BM4115 BOOKLY | Alldatasheet
Document overview
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- PDF pages: 8
Technical content
Features
- Wide 6V to 40V Operating Input Range
- 1.2A Continuous Output Current
- Maximum 1MHz Switching Frequency
- Over Temperature Protection
- Inherent Open-Circuit LED Protection
- High-side Current Sense
- Hysteretic Control: No Compensation
- 400mΩ Low RDS(ON) Internal Power MOSFETs
- High efficiency (up to 98%)
- Adjustable Constant LED current
- PWM and Analog Dimming
- Typical 5% Output Current Accuracy
- Available in SOT89-5 Package
- -40° C to +85° C Temperature Range
Applications
- Low voltage halogen replacement LEDs
- Automotive/Decorative LED Lighting
- Low-Voltage Halogen Replacement
- Signs/Emergency Lighting
- LED Backlighting
- SELV Lighting General Description The BM4115 is step-down regulator for dimmable LED driver, which is designed in continuous current mode for driving the high-brightness LEDs from a wide input voltage of 6V to 40V . The BM4115 employs a hysteretic control scheme to regulate LED current. Moreover, the control scheme provides optimal loop stabilization and a very quick response time. The BM4115 implements PWM and analog dimming together on the EN/DIM pin. The BM4115 includes under-voltage lockout and thermal overload protection to prevent damage in the event of an output overload. The BM4115 requires a minimal number of readily available, external components and is available in a space saving SOT89-5 package. Typical Application Circuit CIN 100μF IN RS EN/DIM GND VIN 6V-40V SW RS 0.1Ω L1 68μH D AC 12V-18V Basic Application Circuit
http://www.bookly.com/ 40V 1.2A Step-Down Dimmable LED Driver Pin Description Pin Configuration RS INSW GND EN/DIM TOP VIEW SOT89-5 Exposed Pad Top Marking: JBYLL (device code: JB, Y=year code, LL= lot number code) Pin Description Pin Name Function 1 SW Drain of Internal MOSFET. Connect the inductor common terminal and Schottky anode to this pin. 2 GND Ground.
3 EN/DIM
Enable/Dimming Command Input. For PWM dimming, apply a square wave signal to this pin. For analog dimming, apply a 0.3V-to-2.5V DC voltage to linearly control the LED current range from 25% to 100%. Turn off the output current when pulling this pin below 0.3V. 4 RS LED Current Sense Input. Connect a current -sense resistor to program the LED average current to IN pin. 5 IN Input Supply Pin. Connect an appropriate decoupling capacitor from the IN pin to GND. Order Information Marking Part No. Model Description Package MOQ JBYLL 70380010 BM4115 BM4115 dimmable LED driver IC, 40V , 1.2A, SOT89-5 SOT89-5 3000PCS
http://www.bookly.com/ 40V 1.2A Step-Down Dimmable LED Driver Absolute Maximum Ratings (1)(2) Storage Temperature Range………….….. -65° C to 150° C Power Dissipation (PD) @TA=25° C SOT89-5…...…1.5W Note1: Exceeding these ratings may damage the device. Note2: The device is not guaranteed to function outside of its operating conditions. Recommended Operation Conditions
Electrical Characteristics
(VIN = 24V , TJ =-40° C to 125° C (4), unless otherwise noted.) Parameter Symbol Test Conditions Min Typ. Max Unit Input V oltage Range VIN 6.0 40.0 V IN UVLO Rising Threshold VUVLO VIN Rising 5.3 5.9 V Under-V oltage Lockout Hysteresis VUVLO_HYS 500 mV Shutdown Supply Current ISD 90 150 µA Feedback Reference V oltage (with respect to VIN) VIN-VCS 94 100 106 mV Feedback Min Reference V oltage VFB_MIN 92 108 mV EN/DIM Input High V oltage VEN_HIGH 2.5 V EN/DIM Input Low Voltage VEN_LOW 0.3 V EN/DIM Pull-Up Resistor REN 200 kΩ EN/DIM internal supply voltage VDIM EN/DIM floating 4 V Switch On Resistance RDS ON 0.4 Ω Continuous SW current ISW 1.2 A SW leakage current ILEAK 0.5 5 μA Thermal Shutdown (3) TSD 160 °C Thermal Hysteresis (3) THYS 20 °C Note3: Guaranteed by design Note4: Not test in production, guaranteed by characterization. Typical value represents the most likely parametric norm at +25°C
http://www.bookly.com/ 40V 1.2A Step-Down Dimmable LED Driver Functional Block Diagram 1.275V Reference D DIM/EN HV Regulator Driver Filter High Side Current Sense RSENSE L CIN GND SW RSIN PWM Enable 0.2V DIM VIN BM4115 Block Diagram Operation Steady State The BM4115 is a hysteretic-controlled, step down LED driver that is easily configured for various applications with an input range from 6V to 40V . The converter employs a high-side current-sense resistor to detect and regulate the LED current. The voltage across the current sense resistor is measured and regulated to within 100mV ±20mV . When VEN>0.3V, the output of the comparator goes high and the other blocks are enabled. A high-side resistor, RSENSE, senses the output current. When the switch is on, R2 is shorted and R1 sets the output current upper- threshold. When the switch is off, R1 and R2 set the output current lower-threshold, and the ratio of R1 and R2 determines the current hysteresis. Enable Control Once Input voltage is applied, th e internal reference is connecte d to EN/DIM pin through pull up resistor. If the EN/DIM pin is left open, the IC automatically starts up to the maximum brightness. Adding a capacitor to this pin can hereby program a soft-start time. Applying an external voltage range from 0.3V to 2.5V to the EN/DIM pin linearly controls the current-sense voltage reference from 0mV to 100mV for analog dimming. Applying an external PWM voltage with an amplitude of 2.5V to the EN/DIM pin achieves PWM dimming. For
http://www.bookly.com/ 40V 1.2A Step-Down Dimmable LED Driver additional information on the flexibl e external PWM dimmin g method, please refer to the “Selecting Dimming Control Mode” section. System Soft Start The voltage on the EN/DIM pin is the induct or current reference. An external capacitor from the EN/DIM pin to ground provides a soft-start delay. Dimming Control BM4115 provides two dimming methods: PWM dimming and DC analog dimming. To use PWM dimming, apply a square wave to the EN/DIM pin. To use analog dimming, apply a 0.3V-to-2.5V DC voltage to this pin.
Application Information
The LED current is set by the current-setting resistor between the IN and RS pins, where: 𝑅𝑆𝐸𝑇 = 100𝑚𝑉 𝐼𝐿𝐸𝐷 For RSET=0.2Ω, the LED current is set to 500mA Selecting the Inductor Lower value of the inductor results in higher switching frequencies, leading to larger switch loss. For most applications, select a switching frequency between 200kHz and 600kHz. Estimate the inductor value based on the desired switching frequency, where: 𝐿 = 𝑉𝑂𝑈𝑇 ×(1− 𝑉𝑂𝑈𝑇 𝑉𝐼𝑁 0.4×𝐼 𝐿𝐸𝐷 ×𝑓𝑆𝑊 For higher efficiency, use inductors with low DC resistance. Selecting the Diode The output diode supplies current flowing path to the inductor when the internal MOSFET is off. To reduce losses due to the diode forward voltage and recovery time, use a Schottky diode. Select a diode rated with a reverse voltage greater than the input voltage. The average current rating must exceed the maximum expected load current, and the peak current rating must exceed the peak inductor current. Selecting Soft-Start Capacitor The delay time with the soft -start capacitor can be estimated by 0.2ms/nF. In PWM dimming, select a C<2.2nF to eliminate its effect on the average LED current. Selecting Dimming Control Mode
http://www.bookly.com/ 40V 1.2A Step-Down Dimmable LED Driver The average LED current is proportional to duty cycle of PWM signal. For good PWM dimming linearity, inductor current has to achieve the peak threshold during PWM on time. The minimum PWM duty cycle can be estimated as below： 𝐷𝑀𝐼𝑁 𝑓𝑃𝑊𝑀 = 𝑡1+𝑡2+4× 𝐷 ×𝑇𝑆𝑊 Circuit Layout Consideration Pay careful attention to the PCB board layout and components placement. R SENSE should be placed close to the IN pin and RS pin to minimize set current error. The input loop including the input capacitor, Schottky diode, and internal MOSFET should be as short as possible.
http://www.bookly.com/ 40V 1.2A Step-Down Dimmable LED Driver Package Description TOP VIEW FRONT VIEW SIDE VIEW NOTE: 1. CONTROL DIMENSION IS IN INCHES. DIMENSION IN BRACKET IS IN MILLIMETERS. 2. PACKAGE LENGTH DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. 3. PACKAGE WIDTH DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. 4. LEAD 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. SOT89-5 D R 0.15 C 0.25 E AAB b a e B E1 L1 C BOTTOM VIEW MIN NOM MAX A2 1.40 1.50 1.60 b 0.38 - 0.46 a 0.46 - 0.56 D 4.40 4.50 4.60 E 4.00 4.20 4.40 E1 2.40 2.50 2.60 e L1 0.80 1.00 1.20 SYMBOL MILLIMETER 1.50BSC Size(mm) L/F Size(mil) D1 D2 E2 85×70 1.70REF 1.75REF 2.84REF