………… 2KV Note1: Exceeding these ratings may damage the device. Note2: The device is not guaranteed to function outside of its operating conditions.

Electrical Characteristics

(VIN=12V , VOUT=5V , TA = 25°C, unless otherwise noted.) Parameter Test Conditions Min Typ Max Unit Input V oltage Range 4 30 V Supply Current in Operation VEN=3.0V , VFB=1.1V 0.4 0.6 mA Supply Current in Shutdown VEN =0 or EN = GND 1 μA Regulated Feedback V oltage TA = 25°C, 4V≤VIN ≤18V 0.784 0.8 0.816 V High-Side Switch On-Resistance 130 m Ω Low-Side Switch On-Resistance 100 m Ω High-Side Switch Leakage Current VEN=0V , VSW=12V 1 uA Upper Switch Current Limit Minimum Duty Cycle 4 A Oscillation Frequency 0.38 MHz Maximum Duty Cycle VFB=0.8V 92 % Minimum On-Time 80 nS Minimum Off-Time 150 nS Soft Start 1.2 mS Thermal Shutdown 160 ℃ Thermal Hysteresis 20 ℃ Note1: 100% production test at +25°C. Specifications over the temperature range are guaranteed by design and characterization. Note2: Dynamic supply current is higher due to the gate charge being delivered at the switching frequency. Page 3 BM1584

Figure 2. BM1584 Application Circuit excellent AC and DC performance. higher than REF, REF regains control. The SS time is internally fixed to 1.2ms.

30V 3A 380KHz Synchronous Step-Down Regulator Over Current Protection & Hiccup The BM1584 has cycle-by-cycle over current limit when the inductor current peak value exceeds the set current limit threshold. Meanwhile, output voltage starts to drop until FB is below the Under-V oltage (UV) threshold, typically 25% below the reference. Once a UV is triggered, the BM1584 enters hiccup mode to periodically restart the part. This protection mode is especially useful when the output is dead-short to ground. The average short circuit current is greatly reduced to alleviate the thermal issue and to protect the regulator. The BM1584 exits the hiccup mode once the over current 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 shut 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 the Output Voltage BM1584 require an input capacitor, an output capacitor and an inductor. These components are critical to the performance of the device. BM1584 are internally compensated and do not require external components to achieve stable operation. The output voltage can be programmed by resistor divider. 𝑉𝑂𝑈𝑇 = 𝑉𝐹𝐸𝐸𝐷𝐵𝐴𝐶𝐾×𝑅1+𝑅2 VOUT R1 R2 L1MIN L1TYP L1MAX CIN COUT 12.5KΩ 50KΩ 2.2μH 2.2μH 4.7μH 20-47uF 20-68uF 1.05V 15.62KΩ 50KΩ 2.2μH 2.2μH 4.7μH 20-47uF 20-68uF 1.2V 25KΩ 50KΩ 2.2μH 2.2μH 4.7μH 20-47uF 20-68uF 1.5V 43.75KΩ 50KΩ 2.2μH 2.2μH 4.7μH 20-47uF 20-68uF 3.3V 156.25KΩ 50KΩ 3.3μH 3.3μH 4.7μH 20-47uF 20-68uF Page 5 BM1584 For BM1584S and BM1584F application

30V 3A 380KHz Synchronous Step-Down Regulator Selecting the Inductor The recommended inductor values are shown in the Application Diagram. It is important to guarantee the inductor core does not saturate during any foreseeable operational situation. The inductor should be rated to handle the peak load current plus the ripple current: Care should be taken when reviewing the different saturation current ratings that are specified by different manufacturers. Saturation current ratings are typically specified at 25°C, so ratings at maximum ambient temperature of the application should be requested from the manufacturer. OSCLin outinout f I V V V VL      ) ( Where ΔIL is the inductor ripple current. Choose inductor ripple current to be approximately 30% if the maximum load current, 3A. The maximum inductor peak current is: ) ( L LOADMAX L II I   Under light load conditions below 100mA, larger inductance is recommended for improved efficiency. Selecting the Output Capacitor Special attention should be paid when selecting these components. The DC bias of these capacitors can result in a capacitance value that falls below the minimum value given in the recommended capacitor specifications table. The ceramic capacitor’s actual capacitance can vary with temperature. The capacitor type X7R, which operates over a temperature range of −55°C to +125°C, will only vary the capacitance to within ±15%. The capacitor type X5R has a similar tolerance over a reduced temperature range of −55°C to +85°C. Many large value ceramic capacitors, larger than 1uF are manufactured with Z5U or Y5V temperature characteristics. Their capacitance can drop by more than 50% as the temperature varies from 25°C to 85°C. Therefore X5R or X7R is recommended over Z5U and Y5V in applications where the ambient temperature will change significantly above or below 25°C. Tantalum capacitors are less desirable than ceramic for use as output capacitors because they are more expensive when comparing equivalent capacitance and voltage ratings in the 0.47uF to 44uF range. Another important consideration is that tantalum capacitors have higher ESR values than equivalent size ceramics. This means that while it may be possible to find a tantalum capacitor with an ESR value within the stable range, it would have to be larger in capacitance (which means bigger and more costly) than a ceramic capacitor with the same ESR value. It should also be noted that the ESR of a typical tantalum will increase about 2:1 as the temperature goes from 25°C down to −40°C, so some guard band must be allowed. PC Board Layout Consideration PCB layout is very important to achieve stable operation. It is highly recommended to duplicate EVB layout for optimum performance. If change is necessary, please follow these guidelines and take Figure 4 for reference. 1. Keep the path of switching current short and minimize the loop area formed by Input capacitor, high-side MOSFET and low-side MOSFET. 2. Bypass ceramic capacitors are suggested to be put close to the Vin Pin. 3. Ensure all feedback connections are short and direct. Place the feedback resistors and compensation components as close to the chip as possible. 4. VOUT, SW away from sensitive analog areas such as FB. 5. Connect IN, SW, and especially GND respectively to a large copper area to cool the chip to improve thermal performance and long-term reliability. Page 6 BM1584

30V 3A 380KHz Synchronous Step-Down Regulator Package Description AAAAA TOP VIEW FRONT VIEW SIDE VIEW 0.189(4.80) 0.197(5.00) 0.150(3.80) 0.157(4. 00) 0.228(5.80) 0.244(6.20) PIN 1 ID EXAMPLE TOP MARK 0.013(0.33) 0.020(0.51) 0.050(1.27) BSC 0.051(1.30) 0.067(1.70) 0.000(0.00) 0.006(0.15) SEATING PLANE 0.0075(0.19) 0.0098(0.25) 0° ~8° GAUGE PLANE 0.010(0 .25) BSC 0.016(0.41) 0.050(1. 27) NOTE: 1. CONTROL DIM ENSION IS IN INCHES . DIMENSION IN BRACKET IS IN MILLIMETERS . 2. PACKAGE LENGTH DOES NOT INCLUDE MOLD FLASH , PROTRUSIONS OR GATE BURRS . 3. PACKAGE W ID TH DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSI ONS. 4. LE AD COPLANARITY (BOTTOM OF LEADS AFTER FORMING ) SHALL BE 0.004" INCHES MAX. 5. DRAWING CONFORMS TO JEDEC MS -012, VARIATION BA. 6. DRAWING IS NOT TO SCALE . 0.010(0.25) 0.020(0.50) x45° BOTTOM VIEW RECOMMENDED PAD LAYOUT 0.063(1.60) 0.138(3.51) 0.124(3.15) 0.136(3.45) 0.089(2.26) 0.101(2.56) ESOP8 (EXPOSED PAD) Page 7 BM1584

TOP VIEW RECOMMENDED PAD LAYOUT FRONT VIEW SIDE VIEW AAAAA 2.80 3.00 1.50 1.70 2.60 3.00 PIN 1 EXAMPLE TOP MARK 1.20 TYP 0.60 TYP 0.95 BSC 2.60 TYP 0.90 1.30 0.30 0.50 0.95 BSC

1.45 MAX

0.00 0.15 SEATING PLANE 0.09 0.20 AAAAA 2.80 3.00 1.50 1.70 2.60 3.00 PIN 1 EXAMPLE TOP MARK 1.20 TYP 0.60 TYP 0.95 BSC 2.60 TYP 0.90 1.30 0.30 0.50 0.95 BSC 0.00 0.15 SEATING PLANE 0.09 0.20 AAAAA 2.80 3.00 1.50 1.70 2.60 3.00 PIN 1 EXAMPLE TOP MARK 1.20 TYP 0.60 TYP 0.95 BSC 2.60 TYP 0.90 1.30 0.30 0.50 0.95 BSC 0.00 0.15 SEATING PLANE 0.09 0.20 SOT23-6 GAUGE PLANE

0.25 BSC

0.30 0.550° ~8° Page 8 BM1584 30V 3A 380KHz Synchronous Step-Down Regulator Package Description