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al1794ev1 user guide quad - channel current - ratio - optimized led driver with analog and pwm dimming al1794ev1 rev1 page 1 of 13 ju ly 2015 www.diodes.com general description these four key elements, ac - to - dc power stage, led driver, led emitter module and wireless connectivity block (enabled by embedded mcu and rf), form a typical system configuration for smart connected lighting (scl) bulbs. al1794, a four - channel constant current regulator (ccr) led driver with analog and pwm dimming control, is targeted for tunable white/color scl applications. powered by constant voltage (cv) power source(s) provided by an ac - dc power conversion block, al1794 generates c onstant currents (cc) driving attached led emitter strings. the channel currents are further modulated by analog or digital pwm signals generated by the associated external mcu. key merits ? cost - effectiveness ? dimming performance ? ease of system implementati on key features ? input voltage range: 6.5v dc to 30v dc ? 4 - channel led drivers : independent analog or pwm dimming control for each channel ? reference current: adjustable r set ? low standby power with enable pin ? e - flicker free high pwm frequency dimming: 0.1%@1khz , 0.4%@4khz , 1.0%@10khz ? uvlo, otp, open, and short protection ? operating temperature range: - 40c to +125c ? low system bom cost ? u - dfn4030 - 14 green moulding compound package applications ? 1 - channel dimmable scl bulbs ? 2 - channel tunable white scl bulbs ? 3 - ch annel tunable white scl bulbs ? 4 - channel tunable white+color scl bulbs ? smart connected led tubes, panel lights, troffers, and ceiling lights al1 794 ev 1 specifications parameter value vled1 input voltage 6.5v d c to 24v d c (note 1) , connect to anode of leds s trings vled2 input voltage c onnect to anode of leds strings if a separate voltage for leds stings is required input voltage s for led1, 2, 3, and 4 0.25 v (minimum) 3.3v ldo 150ma (maximum) led_bar connectors (top, male) 6pins, power and led inputs mcu 1 connectors (bottom, male) 10pins, pwm signals input ic pin test points 16 test points (j3 and j4) xyz dimension 1.9 x 2.0 x 0.6 note 1: vin(max) for al1794 is capable of up to 30v, but vin(max) for ap2204k (3.3v @ 150ma for mcu power) limits t he vin(max) of al1794ev1 board to 24v only. if higher than 24v is required for testing, users can drive vin up to 30v as long as 3.3v power output from the ap2204k is not used.
al1794ev1 user guide quad - channel current - ratio - optimized led driver with analog and pwm dimming al1794ev1 rev1 page 2 of 13 ju ly 2015 www.diodes.com al1794 ic pin assignment pin part number d escriptions name u - dfn4030 - 14 en 1 active - high to enable , internally pulled down pwm4 /gnd 2 pwm signal input for channel 4 , internally pulled down for al1 794. gnd for al1791, al1792, and al1793 . pwm3 /gnd 3 pwm signal input for channel 3, internally pu lled down for al1793 and al1794. g nd for al1791 and al1792 . pwm2 /gnd 4 pwm signal input for channel 2, internally pulled down for al1792, al1793, and al1794. gnd for al1791. pwm1 5 pwm signal input for channel 1, internally pulled down (tie d to gnd when this channel is not used). led1 6 channel 1 led cathode led2 /gnd 7 channel 2 led cathode for al1792, al1793, and al1794. gnd for al1791. gnd 8 ground led 3/gnd 9 channel 3 led cathode for al1793 and al1794. gnd for al1791 and al1792. led 4/gnd 10 channe l 4 led cathode for al1794. gnd for al1791, al1792, and al1793. ledpg 11 led power good indication. asserted low to report insufficient headroom. needs an external pull - up resistor. fault b 12 fault report . asserted low to report faulty conditions. needs an external pull - up resistor. ref 13 reference current setting through external resistor ( r set ) vin 14 voltage input exposed pad exposed pad exposed pad. internally connected to gnd. it should be externally connected to gnd and thermal mass for enhan ced thermal impedance. it should not be used as electrical conduction path. e n p w m 4 / g n d p w m 3 / g n d p w m 2 / g n d p w m 1 l e d 1 l e d 2 / g n d v i n r e f f a u l t b l e d p g l e d 4 / g n d l e d 3 / g n d g n d 1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3 1 4
al1794ev1 user guide quad - channel current - ratio - optimized led driver with analog and pwm dimming al1794ev1 rev1 page 3 of 13 ju ly 2015 www.diodes.com evaluation board figure 1 : top view figure 2 : bottom view connector pin definition: 1. power and ground terminals (3 pins) 1) vled1 - al1794 vin, 3.3v ldo input, and emi tter string power input to anode of emitter strings . C upper left corner (top view) 2) vled2 - emitter string power input to anode of emitter strings. 3) gnd - ground 2. led_bar connectors (6 pins) - (left to right pin sequence) 1) led1 (in) - connected to cathode o f emitter str ing #1 - right most pin (top view) 2) led2 (in) - connected to cathode of emitter string #2 3) led3 (in) - connected to cathode of emitter string #3 4) led4 (in) - connected to cathode of emitter string #4 5) vled 1 (out) - emitter string power input to a node of emitter strings . 6) vled 2 (out) - emitter string power input to anode of emitter strings.
al1794ev1 user guide quad - channel current - ratio - optimized led driver with analog and pwm dimming al1794ev1 rev1 page 4 of 13 ju ly 2015 www.diodes.com 3. mcu1 connectors ( 10 pins) - (left to right pin sequence ) 1) gnd - ground - leftmost pin (top view) 2) 3.3v (out) - 3.3v (output for mcu power); generated by ap2204k - 3 .3 ( wide input voltage range, 150ma uldo regulator, http://diodes.com/datasheets/ap2204.pdf ) with vin(max) at 24v. 3) ledpg (out) - led power good signal 4) faultb (out) - faultb, active low, indication of fault occurrence 5) en (in) - enable al1794 to turn on 6) pwm4 (in) - pwm signal for channel #4 7) pwm3 (in) - pwm signal for channel #3 8) pwm2 (in) - pwm signal for channel #2 9) pwm1 (in) - pwm signal for channel #1 10) gnd 4. test points 1) vled1 connected to vled1 2) vled2 connected to vled2 3) gnd_1, gnd_2, gnd_3, gnd_4 connected to gnd 4) en connected to al179x pin#1 5) pwm4 connected to al179x pin#2 6) pwm3 connected to al179x pin#3 7) pwm2 connected to al179x pin#4 8) pwm1 connected to al179x pin#5 9) led1 connected to al179x pin#6 10) led2 connected to al179x pin#7 11) led3 connected to al179x pin#9 12) led4 connected to al179x pin#10 13) ledpg connected to al179x pin#11 14) faultb connected to al179x pin#12
al1794ev1 user guide quad - channel current - ratio - optimized led driver with analog and pwm dimming al1794ev1 rev1 page 5 of 13 ju ly 2015 www.diodes.com board setup procedure the channel current ratio for channel 1, 2, 3 and 4 are fixed at 1:1:0.75:0.25. the default channel current of led1, led2, led3 and led4, are preset at 250ma, 250ma, 187.5ma and 62.5ma, respectively with rset (r601) of 12k. users can change the current setting by replacing rset to obtain desired current value as follows: 1. ensure that the dc source is switched off or disconnected. 2. connect the dc line wires of power supply to vin and gnd terminals on the board. 3. connect the anode wire of external led string to vled1 of the board. 4. connect t he cathode wire of the external led emitter strings to relevant led channels inputs (led1, led2, led3, led4) of the board. 5. make sure the length of both anode/cathode wires connected between al1794ev1 and leds strings is minimized (less than 1 inch) to redu ce wire inductance and improve ringing performance. 6. ensure that the area around the board is clear and safe, and preferably that the board and leds are enclosed in a transparent safety cover. 7. turn on the main dc power switch. 8. send proper pwm signal patte rn and then turn on the en pin (high) to enable the al1794 ic. 9. led strings should light up according to the dimming pattern driven by pwm signals. caution: 1. make sure the maximum dc input voltage is not higher than 30v dc (if 3.3v power output is not used) , or 24v dc (if 3.3v power output is used).
al1794ev1 user guide quad - channel current - ratio - optimized led driver with analog and pwm dimming al1794ev1 rev1 page 6 of 13 ju ly 2015 www.diodes.com 2. if different current is required, please modify the rset (r601) to proper value before start the turn - on procedure. 3. the maximum recommended channel current is at 500ma (for channel 1 and 2) with rset (r601) at 6k . 4. channel pwm dimming patterns are recommended to be spread out to avoid sharp turn - on and turn - off rush currents. 5. though there are various protection mechanism built in al1794, it is good practice to check maximum dimming pattern to avoid thermal shutdow n (when case ambient temperature exceeds 160oc). thermal resistivity ja (junction - to - ambient) of al1794 is 55 oc/watt. al1794 will have to absorb any additional voltage headroom provided by the vled power input to the anodes of emitter strings. theref ore, thermal management of al1794 must follow the following guidelines: ? pdmax (maximum power dissipation) = (160oc junction shutdown temperature - ambient temperature, e.g. 85oc) / 55oc/w = 1.364watts ? pamax (power to be absorbed by al179x) = (vledx * cu rrent through the emitter string * associated pwm dimming duty cycle) ? thermal management guideline pamax < pdmax
al1794ev1 user guide quad - channel current - ratio - optimized led driver with analog and pwm dimming al1794ev1 rev1 page 7 of 13 ju ly 2015 www.diodes.com pwm dimming linearity tests using pwm dimming signals to create desired dimming effects had the advantages of reducing current to desired ra tio without changing either cct (correlated color temperate) of white emitters or causing color shifts of color emitters. to avoid eflicker ("dark stripes on images" when taking photos or videos with smartphones under pwm dimmed lighting situation), users can use higher pwm frequency (e.g. 4khz and above ). the dimming linearity performance at deep dimming (less than 1% light output) is very important as human eyes are very sensitive to low light situations. for example, ? 10% of measured light is 30% of perceived light ? 5% of measured light is 22% of perceived light ? 1% of measured light is 10% of perceived light ? 0.1% of measured light is 3% of perceived light source: iesna lighting handbook, 9th edition, (new york; iesna, 2000), 27 - 4.
al1794ev1 user guide quad - channel current - ratio - optimized led driver with analog and pwm dimming al1794ev1 rev1 page 8 of 13 ju ly 2015 www.diodes.com dimmin g performances: (pwm frequency 4khz, 1khz, and 10khz) 1. 4khz pwm dimming current linearity test for channel 1, 2, 3 and 4 (250ma:250ma:187.5ma:62.5ma) full - range (0 - 100%) 4khz pwm dimming performance figure 3 : 4khz pwm dimming performance deep dimming (0 - 10%) 4khz pwm dimming performance deep dimming performance of pwm signals are critical performance factor as human eyes are more sensitive to brightness change at low light level figure 4 : 4khz pwm dimming performance below 10% dimming
al1794ev1 user guide quad - channel current - ratio - optimized led driver with analog and pwm dimming al1794ev1 rev1 page 9 of 13 ju ly 2015 www.diodes.com 2. 1khz pwm dimm ing current linearity test for channel 1, 2, 3 and 4 (250ma:250ma:187.5ma:62.5ma) full - range (0 - 100%) 10khz pwm dimming performance figure 5 : 1khz pwm dimming performance deep dimming (0 - 10%) 1khz pwm dimming performance using 1khz pwm signal (vs. 4khz) will further improve deep dimming linearity performance. figure 6 : 1khz pwm dimming performance below 10% dimming
al1794ev1 user guide quad - channel current - ratio - optimized led driver with analog and pwm dimming al1794ev1 rev1 page 10 of 13 ju ly 2015 www.diodes.com 3. 10khz pwm dimming current linearity test for channel 2 full - range (0 - 100%) dimming performance figure 7 : 10khz pwm dimming perfo rmance deep dimming (0 - 10%) 1 0 khz pwm dimming performance figure 8 : 10khz pwm dimming performance 0% - 10% dimming
al1794ev1 user guide quad - channel current - ratio - optimized led driver with analog and pwm dimming al1794ev1 rev1 page 11 of 13 ju ly 2015 www.diodes.com evaluation board schematic figure 9 : evaluation board schematic led1 c681 1.0uf/50v 3.3v gnd_1 vled1' u681 ap2204k 1 2 3 4 5 vin gnd en adj/nc vout 3.3v jp_en 1 2 3.3v vled1 c682 4.7uf/10v c602 100uf/50v led3 j4 1 2 3 4 5 6 7 8 vin ref faultb ledpg led4 led3 gnd gnd' r601 / led1 / led2 / led3 /led4 gnd 12k / 250ma/250ma /187ma /62ma pwm2 pwm4 ledpg 10k / 300ma/300ma /225ma /75ma mcu1 3 4 5 6 7 8 9 1 10 2 ledpg faultb en pwm4 pwm3 pwm2 pwm1 gnd1 gnd2 3.3vcc r608 10k faultb 9k / 333ma/333ma /250ma /83ma vled2 r607 10k gnd_3 al179x test fixture rev_2.0 2.0 ap1794 test fixture a4 1 1 tuesday , february 17, 2015 title size document number rev date: sheet of c621 1uf 6k / 500ma/500ma /375ma /125ma j3 1 2 3 4 5 6 7 8 en pwm4 pwm3 pwm2 pwm1 led1 led2 gnd pwm3 led2 r602 10k pwm1 gnd_4 c601 100uf/50v c603 0.1uf u601 al1794 1 3 4 12 14 2 6 7 9 8 13 11 gd 5 10 en pwm3 pwm2 faultb vin pwm4 led1 led2 led3 gnd ref ledpg pgnd pwm1 led4 vled2' led4 con3 led board 1 2 3 4 5 6 led1 led2 led3 led4 vled1 vled2 r601 res en gnd_2
al1794ev1 user guide quad - channel current - ratio - optimized led driver with analog and pwm dimming al1794ev1 rev1 page 12 of 13 ju ly 2015 www.diodes.com bill of material # name q ty part number manufacturer description 1 u601 1 al1794 afe - 1 3 diodes inc 4 - channel led driver 2 u681 1 ap2204k - 3.3vtrg1 diodes inc wide - input (2.5v - 24v) 150ma uldo 3 c601 1 eca - 1hm101 panasonic e - cap 100uf 50v (8x11.5mm) 4 c602 1 eca - 1hm101 panasonic e - cap 100uf 50v (8x11.5mm) 5 c603 1 cc0603krx7r9bb104 yageo cap cer 0.1uf 50v x7r 0603 6 c621 1 cc0805krx7r9bb104 yageo cap cer 1.0uf 50v x7r 0805 7 c681 1 cc0805krx7r9bb104 yageo cap cer 1.0uf 50v x7r 0805 8 c682 1 cc0805zry5v6bb475 yageo cap cer 4.7uf 10v x7r 0805 9 r601 (rset) 1 rc0603jr - 0712kl yageo res 12k? 1/10w 5% 0603 smd 10 r602 1 rc0603jr - 0710kl yageo res 10k? 1/10w 5% 0603 smd 11 r607 1 rc0603jr - 0710kl yageo res 10k? 1/10w 5% 0603 smd 12 r608 1 rc0603jr - 0710kl yageo res 10k? 1/10w 5% 0603 smd 13 jp_en 1 800 - 10 - 002 - 10 - 001000 mill - max enable 2 pin sip header w/jumper 14 led_bar 1 800 - 10 - 006 - 10 - 001000 mill - max led emitter output i/o 6pin sip header 15 mcu1 1 800 - 10 - 010 - 10 - 001000 mill - max mcu i/o 10pin sip header 16 vled1 1 534 - 1598 - 2 mouser vled1 anode input, term 0.094x1/16 17 vled2 1 5 34 - 1598 - 2 mouser vled2 anode input, term 0.094x1/16 18 gnd 1 534 - 1598 - 2 mouser ground input, term 0.094x1/16
al1794ev1 user guide quad - channel current - ratio - optimized led driver with analog and pwm dimming al1794ev1 rev1 page 13 of 13 ju ly 2015 www.diodes.com important notice diodes incorporated makes no warranty of any kind, express or implied, with regards to this document, including , but not limited to, the implied warranties of merchantability and fitness for a particular purpose (and their equivalents under the laws of any jurisdiction). diodes incorporated and its subsidiaries reserve the right to make modifications, enhancemen ts, improvements, corrections or other changes without further notice to this document and any product described herein. diodes incorporated does not assume any liability arising out of the application or use of this document or any product described herei n; neither does diodes incorporated convey any license under its patent or trademark rights, nor the rights of others. any customer or user of this document or products described herein in such applications shall assume all risks of such use and will agre e to hold diodes incorporated and all the companies whose products are represented on diodes incorporated website, harmless against all damages. diodes incorporated does not warrant or accept any liability whatsoever in respect of any products purchased through unauthorized sales channel. should customers purchase or use diodes incorporated products for any unintended or unauthorized application, customers shall indemnify and hold diodes incorporated and its representatives harmless against all claims, d amages, expenses, and attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized application. products described herein may be covered by one or more united states, internati onal or foreign patents pending. product names and markings noted herein may also be covered by one or more united states, international or foreign trademarks. this document is written in english but may be translated into multiple languages for referenc e. only the english version of this document is the final and determinative format released by diodes incorporated. life support diodes incorporated products are specifically not authorized for use as critical components in life support devices or syste ms without the express written approval of the chief executive officer of diodes incorporated. as used herein: a. life support devices or systems are devices or systems which: 1. are intended to implant into the body, or 2. support or sustain life an d whose failure to perform when properly used in accordance with instru ctions for use provided in the labeling can be reasonably expected to result in significant injury to the user. b. a critical component is any component in a life support device or s ystem whose failure to perform can be re asonably expected to cause the failure of the life support device or to affect its safety or effectiveness. customers represent that they have all necessary expertise in the safety and regulatory ramifications of th eir life support devices or systems , and acknowledge and agree that they are solely responsible for all legal, regulatory and safety - related requirements concerning their products and any use of diodes incorporated products in such safety - critical, life support devices or systems, notwithst anding any devices - or systems - related information or support that may be provided by diodes incorporated. further, customers must fully indemnify diodes incorporated and its representatives against any damages arising out of the use of diod es incorporate d products in such safety - critical, life support devices or systems. copyright ? 201 5 , diodes incorporated www.diodes.com

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