IS31FL3236 36 CHANNELS LED DRIVER July 2012 GENERAL DESCRIPTION FEATURES IS31FL3236 is comprised of 36 constant current channels each with independent PWM control, designed for driving LEDs. The output current of each channel can be set at up to 38mA (Max.) by an external resistor and independently scaled by a factor of 1, 1/2, 1/3 and 1/4. The average LED current of each channel can be changed in 256 steps by changing the PWM duty cycle through an I2C interface. The chip can be turned off by pulling the SDB pin low or by using the software shutdown feature to reduce power consumption. IS31FL3236 is available in QFN-44 (5mm × 5mm) and TQFP-48 package. It operates from 2.7V to 5.5V over the temperature range of -40°C to +85°C. APPLICATIONS 2.7V to 5.5V supply I2C interface, automatic address increment function Internal reset register Modulate LED brightness with 256 steps PWM Each channel can be controlled independently Each channel can be scaled independently by 1, 1/2, 1/3 and 1/4 -40°C to +85°C temperature range QFN-44 (5mm × 5mm) and TQFP-48 package Mobile phones and other hand-held devices for LED display LED in home appliances TYPICAL APPLICATION CIRCUIT Figure 1 Typical Application Circuit Note: The maximum global output current is set up to 23mA when REXT = 3.3kΩ. The maximum global output current can be set by external resistor, REXT. Please refer to the detail information in Page 11. Note: The IC should be placed far away from the mobile antenna in order to prevent the EMI. Integrated Silicon Solution, Inc. – www.issi.com Rev.B, 07/16/2012 1 IS31FL3236 PIN CONFIGURATION Package Pin Configuration (Top View) QFN-44 OUT3 1 36 OUT34 OUT4 2 35 OUT33 OUT5 3 34 OUT32 GND 4 TQFP-48 33 GND OUT6 5 32 OUT31 OUT7 6 31 OUT30 OUT8 7 30 OUT29 OUT9 8 29 OUT28 OUT10 9 28 OUT27 OUT11 10 27 OUT26 OUT12 11 26 OUT25 OUT13 12 25 OUT24 Integrated Silicon Solution, Inc. – www.issi.com Rev.B, 07/16/2012 2 IS31FL3236 PIN DESCRIPTION No. Pin Description 1~3 OUT3 ~ OUT5 Output channel 3~5 for LEDs. 4~16 5~17 OUT6 ~ OUT18 Output channel 6~18 for LEDs. 17,39 4,18,19, 33,42,43 GND Ground. 18~30 20~32 OUT19 ~ OUT31 Output channel 19~31 for LEDs. 31~35 34~38 OUT32 ~ OUT36 Output channel 32~36 for LEDs. 36 39 SDB Shutdown the chip when pulled low. 37 40 AD I2C address setting. 38 41 VCC Power supply. 40 44 R_EXT Input terminal used to connect an external resistor. This regulates the global output current. 41 45 SDA I2C serial data. 42 46 SCL I2C serial clock. 43,44 47,48 OUT1, OUT2 Output channel 1, 2 for LEDs. Thermal Pad Connect to GND. QFN TQFP 1~3 Integrated Silicon Solution, Inc. – www.issi.com Rev.B, 07/16/2012 3 IS31FL3236 ORDERING INFORMATION Industrial Range: -40°C to +85°C Order Part No. Package QTY IS31FL3236-QFLS2-TR QFN-44, Lead-free 2500/Reel IS31FL3236-TQLS2 TQFP-48, Lead-free 250/Tray Copyright © 2012 Integrated Silicon Solution, Inc. All rights reserved. ISSI reserves the right to make changes to this specification and its products at any time without notice. ISSI assumes no liability arising out of the application or use of any information, products or services described herein. Customers are advised to obtain the latest version of this device specification before relying on any published information and before placing orders for products. Integrated Silicon Solution, Inc. does not recommend the use of any of its products in life support applications where the failure or malfunction of the product can reasonably be expected to cause failure of the life support system or to significantly affect its safety or effectiveness. Products are not authorized for use in such applications unless Integrated Silicon Solution, Inc. receives written assurance to its satisfaction, that: a.) the risk of injury or damage has been minimized; b.) the user assume all such risks; and c.) potential liability of Integrated Silicon Solution, Inc is adequately protected under the circumstances Integrated Silicon Solution, Inc. – www.issi.com Rev.B, 07/16/2012 4 IS31FL3236 ABSOLUTE MAXIMUM RATINGS Supply voltage, VCC Voltage at SCL, SDA, SDB Voltage at OUT1 to OUT36 GND thermal current Maximum junction temperature, TJMAX Storage temperature range, TSTG Operating temperature range, TA -0.3V ~ +6.0V -0.3V ~ VCC+0.3V +5V 500mA 150°C -65°C ~ +150°C −40°C ~ +85°C Note: Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only and functional operation of the device at these or any other condition beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS Typical values are TA = 25°C, VCC = 3.6V. Symbol Parameter Condition Min. Typ. Unit 5.5 V VCC Supply voltage IMAX Maximum global output current VCC = 4.2V, VOUT = 0.8V REXT = 2kΩ, SL = “00” (Note 1) 38 mA IOUT Output current VOUT = 0.6V REXT = 3.3kΩ, SL = “00” 23 mA ICC Quiescent power supply current REXT = 3.3kΩ 9 mA ISD Shutdown current VSDB = 0V or software shutdown TA = 25°C, VCC = 3.6V IOZ Output leakage current VSDB = 0V or software shutdown, VOUT = 5.5V VEXT 2.7 Max. 2 Output voltage of R-EXT pin 3 5 μA 0.2 μA 1.3 V Logic Electrical Characteristics (SDA, SCL, SDB) VIL Logic “0” input voltage VCC = 2.7V VIH Logic “1” input voltage VCC = 5.5V IIL Logic “0” input current VINPUT = 0V (Note 2) IIH Logic “1” input current VINPUT = VCC (Note 2) Integrated Silicon Solution, Inc. – www.issi.com Rev.B, 07/16/2012 0.4 1.4 V V 5 5 nA nA 5 IS31FL3236 DIGITAL INPUT SWITCHING CHARACTERISTICS (Note 2) Symbol Parameter Condition Min. Typ. Max. Unit 400 kHz fSCL Serial-Clock frequency tBUF Bus free time between a STOP and a START condition 1.3 μs tHD, STA Hold time (repeated) START condition 0.6 μs tSU, STA Repeated START condition setup time 0.6 μs tSU, STO STOP condition setup time 0.6 μs tHD, DAT Data hold time tSU, DAT Data setup time 100 ns tLOW SCL clock low period 1.3 μs tHIGH SCL clock high period 0.7 μs 0.9 μs tR Rise time of both SDA and SCL signals, receiving (Note 3) 20+0.1Cb 300 ns tF Fall time of both SDA and SCL signals, receiving (Note 3) 20+0.1Cb 300 ns Note 1: The recommended minimum value of REXT is 2kΩ, or it may cause a large current. Note 2: Guaranteed by design. Note 3: Cb = total capacitance of one bus line in pF. ISINK ≤ 6mA. tR and tF measured between 0.3 × VCC and 0.7 × VCC. Integrated Silicon Solution, Inc. – www.issi.com Rev.B, 07/16/2012 6 IS31FL3236 DETAILED DESCRIPTION The 8-bit chip address is sent next, most significant bit first. Each address bit must be stable while the SCL level is high. I2C INTERFACE The IS31FL3236 uses a serial bus, which conforms to the I2C protocol, to control the chip’s functions with two wires: SCL and SDA. The IS31FL3236 has a 7-bit slave address (A7:A1), followed by the R/W bit, A0. Since IS31FL3236 only supports write operations, A0 must always be “0”. The value of bits A1 and A2 are decided by the connection of the AD pin. After the last bit of the chip address is sent, the master checks for the IS31FL3236’s acknowledge. The master releases the SDA line high (through a pull-up resistor). Then the master sends an SCL pulse. If the IS31FL3236 has received the address correctly, then it holds the SDA line low during the SCL pulse. If the SDA line is not low, then the master should send a “STOP” signal (discussed later) and abort the transfer. The complete slave address is: Table 1 Slave Address (Write only): Bit A7:A3 A2:A1 A0 Value 01111 AD 0 Following acknowledge of IS31FL3236, the register address byte is sent, most significant bit first. IS31FL3236 must generate another acknowledge indicating that the register address has been received. AD connected to GND, AD = 00; AD connected to VCC, AD = 11; AD connected to SCL, AD = 01; AD connected to SDA, AD = 10; Then 8-bit of data byte are sent next, most significant bit first. Each data bit should be valid while the SCL level is stable high. After the data byte is sent, the IS31FL3236 must generate another acknowledge to indicate that the data was received. The SCL line is uni-directional. The SDA line is bi-directional (open-collector) with a pull-up resistor (typically 4.7kΩ). The maximum clock frequency specified by the I2C standard is 400kHz. In this discussion, the master is the microcontroller and the slave is the IS31FL3236. The “STOP” signal ends the transfer. To signal “STOP”, the SDA signal goes high while the SCL signal is high. ADDRESS AUTO INCREMENT To write multiple bytes of data into IS31FL3236, load the address of the data register that the first data byte is intended for. During the IS31FL3236 acknowledge of receiving the data byte, the internal address pointer will increment by one. The next data byte sent to IS31FL3236 will be placed in the new address, and so on. The auto increment of the address will continue as long as data continues to be written to IS31FL3236 (Figure 5). The timing diagram for the I2C is shown in Figure 2. The SDA is latched in on the stable high level of the SCL. When there is no interface activity, the SDA line should be held high. The “START” signal is generated by lowering the SDA signal while the SCL signal is high. The start signal will alert all devices attached to the I2C bus to check the incoming address against their own chip address. Figure 2 Interface timing Figure 3 Integrated Silicon Solution, Inc. – www.issi.com Rev.B, 07/16/2012 Bit transfer 7 IS31FL3236 Figure 4 Writing to IS31FL3236(Typical) Figure 5 Writing to IS31FL3236(Automatic address increment) REGISTERS DEFINITIONS Table 2 Register Function Address 00h Name Function Table Shutdown Register Set software shutdown mode 3 PWM Register 36 channels PWM duty cycle data register 4 Update Register Load PWM Register and LED Control Register’s data - LED Control Register Channel 1 to 36 enable bit and current setting 5 4Ah Global Control Register Set all channels enable 6 4Fh Reset Register Reset all registers into default value - 01h~24h 25h 26h~49h Table 3 Table 4 01h~24h 00h Shutdown Register D7:D1 D0 Bit D7:D0 Name - SSD Name PWM Default 0000000 0 Default 0000 0000 SSD 0 1 Software Shutdown Enable Software shutdown mode Normal operation 0000 0000 xxxx xxxx 0000 0000 xxxx xxxx PWM Register(OUT1~OUT36) Bit The Shutdown Register sets software shutdown mode of IS31FL3236. Default The PWM Registers adjusts LED luminous intensity in 256 steps. The value of a channel’s PWM Register decides the average output current for each output, OUT1~OUT36. The average output current may be computed using the Formula (1): I PWM I OUT 7 D[n] 2 n 256 n0 (1) Where “n” indicates the bit location in the respective PWM register. Integrated Silicon Solution, Inc. – www.issi.com Rev.B, 07/16/2012 8 IS31FL3236 For example: D7:D0 = 10110101, IOUT = IMAX (20+22+24+25+27)/256 The IOUT of each channel is setting by the SL bit of LED Control Register (26h~49h). Please refer to the detail information in Page 11. 25h PWM Update Register The data sent to the PWM Registers and the LED Control Registers will be stored in temporary registers. A write operation of any 8-bit value to the Update Register is required to update the registers (01h~24h, 26h~49h). Table 5 26h~49h LED Control Register (OUT1~OUT36) Bit D7:D3 D2:D1 D0 Name - SL OUT Default 00000 00 0 Table 6 4Ah Global Control Register Bit D7:D1 D0 Name - G_EN Default 0000000 0 The Global Control Register set all channels enable. G_EN 0 1 Global LED Enable Normal operation Shutdown all LEDs 4Fh Reset Register Once user writes any 8-bit data to the Reset Register, IS31FL3236 will reset all registers to default value. On initial power-up, the IS31FL3236 registers are reset to their default values for a blank display. The LED Control Registers store the on or off state of each LED and set the output current. SL 00 01 10 11 Output Current Setting (IOUT) IMAX IMAX/2 IMAX/3 IMAX/4 OUT 0 1 LED State LED off LED on Integrated Silicon Solution, Inc. – www.issi.com Rev.B, 07/16/2012 9 IS31FL3236 FUNCTIONAL BLOCK DIAGRAM VCC Scaling Data SDA SCL I2C Interface Registers EN Data PWM&EN &Scaling Logic PWM Data CMP OSC Counter Bias Output OUT1~OUT36 GND Integrated Silicon Solution, Inc. – www.issi.com Rev.B, 07/16/2012 10 IS31FL3236 TYPICAL APPLICATION PWM CONTROL Table 7 32 gamma steps with 256 PWM steps The PWM Registers (01h~24h) can modulate LED brightness of 36 channels with 256 steps. For example, if the data in PWM Register is “0000 0100”, then the PWM is the fourth step. C(0) C(1) C(2) C(3) C(4) C(5) C(6) C(7) 0 1 2 4 6 10 13 18 C(8) C(9) C(10) C(11) C(12) C(13) C(14) C(15) 22 28 33 39 46 53 61 69 Writing new data continuously to the registers can modulate the brightness of the LEDs to achieve a breathing effect. C(16) C(17) C(18) C(19) C(20) C(21) C(22) C(23) REXT 78 86 96 106 116 126 138 149 C(24) C(25) C(26) C(27) C(28) C(29) C(30) C(31) 161 173 186 199 212 226 240 255 The maximum output current of OUT1~OUT36 can be adjusted by the external resistor, REXT, as described in Formula (2). 256 224 192 (2) PWM Data I MAX V x EXT REXT x = 58.5, VOUT = 0.8V, VEXT = 1.3V. 160 128 96 The recommended minimum value of REXT is 2kΩ. 64 CURRENT SETTING 32 The current of each LED can be set independently by the SL bit of LED Control Register (26h~49h). The maximum global current is set by the external register REXT. When channels drive different quantity of LEDs, adjust maximum output current according to quantity of LEDs to ensure average current of each LED is the same. For example, set REXT = 3.3kΩ then IMAX = 23mA. If OUT1 drives two LEDs and OUT2 drives four LEDs, set the SL bit of LED Control Register (26h) to “01” and SL bit of LED Control Register (27h) to “00”. So the current of OUT1 is IOUT1 = IMAX/2 = 11.5mA and the current of OUT2 is IOUT2 = IMAX = 23mA. The average current of each LED is the same. GAMMA CORRECTION In order to perform a better visual LED breathing effect we recommend using a gamma corrected PWM value to set the LED intensity. This results in a reduced number of steps for the LED intensity setting, but causes the change in intensity to appear more linear to the human eye. Gamma correction, also known as gamma compression or encoding, is used to encode linear luminance to match the non-linear characteristics of display. Since the IS31FL3236 can modulate the brightness of the LEDs with 256 steps, a gamma correction function can be applied when computing each subsequent LED intensity setting such that the changes in brightness matches the human eye's brightness curve. Integrated Silicon Solution, Inc. – www.issi.com Rev.B, 07/16/2012 0 0 4 8 12 16 20 24 28 32 Intensity Steps Figure 6 Gamma Correction(32 Steps) Choosing more gamma steps provides for a more continuous looking breathing effect. This is useful for very long breathing cycles. The recommended configuration is defined by the breath cycle T. When T=1s, choose 32 gamma steps, when T=2s, choose 64 gamma steps. The user must decide the final number of gamma steps not only by the LED itself, but also based on the visual performance of the finished product. Table 8 64 gamma steps with 256 PWM steps C(0) C(1) C(2) C(3) C(4) C(5) C(6) C(7) 0 1 2 3 4 5 6 7 C(8) C(9) C(10) C(11) C(12) C(13) C(14) C(15) 8 10 12 14 16 18 20 22 C(16) C(17) C(18) C(19) C(20) C(21) C(22) C(23) 24 26 29 32 35 38 41 44 C(24) C(25) C(26) C(27) C(28) C(29) C(30) C(31) 47 50 53 57 61 65 69 73 C(32) C(33) C(34) C(35) C(36) C(37) C(38) C(39) 77 81 85 89 94 99 104 109 C(40) C(41) C(42) C(43) C(44) C(45) C(46) C(47) 114 119 124 129 134 140 146 152 C(48) C(49) C(50) C(51) C(52) C(53) C(54) C(55) 158 164 170 176 182 188 195 202 C(56) C(57) C(58) C(59) C(60) C(61) C(62) C(63) 209 216 223 230 237 244 251 255 11 IS31FL3236 256 SHUTDOWN MODE 224 Shutdown mode can be used as a means of reducing power consumption. During shutdown mode all registers retain their data. PWM Data 192 160 SOFTWARE SHUTDOWN 128 By setting SSD bit of the Shutdown Register (00h) to “0”, the IS31FL3236 will operate in software shutdown mode. When the IS31FL3236 is in software shutdown mode, all current sources are switched off. 96 64 32 0 0 HARDWARE SHUTDOWN 8 16 24 32 40 48 56 64 Intensity Steps Figure 7 Gamma Correction(64 Steps) The chip enters hardware shutdown mode when the SDB pin is pulled low. Note, the data of 32 gamma steps is the standard value and the data of 64 gamma steps is the recommended value. Integrated Silicon Solution, Inc. – www.issi.com Rev.B, 07/16/2012 12 IS31FL3236 CLASSIFICATION REFLOW PROFILES Profile Feature Pb-Free Assembly Preheat & Soak Temperature min (Tsmin) Temperature max (Tsmax) Time (Tsmin to Tsmax) (ts) 150°C 200°C 60-120 seconds Average ramp-up rate (Tsmax to Tp) 3°C/second max. Liquidous temperature (TL) Time at liquidous (tL) 217°C 60-150 seconds Peak package body temperature (Tp)* Max 260°C Time (tp)** within 5°C of the specified classification temperature (Tc) Max 30 seconds Average ramp-down rate (Tp to Tsmax) 6°C/second max. Time 25°C to peak temperature 8 minutes max. Figure 8 Classification profile Integrated Silicon Solution, Inc. – www.issi.com Rev.B, 07/16/2012 13 IS31FL3236 PACKAGE INFORMATION QFN-44 Note: All dimensions in millimeters unless otherwise stated. Integrated Silicon Solution, Inc. – www.issi.com Rev.B, 07/16/2012 14 IS31FL3236 TQFP-48 Integrated Silicon Solution, Inc. – www.issi.com Rev.B, 07/16/2012 15