Macroblock Datasheet MBI5171 8-Bit Constant Current LED Driver with LED Error Detection and Run-Time Current Adjustment Features M BMBI5171CN I5 0 0 1 C N MBI5168CN MBI5001CN l Compatible with MBI5168 in electrical characteristics and package l Exploiting Share-I-O™ technique to provide two operation modes: - Normal Mode with the same functionality as MB5168 - Special Mode to detect individual LED errors, like MBI5169 and program output current gain, like MBI5170 P-DIP16-300-2.54 Weight：1.02g MBI5171CD MBI5168CD MBI5001CD l 8 constant-current output channels l Constant output current invariant to load voltage change l Constant output current range: 5 -120 mA l Excellent output current accuracy, SOP16-150-1.27 Weight：0.13g between channels: < ±3% (max.), and between ICs: < ±6% (max.) MBI5168CDW MBI5171CDW l Output current adjusted through an external resistor l Fast response of output current, MBI5001CD OE (min.): 200 ns @Iout< 60mA OE (min.): 400 ns @Iout= 60~100mA l 25MHz clock frequency l Schmitt trigger input l 3.3~ 5V supply voltage l 256-step run-time programmable output current gain SOP16-300-1.27 Weight：0.37g MBI5168CP MBI5171CP suitable for white balance application SSOP16-150-0.64 Weight：0.07g Current Accuracy Conditions Between Channels Between ICs < ±3% < ±6% IOUT = 10 ~ 100 mA, VDS = 0.8V, VDD= 5.0V Macroblock, Inc. 2004 Floor 6-4, No.18, Pu-Ting Rd., Hsinchu, Taiwan 30077, ROC. TEL: +886-3-579-0068, FAX: +886-3-579-7534, E-mail: [email protected] -1August 2004, VA.00 MBI5171 8-Bit Constant Current LED Driver with LED Error Detection and Run-Time Current Adjustment Product Description MBI5171 succeeds MBI5168 and also exploits PrecisionDrive™ technology to enhance its output characteristics. Furthermore, MBI5171 uses the idea of Share-I-O™ technology to make MBI5171 backward compatible with MBI5168 in both package and electrical characteristics and extend its functionality for LED load Error Detection and run-time LED current gain control in LED display systems, especially LED traffic sign applications. MBI5171 contains an 8-bit Shift Register and an 8-bit Output Latch, which convert serial input data into parallel output format. At MBI5171 output stages, eight regulated current ports are designed to provide uniform and constant current sinks with small skew between ports for driving LED’s within a wide range of forward voltage (Vf) variations. Users may adjust the output current from 5 mA to 120 mA with an external resistor R ext, which gives users flexibility in controlling the light intensity of LED’s. MBI5171 guarantees to endure maximum 17V at the output ports. Besides, the high clock frequency up to 25 MHz also satisfies the system requirements of high volume data transmission. MBI5171 extends its functionality to provide one Special Mode in which two functions are included, Error Detection and Current Gain Control, by means of the Share-I-O™ technique on pins LE and OE , without any extra pins. Thus, MBI5171 could be a drop-in replacement of MBI5168. The printed circuit board originally designed for MBI5168 may be also applied to MBI5171. In MBI5171 there are two operation modes and three phases: Normal Mode phase, Mode Switching transition phase, and Special Mode phase. The signal on the multiple function pin OE / SW / ED would be monitored. Once an one-clock-wide short pulse appears on the pin OE / SW / ED , MBI5171 would enter the Mode Switching phase. At this moment, the voltage level on the pin LE/MOD/CA is used for determining the next mode to which MBI5171 is going to switch. In the Normal Mode phase, MBI5171 has exactly the same functionality with MBI5168. The serial data could be transferred into MBI5171 via the pin SDI, shifted in the Shift Register, and go out via the pin SDO. The LE/MOD/CA can latch the serial data in the Shift Register to the Output Latch. OE / SW / ED would enable the output drivers to sink current. In the Special Mode phase, the low-voltage-level signal OE / SW / ED can enable output channels and detect the status of the output current to tell if the driving current level is enough or not. The detected error status would be loaded into the 8-bit Shift Register and be shifted out via the pin SDO along with the signal CLK. Then system controller could read the error status and know whether the LED’s are properly lit or not. On the other hand, in the Special Mode phase MBI5171 also allows users to adjust the output current level by setting a run-time programmable Configuration Code. The code is sent into MBI5171 via the pin SDI. The positive pulse of LE/MOD/CA would latch the code in the Shift Register into a built-in 8-bit Configuration Latch, instead of the Output Latch. The code would affect the voltage at the terminal R-EXT and control the output current regulator. The output current could be adjusted finely by a gain ranging (1/12) to (127/128) in 256 steps. Hence, the current skew between IC’s can be compensated within less than 1% and this feature is suitable for white balancing in LED color display panels. Users can get detailed ideas about how MBI5171 works in the section Operation Principle. -2- August 2004, VA.00 8-Bit Constant Current LED Driver with LED Error Detection and Run-Time Current Adjustment MBI5171 Pin Assignment GND SDI CLK LE/MOD/CA OUT 0 OUT1 OUT2 OUT3 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 VDD R-EXT SDO OE/SW/ED OUT7 OUT6 OUT5 OUT4 Terminal Description Pin No. Pin Name Function 1 GND Ground terminal for control logic and current sinks 2 SDI Serial-data input to the Shift Register 3 CLK Clock input terminal for data shift at the rising edge Output channel data strobe input terminal: in the Normal Mode phase, serial data in the Shift Register is transferred to the respective Output Latch when LE/MOD/CA is high; the data is latched inside the Output Latch when LE/MOD/CA goes low. If the data in the Output Latch is “1” (High), the respective output channel will be enabled after OE / SW / ED is pulled down to low. Mode selection input terminal: in the Mode Switching phase, LE/MOD/CA couldn’t strobe serial data but its level is used for determining the next mode to which MBI5171 is going to switch. When LE/MOD/CA is high, the next mode is the Special Mode; when low, the next mode is the Normal Mode. Configuration data strobe input terminal: in the Special Mode phase, serial data is latched into the Configuration Latch, instead of the Output Latch in the Normal Mode. The serial data here is regarded as the Configuration Code, which affect the output current level of all channels.(See Operation Principle) 4 LE/MOD/CA 5-12 OUT0 ~ OUT7 Constant current output terminals OE / SW / ED Output enable terminal: no matter in what phase MBI5171 operates, the signal OE / SW / ED can always enable output drivers to sink current. When its level is (active) low, the output drivers are enabled; when high, all output drivers are turned OFF (blanked). Mode switching trigger terminal: an one-clock-wide short pulse signal of OE / SW / ED could put MBI5171 into the Mode Switching phase. Error detection enable terminal: in the Special Mode phase, the active low signal OE / SW / ED can make MBI5171 not just enable output drivers but detect LED load error status. The detected error status would be stored into the Shift Register. (See Operation Principle) 13 14 SDO Serial-data output to the following SDI of the next driver IC 15 R-EXT Input terminal used for connecting an external resistor in order to set up the current level of all output ports 16 VDD Supply voltage terminal -3- August 2004, VA.00 8-Bit Constant Current LED Driver with LED Error Detection and Run-Time Current Adjustment MBI5171 In MBI5171, the relationship between the functions of pins 4 and 13 and the operation phases are listed below: Pin No. 4 13 Pin Name LE/MOD/CA OE / SW / ED Function Normal Mode Mode Switching Special Mode LE: latching serial data into the Output Latch Yes No No MOD: mode selection No Yes No CA: latching serial data into the Configuration Latch No No Yes OE : enabling the current output drivers Yes Yes Yes SW: entering the Mode Switching phase Yes Yes Yes ED : enabling error detection and storing results into the Shift Register No No Yes -4- August 2004, VA.00 8-Bit Constant Current LED Driver with LED Error Detection and Run-Time Current Adjustment MBI5171 Block Diagram OUT0 R-EXT OUT1 OUT6 OUT7 IOUT Regulator VDD OE /SW/ ED 8-Bit Output Driver Control Logic LE/MOD/CA 8 8 GND 8-Bit Output Latch 8-Bit Configuration Latch CLK 8 8 8-Bit Shift Register SDI SDO 8 Equivalent Circuits of Inputs and Outputs OE/SW/ ED Terminal LE/MOD/CA Terminal VDD VDD LE/MOD/CA OE/SW/ ED CLK, SDI Terminal SDO Terminal VDD VDD SDO CLK, SDI -5- August 2004, VA.00 8-Bit Constant Current LED Driver with LED Error Detection and Run-Time Current Adjustment MBI5171 Timing Diagram Normal Mode N= 0 1 2 3 4 5 6 7 CLK SDI LE/MOD/CA OE/SW/ED OFF OUT0 ON OFF OUT1 ON OFF OUT2 ON OFF OUT3 ON OFF OUT6 ON OFF OUT7 ON SDO : don’t care Truth Table (In Normal Mode) CLK OUT0 … OUT5 … OUT 7 SDO Dn ….. Dn - 5 …. Dn - 7 Dn-7 Dn+1 No Change Dn-6 L Dn+2 Dn + 2 …. Dn - 3 …. Dn - 5 Dn-5 X L Dn+3 Dn + 2 …. Dn - 3 …. Dn - 5 Dn-5 X H Dn+3 Off Dn-5 LE/MOD/CA OE/SW/ ED SDI H L Dn L L H -6- August 2004, VA.00 8-Bit Constant Current LED Driver with LED Error Detection and Run-Time Current Adjustment MBI5171 Switching to Special Mode 1 2 3 4 5 CLK OE/SW/ED 1 0 1 1 1 LE/MOD/CA 0 0 0 1 0 The above shows an example of the signal sequence that can set the next operation mode of MBI5171 to be the Special Mode. The LE/MOD/CA active pulse here would not latch any serial data. Note: After entering the Special Mode, MBI5171 can detect LED error and adjust current gain. Writing Configuration Code (In Special Mode) N=0 1 2 3 4 6 5 7 CLK LE/MOD/CA SDI 8-Bit Bit7 Bit6 Configuration Bit5 Bit4 Bit3 Bit2 Code Bit1 Bit0 In the Special Mode, by sending the positive pulse of LE/MOD/CA, the content of the Shift Register with a Configuration Code will be written to the 8-bit Configuration Latch. Reading Error Status Code (In Special Mode) CLK At least 2 μs OE/SW/ED SDO Error Status Code Bit7 Bit6 Bit5 Bit4 : don’t care Bit3 When MBI5171 is working in the Special Mode, the above signal sequence example can let a system controller read the Error Status codes via the pin SDO. -7- August 2004, VA.00 8-Bit Constant Current LED Driver with LED Error Detection and Run-Time Current Adjustment MBI5171 Switching to Normal Mode 3 5 1 2 OE/SW/ED 1 0 1 1 1 LE/MOD/CA 0 0 0 0 0 4 CLK Voltage “Low” The above signal sequence example can make MBI5171 operate in the Normal Mode. Note: If users want to know the detailed process for each of the above examples, please refer to the contents in Operation Principle. -8- August 2004, VA.00 8-Bit Constant Current LED Driver with LED Error Detection and Run-Time Current Adjustment MBI5171 Maximum Ratings Characteristics Symbol Rating Unit Supply Voltage VDD 0 ~ 7.0 V Input Voltage VIN -0.4 ~ VDD + 0.4 V Output Current IOUT +120 mA Output Voltage VDS -0.5 ~ +20 V Clock Frequency FCLK 25 MHz GND Terminal Current IGND 1000 mA CN – type Power Dissipation (On PCB, Ta=25°C) Thermal Resistance (On PCB, Ta=25°C) 2.03 CD – type PD CDW – type 1.46 2.03 CP – type 1.32 CN – type 61.65 CD – type Rth(j-a) CDW – type CP – type 85.82 61.63 W °C/W 94.91 Operating Temperature Topr -40 ~ +85 °C Storage Temperature Tstg -55 ~ +150 °C -9- August 2004, VA.00 8-Bit Constant Current LED Driver with LED Error Detection and Run-Time Current Adjustment MBI5171 Recommended Operating Conditions Characteristics Symbol Condition Min. Typ. Max. Unit Supply Voltage VDD - 4.5 5.0 5.5 V Output Voltage VDS OUT0 ~ OUT7 - - 17.0 V IOUT OUT0 ~ OUT7 CM*=1, VDD =5V 5 - 120 mA IOUT OUT0 ~ OUT7 , CM*=0, VDD =5V 5 - 40 mA IOH SDO - - -1.0 mA IOL SDO - - 1.0 mA 0.7VDD - VDD+0.3 V -0.3 - 0.3VDD V 20 - - ns 5 - - ns Output Current VIH Input Voltage VIL CLK, OE/SW/ED LE/MOD, and SDI CLK, OE/SW/ED , LE/MOD, and SDI CLK Pulse Width tw(CLK) Setup Time for SDI tsu(D) Hold Time for SDI th(D) 10 - - ns LE/MOD/CA Pulse Width tw(L) 20 - - ns Setup Time for LE/MOD/CA tsu(L) 5 - - ns Hold Time for LE/MOD/CA th(L) 10 - - ns Setup Time for LE/MOD/CA tsu(MOD) 5 - - ns Hold Time for LE/MOD/CA th(MOD) - For data strobe In Mode Switching 10 - - ns tw(SW) To trigger Mode Switching 20 - - ns tw(OE) Iout < 60mA 200 - - ns tw(OE) Iout = 60~100mA 400 - - ns tw(ED) When detecting LED error status 2010 - - ns Setup Time for Correctly-Generated Error Status Code ** tsu(ER) When detecting LED error status 2000 - - ns Setup Time for OE/SW/ED tsu(SW) 5 - - ns Hold Time for OE/SW/ED th(SW) 10 - - ns Clock Frequency FCLK - - 25 MHz OE/SW/ED Pulse Width To trigger Mode Switching or when detecting LED error status Cascade Operation (VDD= 5.0V) * CM is one bit in configuration code and called as “Current Multiplier.” It would affect the ratio of IOUT to Irext. The detail information could be found in the section Operation Principle. ** In the Error Detection mode, when OE/SW/ED is pulled down to LOW for enabling output drivers and error detection, the output drivers must be enabled for at least 2us so that the error status code could be correctly generated. See Operation Principle and Timing Waveform. - 10 - August 2004, VA.00 8-Bit Constant Current LED Driver with LED Error Detection and Run-Time Current Adjustment MBI5171 Electrical Characteristics(VDD= 5.0V) Characteristics Symbol Condition Min. Typ. Max. Unit Supply Voltage VDD - 4.5 5.0 5.5 V Output Voltage VDS OUT0 ~ OUT7 - - 17.0 V IOUT Test Circuit for Electrical Characteristics 5 - 120 mA IOH SDO - - -1.0 mA IOL SDO - - 1.0 mA “H” level VIH Ta = -40~85ºC 0.7VDD - VDD V “L” level VIL Ta = -40~85ºC GND - 0.3VDD V VDS=17.0V and channel off - - 0.5 μA VOL IOL=+1.0mA - - 0.4 V VOH IOH=-1.0mA 4.6 - - V IOUT1 VDS = 0.5V; Rext = 744Ω; CG* = 0.992 - 25.0 - mA - ±1 ±3 % - 50.0 - mA - ±1 ±3 % - 100 - mA dIOUT3 IOUT = 100mA, VDS ≥ 0.8V - ±1 ±3 % Output Current Input Voltage Output Leakage Current Output Voltage SDO Output Current 1 Current Skew (between channels) Output Current 2 dIOUT1 IOUT = 25mA, VDS ≥ 0.5V IOUT2 Current Skew (between channels) Output Current 3 dIOUT2 IOUT = 50mA, VDS ≥ 0.6V IOUT3 Current Skew VDS = 0.6V; Rext = 372Ω; CG* = 0.992 VDS = 0.8V; Rext = 186Ω; CG* = 0.992 (between channels) Output Current vs. Output Voltage Regulation Output Current vs. Supply Voltage Regulation %/dVDS VDS within 1.0V and 3.0V - ±0.1 - %/V %/dVDD VDD within 4.5V and 5.5V - ±1 - %/V Pull-up Resistance RIN(up) OE/SW/ED 250 500 800 KΩ RIN(down) LE/MOD/CA 250 500 800 KΩ Pull-down Resistance Threshold Current for Error Detection** Iout, Th1 Rext=744 Ω, CG* = 0.992, Iout, target = 25mA - - 24.9 mA Iout, Th2 Rext=372 Ω, CG* = 0.992, Iout, target = 50mA - - 40 mA Iout, Th3 Rext=186 Ω, CG* = 0.992, Iout, target = 100mA - - 70 mA CG= 0.992 - 3.3 - IDD(off) 0 Rext=Open, “OFF” Supply Current “ON” OUT0 ~ OUT7 =Off; IDD(off) 1 Rext=744 Ω, OUT0 ~ OUT7 =Off; CG= 0.992 - 5.9 - IDD(off) 2 Rext=372 Ω, OUT0 ~ OUT7 =Off; CG= 0.992 - 8.5 - IDD(off) 3 Rext=186 Ω, OUT0 ~ OUT7 =Off; CG= 0.992 - 13.7 - IDD(on) 1 Rext=744 Ω, OUT0 ~ OUT7 =On; CG= 0.992 - 5.9 - IDD(on) 2 Rext=372 Ω, OUT0 ~ OUT7 =On; CG= 0.992 - 8.5 - IDD(on) 3 Rext=186 Ω, OUT0 ~ OUT7 =On; CG= 0.992 - 13.7 - - 11 - mA August 2004, VA.00 MBI5171 8-Bit Constant Current LED Driver with LED Error Detection and Run-Time Current Adjustment * In the above table, CG is the programmable current gain. The detail description could be found in the section Operation Principle. ** To effectively detect the load open-circuit error at the output ports, MBI5171 has a built-in current detection circuit. The current detection circuit will detect the effective current Iout, effective and compare it with the threshold current Iout, Th. If Iout, effective is less than the threshold current Iout, Th, an error flag (LOW) will be asserted and stored into the built-in Shift Register. Each combination of external resistor Rext and CG would determine a target output current Iout, target, which has a corresponding threshold current Iout, Th. To bias LED operation point properly and detect LED errors, there is a minimum effective output current requirement for each Rext, such as Iout, Th1, Iout, Th2, and Iout, Th3. - 12 - August 2004, VA.00 8-Bit Constant Current LED Driver with LED Error Detection and Run-Time Current Adjustment MBI5171 Electrical Characteristics(VDD= 3.3V) Characteristics Symbol Condition Min. Typ. Max. Unit Supply Voltage VDD - 3.0 3.3 3.6 V Output Voltage VDS OUT0 ~ OUT7 - - 17.0 V IOUT Test Circuit for Electrical Characteristics 5 - 120 mA IOH SDO - - -1.0 mA IOL SDO - - 1.0 mA “H” level VIH Ta = -40~85ºC 0.7VDD - VDD V “L” level VIL Ta = -40~85ºC GND - 0.3VDD V VDS=17.0V and channel off - - 0.5 μA VOL IOL=+1.0mA - - 0.4 V VOH IOH=-1.0mA 2.9 - - V IOUT1 VDS = 0.5V; Rext = 744Ω; CG= 0.992 - 25.0 - mA dIOUT1 IOUT = 25mA VDS ≥ 0.5V - ±1 ±3 % IOUT2 VDS = 0.6V; Rext = 372Ω; CG= 0.992 - 50.0 - mA dIOUT2 IOUT = 50mA VDS ≥ 0.6V - ±1 ±3 % Output Current Input Voltage Output Leakage Current Output Voltage SDO Output Current 1 Current Skew (between channels) Output Current 2 Current Skew - - (between channels) Output Current vs. Output Voltage Regulation Output Current vs. Supply Voltage Regulation %/dVDS VDS within 1.0V and 3.0V - ±0.1 - %/V %/dVDD VDD within 3.2V and 3.6V - ±1 - %/V Pull-up Resistance RIN(up) OE/SW/ED 250 500 800 KΩ 250 500 800 KΩ Pull-down Resistance Threshold Current for Error Detection RIN(down) LE/MOD/CA Iout, Th1 Rext=744 Ω, CG= 0.992, Iout, target = 25mA - - 24.9 mA Iout, Th2 Rext=372 Ω, CG= 0.992, Iout, target = 50mA - - 40 mA CG= 0.992 - 0.87 - IDD(off) 0 Rext=Open, “OFF” Supply Current “ON” OUT0 ~ OUT7 =Off, IDD(off) 1 Rext=744 Ω, OUT0 ~ OUT7 =Off, CG= 0.992 - 3.7 - IDD(off) 2 Rext=372 Ω, OUT0 ~ OUT7 =Off, CG= 0.992 - 6.37 - IDD(on) 1 Rext=744 Ω, OUT0 ~ OUT7 =On, CG= 0.992 - 3.4 - IDD(on) 2 Rext=372 Ω, OUT0 ~ OUT7 =On, CG= 0.992 - 6.1 - - 13 - mA August 2004, VA.00 8-Bit Constant Current LED Driver with LED Error Detection and Run-Time Current Adjustment MBI5171 Switching Characteristics (VDD= 5.0V) Characteristics Min. Typ. Max. Unit tpLH1 - 100 150 ns tpLH2 - 100 150 ns tpLH3 - 100 150 ns CLK - SDO tpLH 20 25 30 ns CLK - OUTn tpHL1 - 100 150 ns - 100 150 ns - 100 150 ns 20 25 30 ns 20 - - ns 20 - - ns 200 - - ns 10 - - ns 5 - - ns CLK - OUTn Propagation Delay LE/MOD/CA - OUTn Time (“L” to “H”) OE/SW/ED - OUTn Propagation Delay LE/MOD/CA - OUTn Time (“H” to “L”) OE/SW/ED - OUTn Pulse Width Symbol Condition Test Circuit for Switching Characteristics tpHL2 tpHL3 CLK - SDO tpHL CLK tw(CLK) LE/MOD/CA tw(L) OE/SW/ED (@ Iout< 60mA) tw(OE) VDD=5.0 V VDS=0.8 V VIH=VDD VIL=GND Rext=372 Ω VL=4.0 V RL=64 Ω CL=10 pF CG= 0.992 Hold Time for LE/MOD/CA th(L) Setup Time for LE/MOD/CA tsu(L) Maximum CLK Rise Time tr* - - 500 ns Maximum CLK Fall Time tf* - - 500 ns Output Rise Time of Vout (turn off) tor - 120 150 ns Output Fall Time of Vout (turn on) tof - 200 250 ns Clock Frequency FCLK - - 25.0 MHz Cascade Operation * If MBI5171 are connected in cascade and tr or tf is large, it may be critical to achieve the timing required for data transfer between two cascaded LED drivers MBI5171. - 14 - August 2004, VA.00 8-Bit Constant Current LED Driver with LED Error Detection and Run-Time Current Adjustment MBI5171 Switching Characteristics (VDD= 3.3V) Characteristics Symbol Min. Typ. Max. Unit tpLH1 - 100 150 ns tpLH2 - 100 150 ns tpLH3 - 100 150 ns CLK - SDO tpLH 45 55 65 ns CLK - OUTn tpHL1 - 130 200 ns - 130 200 ns - 130 200 ns 45 55 65 ns 20 - - ns 20 - - ns 200 - - ns 10 - - ns 5 - - ns CLK - OUTn Propagation Delay LE/MOD/CA - OUTn Time (“L” to “H”) OE/SW/ED - OUTn Pulse Width Test Circuit for Switching Characteristics tpHL2 Propagation Delay LE/MOD/CA - OUTn Time (“H” to “L”) OE/SW/ED - OUTn Condition tpHL3 CLK - SDO tpHL CLK tw(CLK) LE/MOD/CA tw(L) OE/SW/ED (@ Iout< 60mA) tw(OE) VDD=3.3 V VDS=0.8 V VIH=VDD VIL=GND Rext=372 Ω VL=4.0 V RL=64 Ω CL=10 pF CG= 0.992 Hold Time for LE/MOD/CA th(L) Setup Time for LE/MOD/CA tsu(L) Maximum CLK Rise Time tr - - 500 ns Maximum CLK Fall Time tf - - 500 ns Output Rise Time of Vout (turn off) tor - 120 150 ns Output Fall Time of Vout (turn on) tof - 200 400 ns - - 12.0 MHz Clock Frequency Cascade Operation FCLK Test Circuit for Electrical Characteristics Test Circuit for Switching Characteristics IDD IDD VDD OE /SW IIH,IIL CLK LE/MOD/CA IOUT IOUT VIH, VIL .. .. OUT0 OUT7 VDD OE /SW Function CLK Generator LE/MOD/CA .. . OUT0 OUT7 RL SDI SDI R - EXT GND SDO R - EXT GND VIH, VIL SDO CL Logic Input Waveform Iref VIH = VDD VL Iref CL VIL = GND tr = tf = 10 ns - 15 - August 2004, VA.00 8-Bit Constant Current LED Driver with LED Error Detection and Run-Time Current Adjustment MBI5171 Timing Waveform Normal Mode tW(CLK) tsu(D) SDI 50% 50% CLK 50% 50% th(D) 50% SDO tW(L) tpLH, tpHL LE/MOD/CA 50% 50% th(L) OE/SW/ ED tsu(L) LOW = OUTPUT ENABLED HIGH = OUTPUT OFF 50% OUTn LOW = OUTPUT ON tpLH1, tpHL1 tpLH2, tpHL2 tW(OE) OE/SW/ ED 50% 50% tpLH3 tpHL3 90% 50% 10% OUTn tof - 16 - 90% 50% 10% tor August 2004, VA.00 8-Bit Constant Current LED Driver with LED Error Detection and Run-Time Current Adjustment MBI5171 Switching to Special Mode tW(CLK) CLK 50% 50% 50% tsu(MOD) th(MOD) LE/MOD/CA 50% 50% 2 CLK tsu(SW) OE/SW/ ED th(SW) 50% 50% tW(SW) Reading Error Status Code CLK 50% 50% th(SW) 50% 50% 50% tsu(SW) th(SW) tsu(SW) tsu(ER) OE/SW/ ED 50% 50% tw(ED) - 17 - August 2004, VA.00 8-Bit Constant Current LED Driver with LED Error Detection and Run-Time Current Adjustment MBI5171 Operation Principle Constant Current In LED display applications, MBI5171 provides nearly no current variations from channel to channel and from IC to IC. This can be achieved by: 1) While IOUT ≦ 100mA, the maximum current skew between channels is less than ±3% and that between ICs is less than ±6%. 2) In addition, the characteristics curve of output stage in the saturation region is flat as the figure shown below. Thus, the output current can be kept constant regardless of the variations of LED forward voltages (Vf). The output current in the saturation region is so flat that we define it as target current Iout, target. Iout v.s. VDS Curve for Various Rext 140 120 Iout (mA) 100 80 60 40 20 0 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 VDS (V) - 18 - August 2004, VA.00 8-Bit Constant Current LED Driver with LED Error Detection and Run-Time Current Adjustment MBI5171 Adjusting Output Current MBI5171 scales up the reference current Iref set by the external resistor Rext to sink a current Iout at each output port. Users can follow the below formulas to calculate the target output current Iout, target in the saturation region: VR-EXT = 1.25Volt x VG Iref = VR-EXT / Rext if another end of the external resistor Rext is connected to ground. Iout, target = Iref x 15 x 3^(CM-1) where Rext is the resistance of the external resistor connected to the R-EXT terminal, and VR-EXT is the voltage of the R-EXT terminal and controlled by the programmable voltage gain VG, which is defined by the Configuration Code. The Current Multiplier CM would determine that the ratio Iout, target/Iref is 15 or 5. After power-on, the default value of VG is 127/128 = 0.992 and the default value of CM is 1, so that the ratio Iout, target/Iref is 15. Based on the default VG and CM, VR-EXT = 1.25Volt x 127/128= 1.24Volt Iout, target = (1.24Volt / Rext ) x 15 Hence, the default magnitude of current is around 50mA at 372Ω and 25mA at 744Ω. The default relationship after power-on between Iout, target and Rext is shown in the following figure. Default Relationship Curve Between I out, target and Rext After Power-On 140 120 Iout, target (mA) 100 VDS= 1.0V VDD= 5.0V CG= 0.992 80 60 40 20 0 0 500 1000 1500 2000 2500 3000 3500 4000 Rext (Ω) Operation Phases MBI5171 exploits the Share-I-O™ technique to extend the functionality of pins in MBI5168 in order to provide LED load error detection and run-time programmable LED driving current in the Special Mode phase as well as the original function of MBI5168 in the Normal Mode phase. In order to switch between the two modes, MBI5171 monitors the signal OE/SW/ ED . Once an one-clock-wide pulse of OE/SW/ ED appears, MBI5171 would enter the two-clock-period transition phase---the Mode Switching phase. After power-on, the default operation mode is the Normal Mode. - 19 - August 2004, VA.00 8-Bit Constant Current LED Driver with LED Error Detection and Run-Time Current Adjustment MBI5171 Operation Mode Switching Switching to the Special Mode 1 2 3 4 Switching to the Normal Mode 5 1 2 3 4 5 x x 0 x CLK CLK OE/SW/ ED LE/MOD/CA 1 0 1 x x OE/SW/ ED 1 0 1 x x x 1 x LE/MOD/CA x x x Voltage High Phase Voltage Low Normal Mode or Mode Special Special Mode Switching Mode Phase Normal Mode or Mode Normal Special Mode Switching Mode As shown in the above figures, once a one-clock-wide short pulse “101” of OE/SW/ ED appears, MBI5171 would th enter the Mode Switching phase. At the 4 rising edge of CLK, if LE/MOD/CA is sampled as “Voltage High”, MBI5171 would switch to the Special Mode; otherwise, it would switch to the Normal Mode. Worthwhile noticing, rd th the signal LE/MOD/CA between the 3 and the 5 rising edges of CLK can not latch any data. Its level is just used for determining which mode to switch. However, the short pulse of OE/SW/ ED can still enable the output ports. During the mode switching, the serial data can still be transferred through the pin SDI and shifted out from the pin SDO. Note: 1. The signal sequence for the mode switching could be frequently used for making sure under which mode MBI5171 is working. 2. The aforementioned “1” and “0” are sampled at the rising edge of CLK. The “X” means its level would not affect the result of mode switching mechanism. Normal Mode Phase MBI5171 in the Normal Mode phase has similar functionality to MBI5168. The serial data could be transferred into MBI5171 via the pin SDI, shifted in the Shift Register, and go out via the pin SDO. The LE/MOD/CA can latch the serial data in the Shift Register to the Output Latch. OE/SW/ ED would enable the output drivers to sink current. The only difference is mentioned in the last paragraph about monitoring short pulse OE/SW/ ED . The short pulse would trigger MBI5171 to switch the operation mode. However, as long as the signal LE/MOD/CA is not Voltage High in the Mode Switching phase, MBI5171 would still remain in the Normal Mode as if no mode switching occurs. - 20 - August 2004, VA.00 8-Bit Constant Current LED Driver with LED Error Detection and Run-Time Current Adjustment MBI5171 Special Mode Phase In the Special Mode, as long as OE/SW/ ED is not at the Voltage Low, the serial data can still be shifted to the Shift Register via the pin SDI and shifted out via the SDO pin, as in the Normal Mode. But there are two differences between the Special Mode and the Normal Mode. 1 2 n≧3 CLK At least 2 μs OE/SW/ ED 1 0 0 0 SDO 1 1 1 1 Error Status Code Bit15 Bit14 Bit13 Bit12 Bit11 Data Source of From pin SDI Shift Register From Error Detector From pin SDI Reading Error Status Code (in Special Mode) The first difference is that when the state of OE/SW/ ED is pulled down to Voltage Low, MBI5171 in the Special Mode would execute error detection and load error status codes into the Shift Register, as well as enabling output ports to sink current. The above figure shows the timing sequence for error detection. The shown “0” and “1” are sampled at the rising edge of each CLK. At least three “0” must be sampled at the Voltage Low signal OE/SW/ ED . Just after the 2 nd “0” is sampled, the data input source of the Shift Register would come from 8-bit parallel error status codes out of the circuit Error Detector, instead of serial data via the pin SDI. Normally, the error status codes rd will be correctly generated at least 2μs after the falling edge of OE/SW/ ED . The occurrence of the 3 or later “0” results in the event that MBI5171 saves the detected error status codes into the Shift Register. Thus, when OE/SW/ ED is at the Voltage Low state, the serial data cannot be shifted into MBI5171 via the pin SDI. But when the state of OE/SW/ ED is pulled up to Voltage High from Voltage Low, the data input source of the Shift Register would again come from the pin SDI. At the same time, the output ports are disabled and the error detection is completed. Then, the error status codes saved in the Shift Register could be shifted out via the pin SDO bit by bit along with CLK, as well as the new serial data can be shifted into MBI5171 via the pin SDI. The limitation is that in the Special Mode, it couldn’t be allowed to simultaneously transfer serial data and detect LED load error status. - 21 - August 2004, VA.00 8-Bit Constant Current LED Driver with LED Error Detection and Run-Time Current Adjustment MBI5171 Writing Configuration Code (in Special Mode) N=0 1 2 3 4 5 6 7 CLK LE/MOD/CA SDI 8-Bit Configuration Code Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 The second difference is that the active high signal LE/MOD/CA latches the serial data in the Shift Register to the Configuration Latch, instead of the Output Latch. The latched serial data is regarded as the Configuration Code. The code would be memorized until power off or the Configuration Latch is re-written. As shown above, the timing for writing the Configuration Code is the same as that in the Normal Mode for latching output channel data. As aforementioned descriptions, both of Configuration Code and Error Status Code are transferred in common 8-bit Shift Register. Users must pay attention to the sequence of error detection and current adjustment to avoid the Configuration Code being overwritten by Error Status Code. Open-Circuit Detection Principle Iout Knee Point Given Rext Iout, target MBI5171 Output Characteristics Curve Iout, Th Iout, effect Effective Output Point Loading Line VDS, effect VDS Vknee The principle of MBI5171 LED Open-Circuit Detection is based on the comparison between the effective current level Iout, effect of each output port and the threshold current Iout, Th corresponding to Iout, target. The cross point between the Loading Line and MBI5171 Output Characteristics Curve is called as effective output point (VDS, effect, Iout, effect). If LED fails, due to open circuit, the Loading Line and the effective output point would change. Then, MBI5171 would catch the error status. But if the port is disabled, the output current would be absolutely 0mA and MBI5171 could not distinguish the change of the Loading Line. Thus, to detect the status of LED correctly, the output ports must be enabled. The relationship between the detected Error Status code and the position of the effective output point is shown in the following table. - 22 - August 2004, VA.00 8-Bit Constant Current LED Driver with LED Error Detection and Run-Time Current Adjustment MBI5171 State of Output Port OFF ON Condition of Effective Output Point Detected Open-Circuit Error Status Code Meaning Iout, effect ＝ 0mA ＜＜ Iout, Th “0” - Iout, effect ＜ Iout, Th “0” Open Circuit Iout, effect ≧ Iout, Th “1” Normal Note： As Iout, target ≧ 25mA, the threshold current Iout, Th ＝ Iout, target x 0.6 +10mA As Iout, target ＜ 25mA, the threshold current Iout, Th ＝ Iout, target Because the target current Iout, target in the saturation region set by the external resistor Rext and CG is a little bigger than the corresponding threshold current Iout, Th for error detection, system design engineers had better place the effective output point of normal LED load in the saturation region after the knee point, for instance, if they want to detect the LED open error. Then while LED is open, the effective output point would move to the origin, where Iout = 0mA. So, MBI5171 can distinguish and detect it and report an error status codes “0”. In fact, if LED’s are normal, the enabled ports would report error status codes “1” and the disabled would report “0”. The error status codes are the same as the content in the Output Latch. Short-Circuit Detection Principle Iout Given Rext Iout, effect1 = Iout, target MBI5171Output Characteristics Curve Iout, Th Loading Line with short error occurring Iout, effect2 Normal Loading Line VDS, effect2 Vknee VDS, effect1 VLED (insufficiently biasing) VDS When LED is damaged, a short-circuit error may occur. To effectively detect the short-circuit error, LEDs need insufficient biasing. The principle of MBI5171 LED Short Circuit Detection is based on the fact that the LED loading status is judged by comparing the effective current value(Iout, effect) of each output port with the threshold current(Iout, Th). When normal LED is insufficiently biased, its effective output point would be located at the segment Iout, effect < Iout, Th of MBI5171 Output Characteristics Curve, compared with LED with a short error falling within the segment Iout, effect > Iout, Th . The relationship between the Error Status code and the effective output point is shown below: State of Output Port OFF ON Condition of Effective Output Point Iout, effect = 0 Iout, effect < Iout, Th Iout, effect ≧ Iout, Th - 23 - Detected Short-Circuit Error Status Code “0” “0” “1” Meaning Normal Short Circuit August 2004, VA.00 8-Bit Constant Current LED Driver with LED Error Detection and Run-Time Current Adjustment MBI5171 8-Bit Configuration Code and Current Gain CG Bit Definition of 8-Bit Configuration Code Bit 0 Bit 1 Bit 2 Bit 3 Bit 4 Bit 5 Bit 6 Bit 7 Meaning CM HC CC0 CC1 CC2 CC3 CC4 CC5 Default Value 1 1 1 1 1 1 1 1 Bit definition of the Configuration Code in the Configuration Latch is shown above. Bit 7 is first sent into MBI5171 via the pin SDI. Bit 1 ~ 7, {HC, CC[0:5]}, would determine the voltage gain (VG), that affects the voltage at R-EXT terminal and indirectly the reference current Iref flowing through the external resistor at terminal R-EXT. Bit 0 is the Current Multiplier (CM) bit, that determines the ratio Iout, target/Iref. Each combination of VG and CM would give a Current Gain (CG). l VG: the relationship between {HC,CC[0:5]} and the Voltage Gain VG can be formulated as below: VG = (1 + HC) x (1 + D/64) / 4 5 4 3 2 1 0 D = CC0 x 2 + CC1 x 2 + CC2 x 2 + CC3 x 2 + CC4 x 2 + CC5 x 2 where HC is 1 or 0, and D is the binary value of CC[0:5]. So, the VG could be regarded as a floating-point number with one bit exponent HC and 6-bit mantissa CC[0:5]. {HC,CC[0:5]} divides the programmable voltage gain VG into 128 steps and two sub-bands: Low voltage sub-band (HC=0): VG = 1/4 ~ 127/256, linearly divided into 64 steps; High voltage sub-band (HC=1): VG = 1/2 ~ 127/128, linearly divided into 64 steps, too. l CM: as well as determining the ratio Iout, target/Iref, the CM bit would limit the output current range. High Current Multiplier (CM=1): Iout, target/Iref = 15 and suitable for output current range Iout = 10 ~ 120mA. Low Current Multiplier (CM=0): Iout, target/Iref = 5 and suitable for output current range Iout = 5 ~ 40mA. l CG: the total Current Gain is defined as the following. VR-EXT = 1.25Volt * VG Iref = VR-EXT / Rext if another end of the external resistor Rext is connected to ground. Iout, target = Iref * 15 * 3^(CM-1) = 1.25Volt / Rext * VG * 15 * 3^(CM-1) = (1.25Volt / Rext * 15) * CG We define CG = VG * 3^(CM-1). Hence CG = (1/12) ~ (127/128) and it is divided into 256 steps, totally. If CG = 127/128 = 0.992, the Iout, target-Rext relationship is similar to that in MBI5168. For example, a) When the Configuration Code {CM, HC, CC[0:5]} = {1,1,111111}, VG = 127/128 = 0.992; and CG = VG * 3^0 = VG = 0.992 b) When the Configuration Code is {1,1,000000}, VG = (1+0)*(1+0/64)/4 = 1/2 = 0.5; and CG = 0.5 c) When the Configuration Code is {0,0,000000}, VG = (1+0)*(1+ 0/64)/4 = 1/4; and CG = (1/4)*3^-1 = 1/12 After power on, the default value of the Configuration Code {CM, HC, CC[0:5]} is {1,1,111111}. Thus, VG = CG = 0.992. The relationship between the Configuration Code and the Current Gain CG is shown in the following. - 24 - August 2004, VA.00 8-Bit Constant Current LED Driver with LED Error Detection and Run-Time Current Adjustment MBI5171 1.00 0.95 0.90 0.85 0.80 0.75 0.70 0.65 0.60 0.55 0.50 0.45 0.40 0.35 0.30 0.25 0.20 0.15 0.10 0.05 0.00 CM =0 (Low Current Multiplier) HC = 0 (Low Voltage SubBand) HC = 1 (High Voltage SubBand) HC = 0 (Low Voltage SubBand) HC = 1 (High Voltage SubBand) {1,1,110000} {1,1,100000} {1,1,010000} {1,1,000000} {1,0,110000} {1,0,100000} {1,0,010000} {1,0,000000} {0,1,110000} {0,1,100000} {0,1,010000} {0,1,000000} {0,0,110000} {0,0,100000} {0,0,010000} CM=1 (High Current Multiplier) {0,0,000000} Current Gain CG Current Gain CG v.s. Configuration Code in Binary Format Configuration Code {CM,HC,CC[0:5]} in Binary Format - 25 - August 2004, VA.00 8-Bit Constant Current LED Sink Driver with8-Bit Constant Current LED Sink Driver with LED Error Detection and Run-Time Current LED Adjustment Error Detection and Run-Time Current Adjustment MBI5171 Timing Chart for Current Adjustment N of MBI5171 are connected in cascade, i.e., SDO, k --> SDI, k+1. And, all MBI5171 are connected to the same signal bus CLK, LE/MOD/CA and OE /SW/ ED . SDO, 0 SDI, 0 MBI5171, 0 SDI, 1 SDO, 1 MBI5171, 1 SDO, N-1 SDO, 2 MBI5171, N-2 MBI5171, 2 MBI5171, N-1 CLK LE/MOD/CA OE /SW/ ED 1 2 3 4 5 1 N x 8 CLK Pulses (Note 1) 2 3 4 5 CLK SDI, 0 CC0 CC5 -CC4 -CC3 -CC2 CC1 -HC -CM CC5 CC4 CC3 CC2 CC1 CC0 CC HC --CM CC5 -CC4 -CC3 -CC2 -CC1 -CC0 -HC -CM - CC5 CC4 CC3 CC2 CC1 CC0 HC --CM Configuration Codes (Note 1) (Note2) For MBI5171, N- 1 For MBI5171, N-2 For MBI5171, 1 For MBI5171, 0 LE/MOD/CA OE /SW/ ED LE/MOD/CA Pulse (Note 3) Writing the Configuration Codes, Code k, k = 0… (N x 8 –1) A Entering the Current Adjust Mode B N x 8 CLK pulses are required to shift the 8-bit Configuration Codes needed by N of MBI5171. C Note 2: Voltage Gain VG = (1+ HC) x (1 + D/64)/4 D = CC0 x 25+ CC1 x 24 + CC2 x 23 + CC3 x 22 + CC4 x 21 + CC5 x 20 . Current Gain CG = VG * 3^(CM-1) - 26 - Note 3: The LE/MOD/CA pulse writes the Configuration Codes to each MBI5171. Resuming to the Normal Mode August 2004, VA.00 8-Bit Constant Current LED Sink Driver with 8-Bit Constant Current LED Sink Driver with LED Error Detection and Run-Time Current Adjustment LED Error Detection and Run-Time Current Adjustment MBI5171 Timing Chart for Detecting LED Error The connection of each MBI5171 is referred to “Timing Chart for Current Adjustment”, shown on P26. At least 3 CLK Pulses Required (Note 2) th(L) N x 8 CLK Pulses (Note 1) 1 2 3 4 5 1 N x 8 CLK Pulses (Note 3) 2 3 4 5 CLK Could NOT shift into the Shift Register SDI, 0 N-1 N x 8 -1 LE/MOD/CA 2 Serial Data (Note 1) 1 0 Could shift into the Shift Registers T1 = 2 CLK T2 = 2µs LE/MOD/CA T3 (Note 2) OE/SW/ ED OE/SW/ ED SDO, 0 N-1 SDO, 1 7 6 15 14 2 1 0 Detected Error Status Codes N x 8 -2 A B Sending the serial image data (or test pattern data) serial data k, k = 0… (N x 8 –1) Note 1: N x 8 CLK pulses are required to shift the serial image data N x 8 bits needed by N of MBI5171. Switching to the Special Mode C SDO, N-1 N-1 Detecting the Error Status N x 8 -1 D Reading Back the Error Status Codes Note 2: T1 = 2 CLK pluses are required to change input of Shift Register. And, when Short-Circuit Detection is executed, LEDs should be insufficiently biased during this period. T2 = 2 μs is required to obtain the stable error status result. T3 = the third CLK pulses is required before OE/SW/ ED goes Voltage High. The rising edge of CLK writes the error status codes back to the MBI5171 built-in Shift Register. - 27 - Resuming to the Normal Mode Note 3: The rising edge of CLK after the rising edge of OE/SW/ ED would shift the new serial image data and error codes. An LED error will be represented by a “0”, to overwrite the original image data “1”. Image Data k, k = 0… (N x 8 –1), = all “1” is suggested. N x 8 CLK pulses shift all N x 8 error results (Error Status Code) via Node SDO, N-1. August 2004, VA.00 8-Bit Constant Current LED Sink Driver with LED Error Detection and Run-Time Current Adjustment MBI5171 Application Information Package Power Dissipation (PD) The maximum allowable package power dissipation is determined as PD(max) = (Tj – Ta) / Rth(j-a). When 8 output channels are turned on simultaneously, the actual package power dissipation is PD(act) = (IDD x VDD) + (IOUT x Duty x VDS x 8) Therefore, to keep PD(act) ≤ PD(max), the allowable maximum output current as a function of duty cycle is IOUT = { [ (Tj – Ta) / Rth(j-a) ] – (IDD x VDD) } / VDS / Duty / 8 where Tj = 150°C. Iout vs. Duty Cycle at Rth = 85.82 ( °C/W) 120 110 110 100 100 90 90 80 80 70 70 Iout (mA) 60 50 60 50 40 40 30 30 20 20 10 75% 80% 85% 90% 95% 100% 80% 85% 90% 95% 100% 70% 65% 60% 55% CD Device Type Iout vs. Duty Cycle at Rth = 94.91 ( °C/W) Iout vs. Duty Cycle at Rth = 61.63 ( °C/W) 120 120 110 110 100 100 90 90 80 80 70 Iout (mA) 60 50 40 70 60 50 40 30 30 20 20 10 Duty Cycle 70% 65% 60% 55% 50% 45% 40% 35% 30% 25% 20% 15% 5% 0 100% 95% 90% 85% 80% 75% 70% 65% 60% 55% 50% 45% 40% 35% 30% 25% 20% 15% 5% 10% 10 10% Iout (mA) 50% Duty Cycle CN Device Type 0 75% Duty Cycle 45% 40% 35% 30% 25% 20% 15% 5% 95% 0 100% 90% 85% 80% 75% 70% 65% 60% 55% 50% 45% 40% 35% 30% 25% 20% 15% 5% 10 10% 0 10% Iout (mA) Iout vs. Duty Cycle at Rth = 61.65 (°C/W) 120 Duty Cycle CP Device Type CDW Device Type Condition：VDS = 1.0V, VDD= 5.0V, 8 output channels active, Ta is listed in the legend below. Device Type Rth(j-a)(°C/W) CN 61.65 CD 85.82 CDW 61.63 CP 94.91 Note 25℃ 55℃ 85℃ - 28 - August 2004, VA.00 8-Bit Constant Current LED Sink Driver with LED Error Detection and Run-Time Current Adjustment MBI5171 Load Supply Voltage (VLED) Considering the package power dissipating limits, users had better operate MBI5171 within VDS = 0.4V~ 1.0V. If VLED is higher, for instance, than 5V, VDS may be so high that PD(act) > PD(max) , where VDS = VLED – Vf. In this case, it is recommended to use as low supply voltage as possible or to arrange a voltage reducer, VDROP. The voltage reducer lets VDS = (VLED – Vf) – VDROP. Resistors or Zener diodes can be used as the reducers in the applications as shown in the following figures. VLED VLED VDROP VDROP Vf Vf VDS VDS MBI5171 MBI5171 - 29 - August 2004, VA.00 MBI5171 8-Bit Constant Current LED Sink Driver with LED Error Detection and Run-Time Current Adjustment Outline Drawings MBI5171CN Outline Drawing MBI5171CD Outline Drawing - 30 - August 2004, VA.00 8-Bit Constant Current LED Sink Driver with LED Error Detection and Run-Time Current Adjustment MBI5171 MBI5171CDW Outline Drawing MBI5171CP Outline Drawing MBI5171 Package Information Device Type Package Type Weight(g) CN P-DIP16-300-2.54 1.02 CD SOP16-150-1.27 0.13 CDW SOP16-300-1.27 0.37 CP SSOP16-150-0.64 0.07 Note: The unit for the outline drawings is mm. - 31 - August 2004, VA.00