Power Management

BD81A76EFV-M

Rohm

6ch White LED Driver Built-in Current Driver Buck-Boost and Boost DC/DC Converter for Automotive 25.Nov.2021 Rev.004

Manufacturer: Rohm

Document: 43 Pages / 2Mb

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Document overview

Manufacturer or author: ROHM CO., LTD.
PDF pages: 43

Technical content

Features

◼ AEC-Q100 Qualified*1 ◼ 6ch Current Driver for LED Drive ◼ Buck-Boost Current Mode DC/DC Converter ◼ Control DC/DC Converter Oscillation Frequency by External Synchronized Signal ◼ Spread Spectrum Function ◼ LSI Protection Function (UVLO, OVP, TSD, OCP, SCP) ◼ LED Abnormality Detection Function (Open/Short) ◼ VOUT Discharge Function (Buck-Boost Structure Limitation) *1 Grade 1

Applications

◼ Automotive CID (Center Information Display) Panel ◼ Car Navigation ◼ Cluster Panel ◼ HUD (Head Up Display) ◼ Small and Medium Type LCD Panels for Automotive Use Key Specifications ◼ Operating Input Voltage Range 4.5 V to 35 V ◼ Output LED Current Accuracy ±3.0 %@50 mA ◼ DC/DC Oscillation Frequency 200 kHz to 2200 kHz ◼ Operating Temperature -40 °C to +125 °C ◼ LED Maximum Output Current 120 mA/ch ◼ LED Maximum Dimming Ratio 10,000:1@100 Hz ◼ PWM Minimum Pulse Width 1.0 µs Package W (Typ) x D (Typ) x H (Max) HTSSOP-B30 10.0 mm x 7.6 mm x 1.0 mm HTSSOP-B30 BD81A76EFV-M Typical Application Circuit Datasheet

1 VCC Input power supply pin

2 SS “Soft Start” capacitor connection

3 COMP Error Amp output

4 RT Oscillation frequency setting resistor connect

5 SYNC External synchronization input pin

6 SSCG Spread spectrum setting capacitor pin

7 GND Small signal GND pin

8 PWM PWM light modulation signal input pin

9 FAIL1 “Failure” signal output pin 1

10 FAIL2 “Failure” signal output pin 2

11 LEDEN1 Enable pin 1 for LED output

12 LEDEN2 Enable pin 2 for LED output

13 LED1 LED output pin 1

14 LED2 LED output pin 2

15 LED3 LED output pin 3

16 LED4 LED output pin 4

17 LED5 LED output pin 5

18 LED6 LED output pin 6

19 OVP Over voltage detection pin

20 ISET LED output current setting pin

21 PGND LED output GND pin

22 OUTL Low side FET gate pin

23 DGND DC/DC converter output GND pin

24 VDISC Output voltage discharge pin

25 SW High side FET source pin

26 OUTH High side FET gate pin

27 BOOT High side FET driver power supply pin

28 VREG Internal constant voltage

29 EN Enable pin

30 CS DC/DC converter input current sense pin

EXP-PAD Back side thermal PAD (Connect to GND)

© 2019 ROHM Co., Ltd. All rights reserved. If there is no description, the mentioned values are typical value. it might occur unstable operation e.g. oscillation. Table 1. LED Control Logic channel, which is not used, with the LEDEN1 and LEDEN2 pins. The truth table for these pins is shown above. and LEDEN2 pins are not switchable during these in operation. Figure 1. ILED vs RISET detects ISET-GND short condition and LED current is turned off.

Buck-Boost DC/DC Converter

voltage is 2.0 V or more, Over Voltage Protection (OVP) is active and stop the DC/DC converter switching. variation. When the OVP pin voltage drops less than 1.94 V after OVP operation, the OVP is released. 𝑅𝑂𝑉𝑃1 is the GND side OVP resistance. 𝑅𝑂𝑉𝑃2 is the Output voltage side OVP resistance. For example, OVP is active when VOUT ≥ 32 V if ROVP1 = 22 kΩ and ROVP2 = 330 kΩ. Figure 4. fOSC vs RRT resistance of RRT using the above data and the equation below. Take note that operation could not be guaranteed in the case of settings other than the recommended range.

Buck-Boost DC/DC Converter - continued

Operation in Spread Spectrum Clock Generation (SSCG) is possible by connecting capacitor to the SSCG pin. becomes 100 % to 80 % of switching frequency when SSCG is not used. Figure 5. SSCG Noise Reduction Image Figure 6. SSCG System Diagram fSSCG can be calculated by the following equation. Set it to satisfy the equation of 0.4 kHz ≤ fSSCG ≤ 30 kHz. Furthermore, quantity of noise reduction S [dB] in SSCG can be roughly estimated by the equation below. Short the SSCG pin and the GND pin when SSCG function is not used. frequency set by the RT pin resistance. for the calculation of SS time.

25.Nov.2021 Rev.004 © 2019 ROHM Co., Ltd. All rights reserved. www.rohm.com TSZ22111 • 15 • 001 3. Buck-Boost DC/DC Converter - continued (7) Maximum Duty When DC/DC switching reaches Maximum Duty, expected VOUT voltage could be not output, and LED lights- out might occur by the reduction of LED output current and detection of ground short protection. Set input condition and load condition such that it does not reach Maximum Duty. (8) DC/DC Switching Control at Over Voltage Output (LSDET) When the lowest voltage in LED1 to LED 6 pins (DC/DC feedback voltage) is more than 1.24 V, LSDET function works and turns off the switching of the DC/DC converter and maintains the COMP voltage (switching Duty). This function reduces the VOUT voltage quickly and intended to output stable switching Duty when VOUT is higher than the aim voltage. For example, LSDET works at the time of the LED6 OPEN detection. The timing chart example is described below. (9) PWM Pulse and DC/DC Switching After the fall of the PWM pulse, DC/DC switching is output 12 times and after that, turn off the DC/DC switching during PWM = Low. When PWM becomes High again, the DC/DC switching is on. Because of this, when PWM pulse width is short, it can maintain the output voltage and output the stable LED current. PWM OUTL VOUT ILED Stable LED current output VOUT keep +12 pulses

0.3 V or less

4.5 V and more

starting up of EN or release of UVLO. Also, those output is unstable when EN = Low and detecting UVLO. If the FAIL pin is used as a flag output, it is recommended to pull-up the FAIL1, FAIL2 pins to the VREG pin. The recommended value of pull-up resistance is 100 kΩ.

25.Nov.2021 Rev.004 © 2019 ROHM Co., Ltd. All rights reserved. www.rohm.com TSZ22111 • 15 • 001 4. Protection Feature - continued (1) Under-Voltage Lock Out (UVLO) The UVLO shuts down DC/DC converter and Current Driver when VCC ≤ 3.5 V or VVREG ≤ 2.0 V. And UVLO is released by VCC ≥ 4.0 V and VVREG ≥ 3.5 V. (2) Thermal Shutdown (TSD) The TSD shuts down DC/DC converter and Current Driver when the Tj 175 °C or more, and releases when the Tj becomes 150 °C or less. (3) Over Voltage Protection (OVP) The output voltage of DC/DC converter is detected from the OVP pin voltage, and the over voltage protection is activate if the OVP pin voltage becomes ≥ 2.0 V. When OVP is activated, the switching operation of the DC/DC converter turns off. And the OVP pin voltage becomes ≤ 1.94 V, OVP is released and the switching operation of the DC/DC converter turns on. (4) Over Current Protection (OCP) The OCP detects the coil current by monitoring the voltage of the high side resistor, and activates when VCS ≤ VCC-0.2 V. When the OCP is activated, the switching operation of the DC/DC converter turns off. And VCS > VCC-0.2 V, OCP is released and the switching operation of the DC/DC converter turns on. (5) Short Circuit Protection (SCP) The SCP can be operated when the SS pin voltage reaches 3.3 V while start-up. When any of the LED1 to LED6 pins voltage becomes 0.3 V or less or V OVP ≤ 0.57 V, the built-in counter operation starts. The clock frequency of counter is the oscillation frequency (f OSC), which is determined by RRT. After it counts 32770, the DC/DC converter and the current driver are latched off. When fosc = 300 kHz, the co unt time is 100 ms and SCP operates after this count time. If all of the LED pin voltage becomes more than 0.3 V or V OVP ≥ 1.0 V before 32770 count, the counter resets and SCP is not detected. (6) LED Open Protection When any of the LED pins voltage is 0.3 V or less and VOVP 2.0 V or more, LED open is detected and latches off the open LED channel only. (7) LED Short Protection If any of VLED1 to VLED6 is 4.5 V or more, the built-in counter operation starts. The clock frequency of counter is the oscillation frequency (f OSC), which is determined by R RT. After it counts 32770, latches off the short LED channel only. When fosc = 300 kHz, the count time is 100 ms and SCP operates after this count time. During PWM dimming, the LED Short Protection is carried out only when PWM = High. If the condition of LED Short is reset while working the counter, the counter resets and LED Short is not detected. (8) PWM Low Interval Detect The low interval of PWM input is counted by built -in counter during EN = High. The clock frequency of counter is the oscillation frequency (f OSC), which is determined by R RT. It stops the operation of circuits except VREG at 32768 counts. When fOSC = 300 kHz, the count time is 100 ms and the Low interval of PWM is detected after this count time.

Protection Feature - continued

𝑡𝐷𝐼𝑆𝐶 is the DC/DC converter output discharge time. 𝑉𝑂𝑈𝑇 is the DC/DC converter output voltage. 𝐼𝐷𝐼𝑆𝐶 is the discharge current. From the graph below, find the IDISC value in 25 % VOUT voltage, and substitute it in the above equation. in VOUT = 20 V, and calculate the discharge time. Always check with actual machine because the tDISC found here is a reference level. Figure 7. IDISC vs VOUT

25.Nov.2021 Rev.004 © 2019 ROHM Co., Ltd. All rights reserved. www.rohm.com TSZ22111 • 15 • 001 Absolute Maximum Ratings (Ta = 25 °C) Parameter Symbol Rating Unit Power Supply Voltage VCC 40 V BOOT, OUTH Pin Voltage VBOOT, VOUTH 45 V SW, CS Pin Voltage VSW, VCS 40 V BOOT-SW Pin Voltage VBOOT-SW 7 V LED1 to LED6, VDISC Pin Voltage VLEDn (n = 1 to 6), VVDISC 40 V PWM, SYNC, EN Pin Voltage VPWM, VSYNC, VEN -0.3 to +7 V VREG, OVP , FAIL1, FAIL2, SS, RT, SSCG Pin Voltage VVREG, VOVP, VFAIL1, VFAIL2, VSS, VRT, VSSCG -0.3 to +7 < VCC V LEDEN1, LEDEN2, ISET, COMP, OUTL Pin Voltage VLEDEN1, VLEDEN2, VISET VCOMP, VOUTL -0.3 to +7 < VVREG V Maximum Junction Temperature Tjmax 150 °C Storage Temperature Range Tstg -55 to +150 °C LED Maximum Output Current ILED 120*1 mA Caution 1: Operating the IC over the absolute maximum ratings may damage the IC. The damage can either be a short circuit between pins o r an open circuit between pins and the internal circuitry. Therefore, it is important to consider circuit protection measures, such as adding a fuse, in case the IC is operated over the absolute maximum ratings. Caution 2: Should by any chance the maximum junction temperature rating be exceeded the rise in temperature of the chip may result in deterioration of the properties of the chip. In case of exceeding this absolute max imum rating, design a PCB board with thermal resistance taken into consideration by increasing board size and copper area so as not to exceed the maximum junction temperature rating. *1 Current level per channel. Set the LED current that does not over Junction Temperature Range (Tj) maximum.

25.Nov.2021 Rev.004 © 2019 ROHM Co., Ltd. All rights reserved. www.rohm.com TSZ22111 • 15 • 001 Recommended Operating Conditions Parameter Symbol Min Typ Max Unit Power Supply Voltage*1 VCC 4.5 12 35 V Operating Temperature Topr -40 +25 +125 °C DC/DC Oscillation Frequency fOSC 200 300 2200 kHz External Synchronized Frequency *2 *3 fSYNC 200 or higher of fOSC x 0.8 300 2200 or lower of fOSC x 1.2 kHz External Synchronized Pulse Duty DSYNC 40 50 60 % *1 This indicates the voltage near the VCC pin. Be careful of voltage drop by the impedance of power line. *2 When external synchronization frequency is not used, connect the SYNC pin to open or GND. *3 When external synchronization frequency is used, do not change to internal oscillation frequency along the way. Operating Conditions (External Constant Range) Parameter Symbol Min Typ Max Unit VREG Capacity CVREG 1.0 2.2 4.7 μF LED Current Setting Resistance RISET 41 100 250 kΩ Oscillation Frequency Setting Resistance RRT 3.6 27 41 kΩ Soft Start Capacity Setting CSS 0.047 0.1 0.47 μF Spread Spectrum Setting Capacity CSSCG 4.7 10 47 nF

25.Nov.2021 Rev.004 © 2019 ROHM Co., Ltd. All rights reserved. www.rohm.com TSZ22111 • 15 • 001 Electrical Characteristics(Unless otherwise specified, VCC = 12 V, Ta = -40 °C to +125 °C) Parameter Symbol Min Typ Max Unit Conditions Circuit Current ICC - - 10 mA EN = High, SYNC = High, RT = OPEN, PWM = Low, ISET = OPEN, CIN = 10 μF Standby Current IST - - 10 μA EN = Low, VDISC = OPEN [VREG] Reference Voltage VVREG 4.5 5.0 5.5 V IVREG = -5 mA, CVREG = 2.2 μF [OUTH] OUTH High Side ON-Resistor RONHH 1.5 3.5 7.0 Ω IOUTH = -10 mA OUTH Low Side ON-Resistor RONHL 0.8 2.5 5.5 Ω IOUTH = 10 mA OCP Detection Voltage VOLIMIT VCC-0.22 VCC-0.20 VCC-0.18 V OCP Detection Mask Time tOLIMIT - 30 - ns VCS = VCC-0.5V [OUTL] OUTL High Side ON-Resistor RONLH 1.5 3.5 10.0 Ω IOUTL = -10 mA OUTL Low Side ON-Resistor RONLL 0.8 2.5 5.5 Ω IOUTL = 10 mA [SW] SW ON-Resistor RON_SW 4.0 10.0 25.0 Ω ISW = 10 mA [ERRAMP] LED Control Voltage VLED 0.9 1.0 1.1 V COMP Sink Current ICOMPSINK 35 80 145 μA VLEDn = 2 V (n = 1 to 6), VCOMP = 1 V COMP Source Current ICOMPSOUCE -145 -80 -35 μA VLEDn = 0.5 V (n = 1 to 6), VCOMP = 1 V [Oscillator] Oscillation Frequency 1 fOSC1 285 300 315 kHz RRT = 27 kΩ Oscillation Frequency 2 fOSC2 1800 2000 2200 kHz RRT = 3.6 kΩ [OVP] OVP Detection Voltage VOVP1 1.9 2.0 2.1 V VOVP: Sweep up OVP Hysteresis Width VOVPHYS1 0.02 0.06 0.10 V VOVP: Sweep down

25.Nov.2021 Rev.004 © 2019 ROHM Co., Ltd. All rights reserved. www.rohm.com TSZ22111 • 15 • 001 Electrical Characteristics - continued(Unless otherwise specified, VCC = 12 V, Ta = -40 °C to +125 °C) Parameter Symbol Min Typ Max Unit Conditions [UVLO] UVLO Detection Voltage VUVLO 3.2 3.5 3.8 V VCC: Sweep down UVLO Hysteresis Width VUHYS 0.25 0.50 0.75 V VCC: Sweep up, VVREG > 3.5 V [LED Output] LED Current Relative Dispersion ILED1 -3 - +3 % ILED = 50 mA, Ta = 25 °C ΔILED1 = (ILEDn/ILEDn_AVG-1)x 100 (n = 1 to 6) -5 - +5 % ILED = 50 mA, Ta = -40 °C to +125 °C ΔILED1 = (ILEDn/ILEDn_AVG-1)x 100 (n = 1 to 6) LED Current Absolute Dispersion ILED2 -3 - +3 % ILED = 50 mA, Ta = 25 °C ΔILED2 = (ILEDn/50mA-1) x 100 (n = 1 to 6) -5 - +5 % ILED = 50 mA, Ta = -40 °C to +125 °C ΔILED2 = (ILEDn/50mA-1) x 100 (n = 1 to 6) ISET Voltage VISET 0.9 1.0 1.1 V RISET = 100 kΩ PWM Minimum Pulse Width tMIN 1 - - μs fPWM = 100 Hz to 20 kHz, ILED = 20 mA to 100 mA PWM Frequency fPWM 0.1 - 20 kHz [Protection Circuit] LED Open Detection Voltage VOPEN 0.2 0.3 0.4 V VLEDn :(n = 1 to 6) Sweep down LED Short Detection Voltage VSHORT 4.2 4.5 4.8 V VLEDn :(n = 1 to 6) Sweep up LED Short Detection Latch OFF Delay Time tSHORT 70 100 130 ms RRT = 27 kΩ SCP Latch OFF Delay Time tSCP 70 100 130 ms RRT = 27 kΩ PWM Latch OFF Delay Time tPWM 70 100 130 ms RRT = 27 kΩ ISET-GND Short Protection Impedance ISETPROT - - 4.7 kΩ LSDET Detection Voltage VLSDET - 1.24 - V [Logic Input Voltage] Input High Voltage VINH 2.1 - VVREG V EN, SYNC, PWM, LEDEN1, LEDEN2 Input Low Voltage VINL GND - 0.8 V EN, SYNC, PWM, LEDEN1, LEDEN2 Input Current IIN 15 50 100 μA VIN = 5 V (EN, SYNC, PWM, LEDEN1, LEDEN2) [FAIL Output (Open Drain)] FAIL Low Voltage VOL - 0.1 0.2 V IFAIL = 0.1 mA

4 LED loads per channel, all channels have loads)

Figure 15. Efficiency vs LED Current(n = 1 to 6)

8 LED loads per channel, all channels have loads)

25.Nov.2021 Rev.004 © 2019 ROHM Co., Ltd. All rights reserved. www.rohm.com TSZ22111 • 15 • 001 Timing Chart (Start-up and Protection) *1 EN is input after input VCC in the timing chart above, but there is no problem to input EN, PWM, and SYNC before input VCC. EN i s judged as *2 The count time of 32770 clk x 1/fOSC. In case of fosc=300 kHz, the count time is 100 ms(typ). *3 The above timing chart is when the FAIL1 and FAIL2 pins are pulled up to the VREG pin. ① When VOVP is less than 1.0 V, regardless of PWM input, the DC/DC switching operation is active (Pre -Boost function). And if VOVP reaches 1.0 V, the Pre-Boost is finished. Only when PWM is activated, switches to the Normal mode which operates the DC/DC switching. ② When VLED2 is 0.3 V or less and V OVP is 2.0 V or more, LED Open Protect is active and LED2 is turned OFF . Then FAIL2 becomes Low. ③ If the condition of VLED3 is 4.5 V or more and passes 100 ms (@f OSC = 300 kHz), LED3 is turned OFF . Then FAIL2 becomes Low. ④ When VLED4 is shorted to GND, increase the VOUT voltage. Then V OVP rises 2.0 V or more and detect OVP . FAIL1 becomes Low. If OVP occurs, DC/DC switching is OFF and decrease the VOUT voltage, then OVP repeats ON/OFF . And DC/DC switching and LED current of eac h channel is turned OFF after 100 ms by detecting ground short protection. (In case of fOSC = 300 kHz).

25.Nov.2021 Rev.004 © 2019 ROHM Co., Ltd. All rights reserved. www.rohm.com TSZ22111 • 15 • 001 Timing Chart (Start-up and EN Restart) *1 The Low section during EN restart requires 2.0 ms or more. Restart after VOUT voltage is discharged. VOUT discharge function or external discharge switch is recommended. If EN is restarted with remaining VOUT voltage, LED flickering might occur.

25.Nov.2021 Rev.004 © 2019 ROHM Co., Ltd. All rights reserved. www.rohm.com TSZ22111 • 15 • 001 PCB Board External Components List (Buck-Boost Application) * The above components are modified according to operating conditions and load to be used.

25.Nov.2021 Rev.004 © 2019 ROHM Co., Ltd. All rights reserved. www.rohm.com TSZ22111 • 15 • 001 Selection of Components Externally Connected - continued 1. Derivation of Maximum Input Leak Current IL_MAX Output Application Circuit Diagram (Buck-Boost Application) (1) Maximum Output Voltage (VOUT_MAX) Computation Consider the Vf variation and number of LED connection in series for VOUT_MAX derivation 𝑉𝑂𝑈𝑇_𝑀𝐴𝑋 = (𝑉𝑓 + ∆𝑉𝑓) × 𝑁 + 1.1 where: 𝑉𝑂𝑈𝑇_𝑀𝐴𝑋 is the maximum output voltage. 𝑉𝑓 is the LED Vf voltage. ∆𝑉𝑓 is the LED Vf voltage variation. 𝑁 is the LED series number. (2) Maximum Output Current IOUT_MAX Computation 𝐼𝑂𝑈𝑇_𝑀𝐴𝑋 = 𝐼𝐿𝐸𝐷 × 1.05 × 𝑀 where: 𝐼𝑂𝑈𝑇_𝑀𝐴𝑋 is the maximum output current. 𝐼𝐿𝐸𝐷 is the output current per channel. 𝑀 is the LED parallel number. Internal IC CS OUTH SW COUT OUTL VIN RCS D2L VOUT IL

25.Nov.2021 Rev.004 © 2019 ROHM Co., Ltd. All rights reserved. www.rohm.com TSZ22111 • 15 • 001 1. Derivation of Maximum Input Leak Current IL_MAX - continued (3) Maximum Input Peak Current IL_MAX Computation 𝐼𝐿_𝑀𝐴𝑋 = 𝐼𝐿_𝐴𝑉𝐺 + 1 2 ∆𝐼𝐿 where: 𝐼𝐿_𝑀𝐴𝑋 is the maximum input current. 𝐼𝐿_𝐴𝑉𝐺 is the maximum input average current. ∆𝐼𝐿 is the coil current amplification. (In case of Boost Application) 𝐼𝐿_𝐴𝑉𝐺 = 𝑉𝑂𝑈𝑇_𝑀𝐴𝑋 × 𝐼𝑂𝑈𝑇_𝑀𝐴𝑋 𝜂 × 𝑉𝐶𝐶 ∆𝐼𝐿 = 𝑉𝐶𝐶 𝐿 × 1 𝑓𝑂𝑆𝐶 × 𝑉𝑂𝑈𝑇_𝑀𝐴𝑋 − 𝑉𝐶𝐶 𝑉𝑂𝑈𝑇_𝑀𝐴𝑋 (In case of Buck-Boost application) 𝐼𝐿_𝐴𝑉𝐺 = (𝑉𝐶𝐶 + 𝑉𝑂𝑈𝑇_𝑀𝐴𝑋) × 𝐼𝑂𝑈𝑇_𝑀𝐴𝑋 𝜂 × 𝑉𝐶𝐶 ∆𝐼𝐿 = 𝑉𝐶𝐶 𝐿 × 1 𝑓𝑂𝑆𝐶 × 𝑉𝑂𝑈𝑇_𝑀𝐴𝑋 𝑉𝐶𝐶 + 𝑉𝑂𝑈𝑇_𝑀𝐴𝑋 (In case of Buck application) 𝐼𝐿_𝐴𝑉𝐺 = 𝐼𝑂𝑈𝑇_𝑀𝐴𝑋 ∕ 𝜂 ∆𝐼𝐿 = 𝑉𝑂𝑈𝑇 𝐿 × 1 𝑓𝑂𝑆𝐶 × 𝑉𝐶𝐶 − 𝑉𝑂𝑈𝑇_𝑀𝐴𝑋 𝑉𝐶𝐶 where: 𝑉𝐶𝐶 is the supply voltage. 𝜂 is the efficiency. 𝑓𝑂𝑆𝐶 is the DC/DC oscillation frequency. 𝐿 is the coil value.

The worst case for VCC is minimum, so the minimum value should be applied in the equation.
BD81A76EFV-M adopts the current mode DC/DC converter control and is appropriately designed for coil value. The abovementioned value is recommended according to efficiency and stability. If choose the L values outside this recommended range, it not to be guaranteed the stable continuous operation. For example, it may cause irregular switching waveform.
η (efficiency) is around 80 %.

25.Nov.2021 Rev.004 © 2019 ROHM Co., Ltd. All rights reserved. www.rohm.com TSZ22111 • 15 • 001 Selection of Components Externally Connected - continued 2. Setting of Over Current Protection Value (IOCP) 𝐼𝑂𝐶𝑃 = 𝑉𝑂𝐶𝑃_𝑀𝐼𝑁 𝑅𝐶𝑆 > 𝐼𝐿_𝑀𝐴𝑋 [A] where: 𝐼𝑂𝐶𝑃_𝑀𝐼𝑁 is the overcurrent protection detect voltage. 𝑉𝑂𝐶𝑃_𝑀𝐼𝑁 is the overcurrent protection detect voltage (0.18 V). 𝑅𝐶𝑆 is the current detect resistance. 𝐼𝐿_𝑀𝐴𝑋 is the maximum input peak current. RCS should be selected by the above equation. 3. Selection of Inductor In order to achieve stable operation of the current mode DC/DC converter, it is recommended adjusting the L value within the range indicated below. 0.05 < 𝑉𝑂𝑈𝑇×𝑅𝐶𝑆 𝐿×106 < 0.63×𝑓𝑂𝑆𝐶 106 [V/μs] where: 𝑉𝑂𝑈𝑇 is the DC/DC converter output voltage. 𝑅𝐶𝑆 is the current detect resistance. 𝐿 is the coil value. 𝑓𝑂𝑆𝐶 is the DC/DC oscillation frequency. Consider the deviation of L value and set with enough margins. It is more stable by reducing the value of 𝑉𝑂𝑈𝑇×𝑅𝐶𝑆 𝐿×106 , however it slows down the response time. Also, the following equation should be satisfied during coil selection in case it is used in VCC = 5 V or less. 𝐿 < 12 × 𝑉𝐶𝐶 × 𝑉𝐶𝐶 × 𝜂 𝑉𝑂𝑈𝑇 × 𝐼𝐿𝐸𝐷 × 𝑀 × 𝑓𝑂𝑆𝐶 where: 𝐿 is the coil value. 𝑉𝐶𝐶 is the supply voltage. 𝜂 is the efficiency. 𝑉𝑂𝑈𝑇 is the DC/DC converter output voltage. 𝐼𝐿𝐸𝐷 is the LED current per channel. 𝑓𝑂𝑆𝐶 is the DC/DC oscillation frequency. 𝑀 is the LED parallel number. LED intensity may drop when a coil which does not satisfy the above is chosen.

25.Nov.2021 Rev.004 © 2019 ROHM Co., Ltd. All rights reserved. www.rohm.com TSZ22111 • 15 • 001 Selection of Components Externally Connected - continued 4. Selection of Voltage/Current Ratings of Coil (L), Diode (D1, D2), FET (M1, M2), RCS, and COUT Current Rating Voltage Rating Heat Loss Coil L > IL_MAX - - Diode D1 > IOCP > VCC_MAX - Diode D2 > IOCP > VOVP_MAX - FET M1 > IOCP > VCC_MAX - FET M2 > IOCP > VOVP_MAX - RCS - - > IOCP 2 x RCS COUT - > VOVP_MAX - Consider deviation of external parts and set with enough margins. In order to achieve fast switching, choose the FET’s with smaller gate-capacitance. 5. Setting of Output Capacitor Select the output capacitor COUT based on the requirements of the ripple voltage VOUTpp. 𝑉𝑂𝑈𝑇𝑝𝑝 = 20×𝐼𝐿𝐸𝐷×𝑀 𝑓𝑂𝑆𝐶×𝐶𝑉𝑂𝑈𝑇×𝜂 + ∆𝐼𝐿 × 𝑅𝐸𝑆𝑅 [V] where: 𝑉𝑂𝑈𝑇𝑝𝑝 is the VOUT ripple voltage. 𝐼𝐿𝐸𝐷 is the LED current per channel. 𝑀 is the LED parallel number. 𝑓𝑂𝑆𝐶 is the DC/DC oscillation frequency. 𝐶𝑉𝑂𝑈𝑇 is the VOUT capacity. 𝜂 is the efficiency. ∆𝐼𝐿 is the coil current amplification. 𝑅𝐸𝑆𝑅 is the equivalent series resistance of output capacitor COUT. The actual VOUT ripple voltage is affected by PCB layout and external components characteristics. Therefore, check with the actual machine, and design a capacity with enough margins to fit in allowable ripple voltage. The maximum value of COUT that can be set is 500 µF . 6. Selection of Input Capacitor An input capacitor which is 10 μF or more with low ESR ceramic capacitor is recommended. An input capacitor which is not recommended may cause large ripple voltage at the input and hence lead to malfunction of the IC. 7. Selection of BOOT - SW Capacitor When using the Buck-Boost application or Buck application, insert 0.1 μF capacitor between the BOOT pin and the SW pin.

25.Nov.2021 Rev.004 © 2019 ROHM Co., Ltd. All rights reserved. www.rohm.com TSZ22111 • 15 • 001 Selection of Components Externally Connected - continued 8. Setting of Phase Compensation Circuit COMP Pin Application Schematic(n = 1 to 6) Stability Condition of Application The stability in LED voltage feedback system is achieved when the following conditions are met. (1) When gain is 1 (0 dB), the phase delay is 150° or less (or simply, phase margin is 30° or more). (2) When gain is 1 (0 dB), the frequency (Unity Gain Frequency) is 1/10 or less of switching frequency. To assure stability based on phase margin adjustment is setting the Phase-lead fz close to unity gain frequency. In addition, the Phase-lag fp1 is decided based on COUT and output impedance RL. The respective formulas are as follows. Phase-lead 𝑓𝑧 = 1/(2𝜋𝑅𝑃𝐶𝐶𝑃𝐶) [Hz] Phase-lag 𝑓𝑝1 = 1/(2𝜋𝑅𝐿𝐶𝑂𝑈𝑇) [Hz] * The output impedance that is calculated in 𝑅𝐿 = 𝑉𝑂𝑈𝑇/𝐼𝑂𝑈𝑇 To make a good result, set fz between 1 kHz to 10 kHz. Substitute the value in the maximum load for RL. Further, this setting is easily obtained, and the adjustment with the actual machine may be necessary because it is not strictly calculated. In case of mass production design, thorough confirmation with the actual machine is necessary because these characteristics can change based on board layout, load condition and etc.

25.Nov.2021 Rev.004 © 2019 ROHM Co., Ltd. All rights reserved. www.rohm.com TSZ22111 • 15 • 001 Selection of Components Externally Connected - continued 9. Setting of Over Voltage Protection (OVP) Over voltage protection (OVP) is set from the external resistance ROVP1, ROVP2. The setting described below is important in the either boost, buck and buck-boost applications. The OVP pin detects the over voltage when it is 2.0 V (Typ) or more and stops the DC/DC switching. In addition, it detects the open condition when the OVP pin is at 2.0 V (Typ) or more and the LED1 to LED6 pins voltage is at 0.3 V (Typ) or less, and the circuit is latched to OFF (Refer to Protection Feature). In preventing error in detection of OPEN, it is necessary that the resistor divide voltage of the maximum value of output voltage shall be less than the minimum value of OPEN detection voltage. Set the ROVP1, ROVP2 in such a way the formula shown below can be met. 𝑉𝑂𝑈𝑇(𝑀𝑎𝑥) × 𝑅𝑂𝑉𝑃1 where: 𝑉𝑂𝑈𝑇 is the DC/DC output voltage. 𝑉𝑂𝑉𝑃𝑜𝑝𝑒𝑛 is the OVP pin open detection voltage. Example 1: When Vf = 3.2 V±0.3 V LED is used in 8 series 𝑉𝑂𝑈𝑇(𝑀𝑎𝑥) = 1.1(𝐿𝐸𝐷 𝑐𝑜𝑛𝑡𝑟𝑜𝑙 𝑣𝑜𝑙𝑡𝑎𝑔𝑒 𝑀𝑎𝑥) + (3.2 + 0.3) × 8 = 29.1 [V] Open Detection OVP Pin Voltage 𝑉𝑂𝑉𝑃𝑜𝑝𝑒𝑛(𝑀𝑖𝑛) = 1.9 [V] If ROVP1 = 20 kΩ, set by ROVP2 > 286.3 kΩ from (1). Example 2: When Vf = 3.2 V±0.3 V LED is used in 3series 𝑉𝑂𝑈𝑇(𝑀𝑎𝑥) = 1.1(𝐿𝐸𝐷 𝑐𝑜𝑛𝑡𝑟𝑜𝑙 𝑣𝑜𝑙𝑡𝑎𝑔𝑒 𝑀𝑎𝑥) + (3.2 + 0.3) × 3 = 11.6 [V] Open Detection OVP Pin Voltage 𝑉𝑂𝑉𝑃𝑜𝑝𝑒𝑛(𝑀𝑖𝑛) = 1.9 [V] If ROVP1 = 20 kΩ, set by ROVP2 > 102.1 kΩ from (1). ROVP1 OVP VOUT Internal IC 2.0 V / 1.94 V 1.0 V / 0.57 V ROVP2

25.Nov.2021 Rev.004 © 2019 ROHM Co., Ltd. All rights reserved. www.rohm.com TSZ22111 • 15 • 001 Selection of Components Externally Connected - continued 12. Confirmation of Actual Operation Set up the external components value by procedures and attentions mentioned above. However, those settings above are not guaranteed because these are theoretically calculated and it does not include the external parts' variation or characteristics changing. The overall characteristics may change depend on power supply voltage, LED current, LED number, inductance, output capacitance, switching frequency, and PCB layout. We strongly recommend verifying your design by taking the actual measurements. Additional parts for EMC The example of EMC countermeasure components is shown in the chart below. 1. The resistance for adjusting Slew Rate of high side FET 2. The capacitor for reducing current loop noise of high side FET. 3. The capacitor for reducing noise of high frequency on power line. 4. The low pass filter for reducing noise of power line. 5. The common mode filter for reducing noise of power line. 6. The snubber circuit for reducing noise of high frequency of low side FET. 7. The snubber circuit for reducing ringing of low side FET switching. Application Circuit Reference Example (Including EMC Countermeasure Components) It is basically non-recommended to connect a capacitor to the LED1 to LED6 pins. Please refer PCB Application Circuit. When the connection of the capacitor is necessary for noise measures, please refer to us.

25.Nov.2021 Rev.004 © 2019 ROHM Co., Ltd. All rights reserved. www.rohm.com TSZ22111 • 15 • 001 Operational Notes 1. Reverse Connection of Power Supply Connecting the power supply in reverse polarity can damage the IC. Take precautions against reverse polarity when connecting the power supply, such as mounting an external diode between the power supply and the IC’s power supply pins. 2. Power Supply Lines Design the PCB layout pattern to provide low impedance supply lines. Furthermore, connect a capacitor to ground at all power supply pins. Consider the effect of temperature and aging on the capacitance value when using electrolytic capacitors. 3. Ground Voltage Except for pins the output and the input of which were designed to go below ground, ensure that no pins are at a voltage below that of the ground pin at any time, even during transient condition. 4. Ground Wiring Pattern When using both small -signal and large -current ground traces, the two ground traces should be routed separately but connected to a single ground at the reference point of the application board to avoid fluctuations in the small -signal ground c aused by large currents. Also ensure that the ground traces of external components do not cause variations on the ground voltage. The ground lines must be as short and thick as possible to reduce line impedance. 5. Recommended Operating Conditions The function and operation of the IC are guaranteed within the range specified by the recommended operating conditions. The characteristic values are guaranteed only under the conditions of each item specified by the electrical characteristics. 6. Inrush Current When power is first supplied to the IC, it is possible that the internal logic may be unstable and inrush current may flow instantaneously due to the internal powering sequence and delays, especially if the IC has more than one power supply. Therefore, give speci al consideration to power coupling capacitance, power wiring, width of ground wiring, and routing of connections. 7. Testing on Application Boards When testing the IC on an application board, connecting a capacitor directly to a low -impedance output pin may subject the IC to stress. Always discharge capacitors completely after each process or step. The IC’s power supply should always be turned off completely before connecting or removing it from the test setup during the inspection process. To prevent damage from static discharge, ground the IC during assembly and use similar precautions during transport and storage. 8. Inter-pin Short and Mounting Errors Ensure that the direction and position are correct when mounting the IC on the PCB. Incorrect mounting may result in damaging the IC. Avoid nearby pins being shorted to each other especially to ground, power supply and output pin. Inter-pin shorts could be due to many reasons such as metal particles, water droplets (in very humid environment) and unintentional sol der bridge deposited in between pins during assembly to name a few.

© 2019 ROHM Co., Ltd. All rights reserved. and extremely low capacitance. If left unconnected, the electric field from the outside can easily charge it. be connected to the power supply or ground line.

Regarding the Input Pin of the IC

When GND > Pin A and GND > Pin B, the P-N junction operates as a parasitic diode. When GND > Pin B, the P-N junction operates as a parasitic transistor. the P substrate) should be avoided. Figure 25. Example of monolithic IC structure temperature and the decrease in nominal capacitance due to DC bias and others.

Thermal Shutdown Circuit (TSD)

25.Nov.2021 Rev.004 © 2019 ROHM Co., Ltd. All rights reserved. www.rohm.com TSZ22111 • 15 • 001 Operational Notes - continued 13. Over Current Protection Circuit (OCP) This IC incorporates an integrated overcurrent protection circuit that is activated when the load is shorted. This protection circuit is effective in preventing damage due to sudden and unexpected incidents. However, the IC should not be used in applications characterized by continuous operation or transitioning of the protection circuit. 14. Disturbance Light In a device where a portion of silicon is exposed to light such as in a WL -CSP and chip products, IC characteristics may be affected due to photoelectric effect. For this reason, it is recommended to come up with countermeasures that will prevent the chip from being exposed to light.

Ordering Information

B D 8 1 A 7 6 E F V - M E 2 Package EFV: HTSSOP-B30 Product Rank M: for Automotive Packaging and forming specification E2: Embossed carrier tape Marking Diagram HTSSOP-B30 (TOP VIEW) Part Number Marking BD81A76EFV LOT Number Pin 1 Mark

25.Nov.2021 Rev.004 © 2019 ROHM Co., Ltd. All rights reserved. www.rohm.com TSZ22111 • 15 • 001 Physical Dimension and Packing Information Package Name HTSSOP-B30 Packing Information Packing Form Embossed carrier tape Quantity 2000 pcs Direction of feed

Revision History

21.Feb.2019 001 New Release 3.Feb.2020 002 Added <Caution of Large LED Current Setting> Change the sentence about "Spread Spectrum Function" (Before) The band of the switching frequency becomes 90 %±10 % of … (After) The band of the switching frequency becomes 100 % to 80 % … Change the calculation of noise reduction S. Added the following sentence to the description of "PCB Application Circuit Diagram" When PWM min pulse width satisfies the following formula, please do not connect a capacitor to LED1 to LED6 pins. It might misdetect LED short protection. When the connection of the capacitor is necessary for noise measures, please refer to us. tMIN ? 10/fOSC tMIN : PWM min pulse width fOSC : DCDC frequency target Added the following sentence to "Selection of Components Externally Connected"/"Confirmation of Actual Operation" It is basically non-recommended to connect a capacitor to the LED1 to LED6 pins. Please refer PCB Application Circuit. When the connection of the capacitor is necessary for noise measures, please refer to us. 12.Feb.2021 003 P .6 Figure 4 X axis name Before：RRT [Ω] After：RRT [kΩ] 25.Nov.2021 004 P.17 Figure 13 Y axis name Before：Efficiency [%] After：LED Current : ILEDn [mA] Figure 13 Title Before：Efficiency vs Temperature After：LED Current vs Temperature

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Notice-PAA-E Rev.004 © 2015 ROHM Co., Ltd. All rights reserved. Precautions Regarding Application Examples and External Circuits 1. If change is made to the constant of an external circuit, please allow a sufficient margin considering variations of the characteristics of the Products and external components, including transient characteristics, as well as static characteristics. 2. You agree that application notes, reference designs, and associated data and information contained in this document are presented only as guidance for Products use. Therefore, in case you use such information, you are solely responsible for it and you must exercise your own independent verification and judgment in the use of such information contained in this document. ROHM shall not be in any way responsible or liable for any damages, expenses or losses incurred by you or third parties arising from the use of such information. Precaution for Electrostatic This Product is electrostatic sensitive product, which may be damaged due to electrostatic discharge. Please take proper caution in your manufacturing process and storage so that voltage exceeding the Products maximum rating will not be applied to Products. Please take special care under dry condition (e.g. Grounding of human body / equipment / solder iron, isolation from charged objects, setting of Ionizer, friction prevention and temperature / humidity control). Precaution for Storage / Transportation 1. Product performance and soldered connections may deteriorate if the Products are stored in the places where: [a] the Products are exposed to sea winds or corrosive gases, including Cl 2, H2S, NH3, SO2, and NO2 [b] the temperature or humidity exceeds those recommended by ROHM [c] the Products are exposed to direct sunshine or condensation [d] the Products are exposed to high Electrostatic 2. Even under ROHM recommended storage condition, solderability of products out of recommended storage time period may be degraded. It is strongly recommended to confirm solderability before using Products of which storage time is exceeding the recommended storage time period. 3. Store / transport cartons in the correct direction, which is indicated on a carton with a symbol. Otherwise bent leads may occur due to excessive stress applied when dropping of a carton. 4. Use Products within the specified time after opening a humidity barrier bag. Baking is required before using Products of which storage time is exceeding the recommended storage time period. Precaution for Product Label A two-dimensional barcode printed on ROHM Products label is for ROHM’s internal use only. Precaution for Disposition When disposing Products please dispose them properly using an authorized industry waste company. Pr ecaution for Foreign Exchange and Foreign Trade act Since concerned goods might be fallen under listed items of export control prescribed by Foreign exchange and Foreign trade act, please consult with ROHM in case of export. Precaution Regarding Intellectual Property Rights 1. All information and data including but not limited to application example contained in this document is for reference only. ROHM does not warrant that foregoing information or data will not infringe any intellectual property rights or any other rights of any third party regarding such information or data. 2. ROHM shall not have any obligations where the claims, actions or demands arising from the combination of the Products with other articles such as components, circuits, systems or external equipment (including software). 3. No license, expressly or implied, is granted hereby under any intellectual property rights or other rights of ROHM or any third parties with respect to the Products or the information contained in this document. Provided, however, that ROHM will not assert its intellectual property rights or other rights against you or your customers to the extent necessary to manufacture or sell products containing the Products, subject to the terms and conditions herein. Other Precaution 1. This document may not be reprinted or reproduced, in whole or in part, without prior written consent of ROHM. 2. The Products may not be disassembled, converted, modified, reproduced or otherwise changed without prior written consent of ROHM. 3. In no event shall you use in any way whatsoever the Products and the related technical information contained in the Products or this document for any military purposes, including but not limited to, the development of mass-destruction weapons. 4. The proper names of companies or products described in this document are trademarks or registered trademarks of ROHM, its affiliated companies or third parties.

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Product Information

BD81A76EFV-M specifications and overview.

Summary

6ch White LED Driver Built-in Current Driver Buck-Boost and Boost DC/DC Converter for Automotive 25.Nov.2021 Rev.004

Description

6ch White LED Driver Built-in Current Driver Buck-Boost and Boost DC/DC Converter for Automotive 25.Nov.2021 Rev.004

Source title BD81A76EFV-M Datasheet(PDF) - Rohm

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