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1 Version : A.003 Issue Date : 2008/05/12 File Name Total Pages : 24 : SP--A.003.doc 16-CHANNEL CONSTANT CURRENT LED DRIVER WITH PROGRAMMABLE PWM OUTPUTS 9-7F-1, Prosperity Road I, Science Based Industrial Park, Hsin-Chu, Taiwan 300, R.O.C.

2 16-CHANNEL CONSTANT CURRENT LED DRIVER WITH PROGRAMMABLE PWM OUTPUTS General Description is a 16-channel constant current sink LED driver. Each channel has adjustable 12-bits (4096 steps) grayscale PWM control current outputs. It incorporates shift registers, data latches, constant current circuitry with current value set by an external resistor, selectable oscillator source for PWM function, and built-in LED open detection circuit to detect error status. It is specifically designed for LED display or lighting applications. Features Constant-current outputs: 5mA to 90mA adjustable by one external resistor 12-bit PWM control current outputs for each channel Maximum output voltage: 17V Maximum clock frequency: 25MHz Selectable internal/external PWM reference clock PWM free-running capability (refresh rate (~4.4KHz) with internal oscillator (~ 18 MHz)) Build-in real-time LED open detection Package and pin assignment (except QFN32) compatible to pure LED drivers series (ST2221C, DM134/5/6, DM13C) Power supply voltage: 3.3V to 5.5V Applications Indoor/Outdoor LED Video Display LED Variable Message Signs (VMS) System LED Decorative Lighting Package Types SOP24, SOP24B, SSOP24, TSSOP24E (with exposed pad), QFN32 (with exposed pad) 16-channel 12-bit PWM Constant Current LED Driver Version:A.003 Page 1

3 Block Diagram OUT 0 OUT 1 OUT 15 VCC LED Open Detector (0) LED Open Detector (1) LED Open Detector (15) GND Internal Oscillator Constant Current Driver (0) Constant Current Driver (1) Constant Current Driver (15) REXT 12-bit Counter 12-bit PWM Generator (0) 12-bit PWM Generator (1) 12-bit PWM Generator (15) SOMODE /GCK LAT 12-bit Latch Register (0) 12-bit Latch Register (1) 12-bit Latch Register (15) DAI 12-bit Shift Register (0) 12-bit Shift Register (1) 12-bit Shift Register (15) DAO 16-channel 12-bit PWM Constant Current LED Driver Version:A.003 Page 2

4 Pin Connection GND DAI LAT OUT0 OUT1 OUT2 OUT3 OUT4 OUT5 OUT6 OUT SOP24 SOP24B SSOP24 TSSOP24E ( top view ) VCC REXT DAO SOMODE/GCK OUT 15 OUT 14 OUT 13 OUT 12 OUT 11 OUT 10 OUT 9 OUT 8 OUT10 OUT9 OUT8 GND GND OUT7 OUT6 OUT5 OUT11 REXT DAO SOMODE /GCK OUT15 OUT14 OUT13 OUT QFN ( bottom view ) OUT3 OUT4 OUT0 OUT1 OUT2 DAI LAT GND GND VCC VCC GND GND GND GND Pin Description PIN No. PIN NAME FUNCTION SOP24/SOP24B/SSOP24 /TSSOP24E: 1 TSSOP24E, QFN32: exposed pad QFN32: 1, 2, 5, 6, 7, 8, 20,21 GND Ground terminal. SOP24/SOP24B/SSOP24 /TSSOP24E: 2 QFN32: 9 DAI Serial data input terminal. SOP24/SOP24B/SSOP24 /TSSOP24E: 3 QFN32: 10 SOP24/SOP24B/SSOP24 /TSSOP24E: 4 QFN32: 11 SOP24/SOP24B/SSOP24/TSSOP24E: 5~20 QFN32: 12~19, 22~29 SOP24/SOP24B/SSOP24 /TSSOP24E: 21 QFN32: 30 SOP24/SOP24B/SSOP24 /TSSOP24E: 22 QFN32: 31 LAT OUT0~15 SOMODE /GCK DAO Synchronous clock input terminal for serial data transfer. Data is sampled at the rising edge of. Input terminal of data strobe: (level trigger) H means latch register keep data L means latch register gets data Sink constant-current outputs (open-drain). Serial Out Mode Selection(SOMODE) : H : DAO is shifted out and synchronized to falling edge of, L : DAO is shifted out and synchronized to rising edge of. Gray Scale Clock(GCK) : Input terminal for PWM operation. Serial data output terminal. SOP24/SOP24B/SSOP24 /TSSOP24E: 23 QFN32: 32 SOP24/SOP24B/SSOP24 /TSSOP24E: 24 QFN32: 3, 4 REXT VCC External resistors connected between REXT and GND for output current value setting. Supply voltage terminal. 16-channel 12-bit PWM Constant Current LED Driver Version:A.003 Page 3

5 Equivalent Circuit of Inputs and Outputs 1., DAI, LAT, SOMODE/GCK terminals 2. DAO terminals PCB Layout Consideration To connect an external resistor to REXT pin and ground can determine the maximum output current. If there is any disturbance occurred to REXT pin, the constant current output may be unstable or noisy. Since REXT (pin23), DAO (pin22), and SOMODE/GCK (pin21) are next to each other, the most possible interference is caused by DAO or SOMODE/GCK signal. Accordingly, it is recommended that adding some shielding area within the above pins in PCB layout, or laying the signal line of above pins on different PCB layer will prevent the noise problems effectively. 16-channel 12-bit PWM Constant Current LED Driver Version:A.003 Page 4

6 Maximum Ratings (Ta=25 C, Tj(max) = 150 C) CHARACTERISTIC SYMBOL RATING UNIT Supply Voltage VCC -0.3 ~ 7.0 V Input Voltage VIN -0.3 ~ VCC+0.3 V Output Current IOUT 100 ma Output Voltage VOUT -0.3 ~ 17 V Input Clock Frequency F 25 MHz GND Terminal Current IGND 1600 ma Power Dissipation ( 4 layer PCB, Ta=25 ) Thermal Resistance ( 4 layer PCB, Ta=25 ) PD Rth(j-a) 4.46 ( QFN32 ) 4.17 ( TSSOP24E ) 2.45 ( SOP24 ) 2.19 (SOP24B ) 1.79 ( SSOP24 ) 28.0 ( QFN32 ) 30.0 ( TSSOP24E) 51.0 (SOP24 ) 66.0 (SOP24B) 70.0 (SSOP24 ) Operating Temperature Top -40 ~ 85 C Storage Temperature Tstg -55 ~ 150 C Recommended Operating Condition CHARACTERISTIC SYMBOL CONDITION MIN. TYP. MAX. UNIT Supply Voltage VCC V Output Voltage VOUT Driver On * VCC Output Voltage VOUT Driver Off *2 17 Output Current Input Voltage IO OUTn 5 90 IOH VOH = VCC 0.4 V IOL VOL = 0.2 V VIH 0.8VCC VCC VCC = 3.3 V ~ 5.5V VIL VCC Input Clock Frequency F Single Chip Operation 25 Input PWM Frequency FGCK VCC = 3.3 V ~ 5.5V 25 LAT Pulse Width tw LAT 15 Pulse Width tw 15 Set-up Time for DAI tsetup(d) 10 Hold Time for DAI thold(d) VCC = 5.0V 10 Set-up Time for LAT tsetup(l) 10 Hold Time for LAT thold(l) 10 Internal Oscillator Frequency FOSC W C/W V ma V MHz ns MHz *1 Notice that the power dissipation is limited to its package and ambient temperature. *2 The driver output voltage including any overshoot stress has to be compliant with the maximum voltage (17V). 16-channel 12-bit PWM Constant Current LED Driver Version:A.003 Page 5

7 Electrical Characteristics (VCC = 5.0 V, Ta = 25 C unless otherwise noted) CHARACTERISTIC SYMBOL CONDITION MIN. TYP. MAX. UNIT Input Voltage H Level VIH CMOS logic level 0.8*VCC VCC Input Voltage L Level VIL CMOS logic level GND 0.2*VCC V Output Leakage Current IOL VOH = 17 V ±1.0 ua Output Voltage (S-OUT) VOL IOL = 1.25 ma 0.2 VOH IOH= 1.2 ma VCC-0.4 V Output Current Skew (Channel-to-Channel) *1 IOL1 ±3 % VOUT = 1.0 V Rrext = 2.2 KΩ Output Current Skew (Chip-to-Chip) *2 IOL ma Output Voltage Regulation % / VOUT Rrext = 2.2 KΩ VOUT = 1 V ~ 3 V ±0.1 ±0.5 % / V Supply Voltage Regulation % / VCC Rrext = 2.2 KΩ ±1 ±4 LED Open Detection Threshold V(od) all outputs turn on 0.3 V I DD(off) power on all pins are open unless VCC and GND (fee-running mode) Supply Current *3 I DD(off) I DD(on) I DD(on) I DD(on) power on all pins are open unless VCC and GND (external GCK mode) input signal is static Rrext = 12.4 KΩ all outputs turn off input signal is static Rrext = 2.2 KΩ all outputs turn off input signal is static Rrext = 570 Ω all outputs turn off ma *1 Channel-to-channel skew is defined as the ratio between (any Iout average Iout) and average Iout, where average Iout = (Imax + Imin) / 2. *2 Chip-to-Chip skew is defined as the range into which any output current of any IC falls. *3 IO excluded. 16-channel 12-bit PWM Constant Current LED Driver Version:A.003 Page 6

8 Electrical Characteristics (VCC = 3.3 V, Ta = 25 C unless otherwise noted) CHARACTERISTIC SYMBOL CONDITION MIN. TYP. MAX. UNIT Input Voltage H Level VIH CMOS logic level 0.8*VCC VCC Input Voltage L Level VIL CMOS logic level GND 0.2*CC V Output Leakage Current IOL VOH = 17 V ±1.0 ua Output Voltage (S-OUT) VOL IOL = 1.25 ma 0.2 VOH IOH= 1.2mA VCC-0.4 V Output Current Skew (Channel-to-Channel) *1 IOL1 ±3 % VOUT = 1.0 V Rrext = 2.2 KΩ Output Current Skew (Chip-to-Chip) *2 IOL ma Output Voltage Regulation % / VOUT Rrext = 2.2 KΩ VOUT = 1 V ~ 3 V ±0.1 ±0.5 % / V Supply Voltage Regulation % / VCC Rrext = 2.2 KΩ ±1 ±4 LED Open Detection Threshold V(od) all outputs turn on 0.3 V I DD(off) power on all pins are open unless VCC and GND (fee-running mode) 3.8 Supply Current *3 I DD(off) I DD(on) I DD(on) I DD(on) power on all pins are open unless VCC and GND (external GCK mode) input signal is static Rrext = 12.4 KΩ all outputs turn off input signal is static Rrext = 2.2 KΩ all outputs turn off input signal is static Rrext = 570 Ω all outputs turn off ma *1 Channel-to-channel skew is defined as the ratio between (any Iout average Iout) and average Iout, where average Iout = (Imax + Imin) / 2. *2 Chip-to-Chip skew is defined as the range into which any output current of any IC falls. *3 IO excluded. 16-channel 12-bit PWM Constant Current LED Driver Version:A.003 Page 7

9 Switching Characteristics (VCC = 5.0V, Ta = 25 C unless otherwise noted) Propagation Delay ( L to H ) Propagation Delay ( H to L ) CHARACTERISTIC SYMBOL CONDITION MIN. TYP. MAX. UNIT GCK-to-OUT (rising edg)-to-dao tplh (falling edg)-to-dao VIH = VCC 14.4 GCK-to-OUT (rising edg)-to-dao tphl VIL = GND (falling edg)-to-dao Rrext = 2.3 KΩ 9.7 Output Current Rise Time tor VL = 5.0 V 18 Output Current Fall Time tof 6.96 CL = 13 pf Output to output Delay Time Unit td 33 Output Current (Propagation Delay after LAT trigger) top *1 ns 288 us Switching Characteristics (VCC = 3.3V, Ta = 25 C unless otherwise noted) CHARACTERISTIC SYMBOL CONDITION MIN. TYP. MAX. UNIT GCK-to-OUT 48.8 Propagation Delay (rising edg)-to-dao tplh 21.2 ( L to H ) (falling edg)-to-dao 18.3 VIH = VCC GCK-to-OUT 29.6 Propagation Delay VIL = GND (rising edg)-to-dao tphl 17.6 ( H to L ) (falling edg)-to-dao Rrext = 2.3 KΩ 14.4 Output Current Rise Time tor VL = 3.3 V 20 Output Current Fall Time tof CL = 13 pf 8.25 Output to output Delay Time Unit td 34 Output Current (Propagation Delay after LAT trigger) top *1 ns 288 us VL VCC A CL CL CL CL DAI OUTn REXT LAT SOMODE DAO /GCK GND CL Rrext Switching Characteristics Test Circuit *1 Reload the new PWM data at the end of the last PWM frame. 16-channel 12-bit PWM Constant Current LED Driver Version:A.003 Page 8

10 Constant-Current Output Constant-current value(iout *1 ) of each output channel is set by an external resistor connected between the REXT pin and GND. The current scale ranging can be adjusted from 5mA to 90mA by varying the resistor value. The reference voltage of REXT terminal (Vrext) is approximately 1.23V. The output current value is calculated by the following equation: Iout(mA) M Output Current as a Functiono Rext value Iout(mA) Vrext (V) Iout (ma) ~ M Rrext (KΩ) Rext(KΩ) Output Current as a Function of Output Voltage Iout (ma) Vout (V) In order to obtain a good performance of constant-current output, a suitable output voltage is necessary. Users can get related information about the minimum output voltage above. *1 Iout is typical current value setting under 100% PWM duty cycle and 95 D GBC Value. 16-channel 12-bit PWM Constant Current LED Driver Version:A.003 Page 9

11 Serial Data Interface The serial-in data (DAI) will be clocked into bit shift registers synchronized on the rising edge of the clock (). The data will be transferred into the bit latch registers when the strobe signal ( LAT ) is kept at high level (level trigger); otherwise, the data will be held. The latch pulse should be sent after the falling edge of the last clock within a frame data. The trigger timing of the serial-out data (DAO) will be shifted out on synchronization to the rising edge of the clock if serial out selection (SOMODE) is kept at low level. And if serial out selection (SOMODE) is kept at high level, the serial-out data (DAO) will be shifted out on synchronization to the falling edge of the clock (). Input Data Format LED Open Detection provides a real time monitor of LED open detection function without extra components or circuit design. It will be identified as a LED open failure when the output is turned on but the output voltage is below 0.3V. The test result of each channel will write to its correspondent shift register which is in LSB position (D 15 [0], D 14 [0],., D 0 [0]) while strobe signal is active. User can refer to timing diagram on page13. Detecting report could be retrieved from serial-out (DAO) data. If the system reads 1 back, that indicates LED is in normal status. But if 0 was retrieved then LED open failure has occurred. In order to make sure LED open detection function is in well operating condition, it is recommended that all the luminance data are wrote to 1 then almost turning on the outputs during detection process. 16-channel 12-bit PWM Constant Current LED Driver Version:A.003 Page 10

12 Serial-out Data Format shift out first OUT 15 D 15 [11] D 15 [10] D 15 [9] D 15 [8] D 15 [7] D 15 [6] D 15 [5] D 15 [4] D 15 [3] D 15 [2] D 15 [1] E[15] MSB LSB OUT 14 D 14 [11] D 14 [10] D 14 [9] D 14 [8] D 14 [7] D 14 [6] D 14 [5] D 14 [4] D 14 [3] D 14 [2] D 14 [1] E[14] MSB LSB OUT 0 D 0 [11] D 0 [10] D 0 [9] D 0 [8] D 0 [7] D 0 [6] D 0 [5] D 0 [4] D 0 [3] D 0 [2] D 0 [1] E[0] MSB LSB *E[15], E[14],,E[0] are Error Message of LED Open Detection. `1'is normal, and `0'is abnormal. Selection of Internal/External PWM Frequency The default operation mode is the free-running PWM signal generated by internal oscillator after power-on. Users could switch internal to external PWM frequency source by following timing sequence. There are two alternative options could be selected. The option 1 shows three rising edge of latch pulses ( LAT ) when the clock () kept at high level then two rising edge of clock () pulses when the latch pulse ( LAT ) kept at high level. Then the SOMODE/GCK pin could input external frequency to operate PWM function. The option 2 shows four rising edge of latch pulses( LAT ) when clock() kept at high level then sending three rising edge of clock () signal, while latch( LAT ) signal kept high level at the same time. Meanwhile the GCK external mode can be set back to the free-running mode. Notice that when internal RESET at low level, all the shift registers in will be cleared (Kept at Low level) and all output current will be off immediately. LAT Normal Operation t LAT LAT RESET (internal) RESET (internal) t t Option 1 : Timing Combination to set up external GCK mode Option 2 : Timing Combination to set up free-running mode 16-channel 12-bit PWM Constant Current LED Driver Version:A.003 Page 11

13 Timing Diagram 1. -DAI, DAO (SOMODE = L at free-running mode, or external GCK mode) tw tw 50% 50% 50% 50% tsetup(d) thold(d) DAI 50% 50% DAO 50% 50% tplh tphl 2., DAO (SOMODE = H at free-running mode) tw tw 50% 50% 50% 50% DAO 50% 50% tplh tphl 3. -LAT 50% 50% tsetup(l) t hold(l) LAT 50% 50% twlat 4. Output to Output Delay Time Unit (n=2,3,4,5,6,7,10,11,12,13,14,15) OUTn 50% t d OUTn-2 50% 5. GCK-OUT 0 GCK 50% 50% OUT 0 50% 50% tplh tphl 16-channel 12-bit PWM Constant Current LED Driver Version:A.003 Page 12

14 5. Timing Diagram (free-running mode switch to external GCK mode) DAI D A [2] D A [1] 1 D B [191] D B [190] D B [1] D B [0] D A [0] D C [191] D C [190] D C [0] D B [2] D D [191] D [190] high low 1 DAO *1 E[0]* 2 E[0]* 2 E[0]* 2 D Z [1] D A [1] D A [191] D B [191] D A [190] D C [191] D C [190] D C [189] 0 LAT *3 high low SOMODE *4 /GCK *5 <1frame* x GCK* OUTn (current ) on Frame Data Z Frame Data A Frame Data C* 8 off *1 DAO is shifted out on synchronization to rising / falling edge of according to SOMODE is`l'/`h'. *2 E[0] is the error message of LED open detection. *3 LAT is level trigger, not edge trigger. *4 SOMODE function work in free-running mode. *5 While switching to external GCK mode, all registers in will be reset simultaneously. *6 Starting the new PWM frame after the last PWM period finish completely. *7 While switching to external GCK mode, outputs will be active after 4096 GCK pulse. *8 When using external frequency for PWM operation, the PWM refresh rate (frame rate) can be calculated by following equation: Refresh Rate (Hz) = Input GCK Frequency (Hz) Total PWM resolution ( 2 12 ) For example, if the refresh rate in display system is higher than 60Hz, the input GCK frequency must be higher than 246kHz. 16-channel 12-bit PWM Constant Current LED Driver Version:A.003 Page 13

15 Timing Diagram (external GCK mode switch to free-running mode) DAI DAO LAT SOMODE / GCK OUTn (current ) D D [0] 192 D D [191] Frame Data C D E [191] D E [190] D E [0] D F [191] D F [190] D[0] F [1 91 ] [1 89 ] [19 1 ] D E D E [1 90 ] D E D D [190] D D [189] D F One free-running PWM cycle Frame Data D D G [191] D G [190] 1 2 D F [190] D F [189] Frame Data F 1 0 high low 1 0 high low 1 0 on off 16-channel 12-bit PWM Constant Current LED Driver Version:A.003 Page 14

16 Global Brightness Control has no built-in global brightness control feature. In order to obtain a lower resolution of global brightness control effect, two methods could be utilized. Here show different ways to adjust the Rrext value or voltage drop across the external resistor. Please see the reference circuit below: Output to Output Delay has build-in output to output delay with a special arrangement. This arrangement help chip avoid noise cause by large current during channels switching. The arrangement details are shown as following table. Channel Delay units channel 12-bit PWM Constant Current LED Driver Version:A.003 Page 15

17 Power Dissipation The power dissipation of a semiconductor chip is limited to its package and ambient temperature, in which the device requires the maximum output current calculated for given operating conditions. The maximum allowable power consumption can be calculated by the following equation: Pd(max)(Watt) = Tj(junction temperature)(max)( C) Ta(ambient temperature)( C) Rth(junction-to-air thermal resistance)( C/Watt) The relationship between power dissipation and operating temperature can be refer to the figure below: Power Dissipation Pd(W) QFN32 Tj(max)=150 C Rth(QFN32)=28.0 C/Watt TSSOP24 Rth(TSSOP24)=30.0 C/Watt Rth(SOP24)=51.0 C/Watt SOP24 Rth(SOP24B)=57.0 C/Watt SOP24B Rth(SSOP24)=70.0 C/Watt SSOP Ambient Temperature Ta ( ) The power consumption of IC can be determined by the following equation and should be less than the maximum allowable power dissipation: 16-channel 12-bit PWM Constant Current LED Driver Version:A.003 Page 16

18 Typical Application 16-channel 12-bit PWM Constant Current LED Driver Version:A.003 Page 17

19 Package Outline Dimension -SSOP D E E A C GAUGE PLANE A2 A b e SEATING PLANE L L1 A1 DETAIL A DIMENSIONS IN INCH DIMENSIONS IN MM SYMBOLS MIN. MAX. MIN. MAX. A A A b C D E E e BSC BSC L L BSC BSC Θ channel 12-bit PWM Constant Current LED Driver Version:A.003 Page 18

20 Package Outline Dimension -SOPB DIMENSIONS IN INCH DIMENSIONS IN MM SYMBOLS MIN. MAX. MIN. MAX. A A A b c D E e BSC BSC E L θ channel 12-bit PWM Constant Current LED Driver Version:A.003 Page 19

21 Package Outline Dimension -SOP E H b e D A 0.01 inch L 0.004MAX. A1 GAUGE PLANE SEATING PLANE DIMENSIONS IN INCH DIMENSIONS IN MM SYMBOLS MIN. MAX. MIN. MAX. A A b BSC BSC D E e BSC BSC H L Θ channel 12-bit PWM Constant Current LED Driver Version:A.003 Page 20

22 Package Outline Dimension -TSSOP (exposed pad) D1 E1 E E e b S D 0.25mm A2 A L GAUGE PLANE SEATING PLANE 0.05 A1 L1 DIMENSIONS IN INCH DIMENSIONS IN MM SYMBOLS MIN. MAX. MIN. MAX. A A A b D E E BSC BSC e BSC BSC L REF REF. L S Θ E D channel 12-bit PWM Constant Current LED Driver Version:A.003 Page 21

23 Package Outline Dimension -QFN (exposed pad) D b 24 1 CO.35x45 E 61cm e 17 8 A D A3 L K A 0.08 E2 DIMENSIONS IN INCH DIMENSIONS IN MM SYMBOLS MIN. MAX. MIN. MAX. A A A REF REF. b D E e BSC BSC L K D E Note: 1.DIMENSIONING AND TOLERANCING CONFORM TO ASME Y145.5M REFER TO JEDEC STD. MO-220 WHHD-2 ISSUE A 16-channel 12-bit PWM Constant Current LED Driver Version:A.003 Page 22

24 The products listed herein are designed for ordinary electronic applications, such as electrical appliances, audio-visual equipment, communications devices and so on. Hence, it is advisable that the devices should not be used in medical instruments, surgical implants, aerospace machinery, nuclear power control systems, disaster/crime-prevention equipment and the like. Misusing those products may directly or indirectly endanger human life, or cause injury and property loss. Silicon Touch Technology, Inc. will not take any responsibilities regarding the misusage of the products mentioned above. Anyone who purchases any products described herein with the above-mentioned intention or with such misused applications should accept full responsibility and indemnify. Silicon Touch Technology, Inc. and its distributors and all their officers and employees shall defend jointly and severally against any and all claims and litigation and all damages, cost and expenses associated with such intention and manipulation. 16-channel 12-bit PWM Constant Current LED Driver Version:A.003 Page 23

Microsoft Word - SP-DM13A-A.003.doc

Microsoft Word - SP-DM13A-A.003.doc Version : A.003 Issue Date : 2007/12/12 File Name Total Pages : 20 : SP--A.003.doc 16-bit Constant Current LED Driver 新竹市科學園區展業一路 9 號 7 樓之 1 9-7F-1, Prosperity Road I, Science Based Industrial Park, Hsin-Chu,