8-Bit LED Driver CS8818 Revision History Rev. No. History Issue Date 1.0 New issue Sep. 30, 2008 1.1 Update AC data Dec. 29, 2008 Modify Rext vs. Iout relation 1.2 Modify Rext vs. Iout relation Oct. 8, 2009 1.3 Format modify Oct. 19, 2010 1 Chiplus reserves the right to change product or specification without notice. Rev. 1.3 8-Bit LED Driver CS8818 CS8818(CT/AD) 8-Bit Constant Current LED Driver with 3.0V to 5.5V Supply Voltage Description The CS8818 is an 8-Bit constant current LED driver IC which is designed for LED displays. The output current can be adjusted by using an external resistor. All outputs will have the same current drive level which is crucial in LED display application. This driver has built-in 8-bit constant current outputs, an 8-bit shift register, and an 8-bit latch circuit. These drivers have been designed by using CMOS process. Feature Output current capability: 70mA each output Constant current range: 5mA to 70mA For common anode LED application Power supply voltage range VDD=3.0V to 5.5V Maximum output drain voltage 7.0V Serial data transfer rate: 25MHz(Cascade Connection) Operating temperature range: -40 to 85 degree C Output current accuracy: Between Bits : < +-1.5 % Between ICs: < +-4 % Product Family CS8818CT ------- 16SOP(150mil, 1.27mm lead-pitch) CS8818AD ------- 16SSOP(150mil, 0.635mm lead-pitch) 2 Chiplus reserves the right to change product or specification without notice. Rev. 1.3 8-Bit LED Driver CS8818 Pin Assignment Block Diagram Truth Table CLOCK LATCH ENABLE SERIAL-IN OUT0---OUT3---OUT7 SERIAL-OUT Positive edge H L Dn /Dn---/Dn-3---/Dn-7 Dn-7 Positive edge L L Dn+1 No Change Dn-6 Positive edge H L Dn+2 /Dn+2---/Dn-1---/Dn-5 Dn-5 Negative edge X L Dn+3 /Dn+2---/Dn-1---/Dn-5 Dn-5 Negative edge X H Dn+3 Off Dn-5 3 Chiplus reserves the right to change product or specification without notice. Rev. 1.3 8-Bit LED Driver CS8818 Timing Diagram Note: 1. The latch circuit is a level-latch, not an edge-triggered latch. 2. The latch circuit holds data when LATCH pin low. When the LATCH pin is at high-level, the latch circuit passes the data from input to output. When ENABLE pin is at low-level, the latched data is transferred to the output pin OUT0~OUT7. When ENABLE pin is at high-level, the OUT0~OUT7 is turned off regardless of the latch data. 4 Chiplus reserves the right to change product or specification without notice. Rev. 1.3 8-Bit LED Driver CS8818 Pin Description Pin No. Pin Name Function 1 GND 2 SERIAL-IN 3 CLOCK Clock input terminal for shift register, rising edge trigger. 4 LATCH Data latch input pin. When LATCH=High-level, data is passed to GND Pin. Serial input data pin. OUT0~OUT7, when LATCH=Low-level, data is latched. 5~12 OUT0~OUT7 13 ENABLE 8 constant current output pins to drive common anode LEDs. Data output enable pin, when ENABLE=High-level, all OUT0~OUT7 are turned off, and when ENABLE=Low-level, all OUT0~OUT7 are enabled. 14 SERIAL-OUT 15 R-EXT 16 VDD Serial data output pin for cascade operation. The external resistor connection pin to adjust the output current. 3.0V~5.5V supply voltage pin. Equivalent Circuits of I/O Pins 5 Chiplus reserves the right to change product or specification without notice. Rev. 1.3 8-Bit LED Driver CS8818 Absolute Maximum Ratings Characteristics Symbol Supply Voltage Rating VDD Unit +7.0 V V Input Voltage Vin -0.4 to VDD+0.4 Output Current Iout +70 Output Voltage Vout -0.5 to 7.0 GND Pin Current IGND 560 mA Clock Frequency fCLK 25 MHz Power Dissipation Pd Thermal Resistance mA V CT: 0.86 AD: 0.79 CT: 110.9 AD: 115.4 Rth(j-a) W ℃/W Operating Temperature Top -40 to 85 ℃ Storage Temperature Tstg -55 to 150 ℃ Recommended Operating Condition Characteristics Symbol Min Typ Max Unit 3.0 5.0 5.5 V 7.0 V OUTn 70 mA IOL SERIAL-OUT Vol=0.5V 2.5 IOH SERIAL-OUT Voh=4.3V -2.0 Supply Voltage VDD Output Voltage VOUT Output Current IOUT Input Voltage Clock Frequency Condition VIH 0.7VDD VDD+0.3 VIL -0.3 0.3VDD fCLK VDD=5.0V, Cascade connection 25 VDD=3.0V, Cascade connection 20 V MHz Latch Pulse Width twLatch VDD=4.5V ~ 5.5V 15 ns Clock Pulse Width twCLOCK VDD=4.5V ~ 5.5V 15 ns Set-Up Time for Data tSETUP3 VDD=4.5V ~ 5.5V 20 ns Set-Up Time for Latch tSETUP2 VDD=4.5V ~ 5.5V 15 ns Set-Up Time for Clock tSETUP1 VDD=4.5V ~ 5.5V 20 ns tHOLD VDD=4.5V ~ 5.5V 20 ns Hold Time for Data 6 Chiplus reserves the right to change product or specification without notice. Rev. 1.3 8-Bit LED Driver CS8818 Electrical Characteristics (Temp=25℃) Characteristics Symbol Condition Min Typ Max Unit 3.0 5.0 5.5 V Supply Voltage VDD Output Current IOUT1 VOUT=1.0V, VDD=5.0V, 24.6 IOUT2 R-EXT=700Ohm 5.0 mA VOUT=1.0V, VDD=5.0V, R-EXT=3450Ohm Output Current Error IOUT1 VOUT=1.0V, R-EXT=700Ohm -1.5 +1.5 Between Bits IOUT2 VOUT=1.0V, R-EXT=3450Ohm -1.5 +1.5 Output Current Error ILO3 VOUT=1.0V, R-EXT=700Ohm -4 +4 Between Chips IOL4 VOUT=1.0V, R-EXT=3450Ohm -4 +4 Output Leakage ILEAK VOUT=5.0V % % 1 uA Current Input Voltage Low VIL VDD=5.0V 0 1.5 V Input Voltage High VIH VDD=5.0V 3.5 5.0 V Output Voltage SOUT VOL IOL=+1.5mA, VDD=5.0V 0.5 V VOH IOH=-1.5mA, VDD=5.0V ENABLE Pin 202 KOhm LATCH Pin 128 KOhm Pull-Up Resistor R(UP) Pull-Down Resistor R(DOWN) Supply Current(Off) IDD(Off) (OUT0~OUT7 Off) Supply Current(On) (OUT0~OUT7 On) IDD(On) 4.3 VDD=5.0V, R-EXT=700Ohm 3.7 VDD=5.0V, R-EXT=3450Ohm 0.9 VDD=5.0V, R-EXT=Open 0.2 VDD=5.0V, R-EXT=700Ohm 3.7 VDD=5.0V, R-EXT=3450Ohm 0.9 7 Chiplus reserves the right to change product or specification without notice. mA mA Rev. 1.3 8-Bit LED Driver CS8818 Switching Characteristics (Temp=25℃, VDD=5V, VIH=3.5V, VIL=0V, R-EXT=860Ohm) Characteristics Propagation Delay Pulse Width Symbol Condition Min Typ Max Unit tpLH1 CLK-OUTn, LATCH=“H”, ENABLE=“L” 40 60 ns tpLH2 LATCH-OUTn, ENABLE=“L” 35 50 ns tpLH3 ENABLE-OUTn, LATCH=“H” 20 30 ns tpLH CLK-SERIAL OUT 30 40 ns tpHL1 CLK-OUTn, LATCH=“H”, ENABLE=“L” 80 125 ns tpHL2 LATCH-OUTn, ENABLE=“L” 75 120 ns tpHL3 ENABLE-OUTn, LATCH=“H” 130 180 ns tpHL CLK-SERIAL OUT 30 40 ns tW(CLOCK) CLOCK 15 ns tW(LATCH) LATCH 10 ns ENABLE 180 ns tW(ENABLE) Output Rise Time tor Voltage waveform 10%~90% 30 75 150 ns Output Fall Time tof Voltage waveform 90%~10% 10 20 40 ns Max CLK Rise Time tr 480 ns Max CLK Fall Time tf 480 ns Test Circuit (RL=162Ohm, CL=10pf, VL=5.0V) 8 Chiplus reserves the right to change product or specification without notice. Rev. 1.3 8-Bit LED Driver CS8818 Timing Waveform 9 Chiplus reserves the right to change product or specification without notice. Rev. 1.3 8-Bit LED Driver CS8818 Output Current vs. R-EXT (VDD=5V) Iout = (1.22/Rext) x 14.62 CS8818 Rext vs. Iout Curve Iout (mA) 90 80 70 60 50 40 30 20 10 0 0 1000 2000 3000 4000 5000 6000 7000 Rext (ohm) CS8818 Vds vs. Iout Curve 80 Iout(mA) 70 60 50 40 30 20 10 1155ohm 691ohm 345ohm 247ohm 0 0 0.5 1 1.5 2 2.5 3 3.5 Vds 10 Chiplus reserves the right to change product or specification without notice. Rev. 1.3 8-Bit LED Driver CS8818 Typical Application LED supply voltage is set-up by following equation: VLED = VCE + Vf + Vo To prevent too much power dissipated by driver due to the higher VLED, an additional R can be introduced to reduce the Vo when output is consuming current. R = ( VLED – VCE – Vf – Vo min)/( Io max * Bit max) Order Information Part No. Package Type Lead Pitch CS8818CT 16SOP(150mil) 1.27mm CS8818AD 16SSOP(150mil) 0.635mm 11 Chiplus reserves the right to change product or specification without notice. Rev. 1.3 8-Bit LED Driver CS8818 12 Chiplus reserves the right to change product or specification without notice. Rev. 1.3 8-Bit LED Driver CS8818 13 Chiplus reserves the right to change product or specification without notice. Rev. 1.3