isl97635 Intersil Corporation, isl97635 Datasheet
isl97635
Available stocks
Related parts for isl97635
isl97635 Summary of contents
Page 1
... Data Sheet SMBus 8-Channel LED Driver The ISL97635 is a digitally controlled LED driver that controls 8 channels of LED current for LCD backlight applications. The ISL97635 is capable of driving typically 72 (8x9) pieces of 3.5V/30mA or 80 (8x10) pieces of 3.2V/20mA LEDs. The ISL97635’s 8 channels of voltage controlled current sources with typical currents matching of ± ...
Page 2
... Typical Application Circuit VBL 24V 2 ISL97635 V = 34.5V, 30mA PER STRING OUT ISL97635 FAULT OVP 16 VIN 24 PGND VDC 17 PGND 18 22 IIN0 15 COMP SMBCLK 1 IIN1 14 SMBDAT 2 IIN2 13 PWMI/EN 6 IIN3 12 PWMO 4 IIN4 10 11 IIN5 9 RSET IIN6 8 3 FPWM IIN7 7 5 GND FN6434.2 ...
Page 3
... DETECT GENERATOR + + - - REGISTERS + + PWM BRIGHTNESS CONTROL - - DEVICE CONTROL PWM/OC/SC FAULT/STATUS IDENTIFICATION AM DC BRIGHTNESS CONTROL CONFIGURATION FIGURE 1. ISL97635 BLOCK DIAGRAM 34.5V, 30mA PER STRING (8x9 = 72 WHITE LEDS OVP PGND IIN0 IIN0 OC, SC DETECT IIN7 OC, SC DETECT FAULT/STATUS REGISTER TEMP SENSOR FAULT/STATUS REGISTER FN6434 ...
Page 4
... SWILimit Boost FET Current Limit r Internal Boost Switch ON-Resistance DS(ON) 4 ISL97635 Thermal Information Thermal Resistance (Typical, Notes 1, 2) θ QFN . . . . . . . . . . . . . . . . . . . . . . Thermal Characterization (Typical, Note QFN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...
Page 5
... Hold Time After (Repeated) START Condition. After this HD:STA Period, the First Clock is Generated t Repeated Start Condition Setup Time SU:STA t Stop Condition Setup Time SU:STO 5 ISL97635 = -40°C to +85° DESCRIPTION V IN each 8.2µH with DCR 106mΩ, T VIN = 12V, 54 LEDs, 20mA each 8.2µH with DCR 106mΩ ...
Page 6
... RSET ILEDmax Maximum LED Current per Channel PWM GENERATOR FPWM Generated PWM Frequency DPWM Duty Cycle Of Generated PWM (DC-to-PWM) tMAX_PWM_OFF Maximum PWMI Off Time Before Shutdown 6 ISL97635 = -40°C to +85° DESCRIPTION Rising above VUVLO capacitor < 10µ VDC capacitor < ...
Page 7
... I (mA) O FIGURE 4. 3 EFFICIENCY 10µH WITH DCR = 500mΩ, 1mm 4µFx4.7µF/50V O 7 ISL97635 = -40°C to +85° DESCRIPTION VDC = 5. 9S8P - 18V 86 84 7S8P - 18V 9S6P - 18V 82 80 ...
Page 8
... V = 18V PWM DUTY CYCLE (%) FIGURE 8. PWM DIMMING LINEARITY FIGURE 10 50% PWM DIMMING L 8 ISL97635 (Continued) 1.0 0.9 0.8 0.7 0.6 0.5 0 FIGURE 7. CURRENT MATCHING vs DUTY CYCLE 100 FIGURE 9. LX, VIIN, IL AND I FIGURE 11 12V IN 1kHz ...
Page 9
... Typical Performance Curves FIGURE 12 50% PWM DIMMING FIGURE 14. RIPPLE VOLTAGE 9 ISL97635 (Continued) FIGURE 16. RIPPLE VOLTAGE ZOOM IN FIGURE 13. LX ZOOM IN AT 50% DIMMING FIGURE 15 50% PWM DIMMING LED December 22, 2008 FN6434.2 ...
Page 10
... RSET I 12 IIN3 I 13 IIN2 I 14 IIN1 I 15 IIN0 I 16 OVP I 17, 18 PGND S 19 FAULT O 10 ISL97635 ISL97635 (24 LD QFN) TOP VIEW SMBCLK 1 SMBDAT 2 FPWM 3 PWMO 4 GND 5 PWMI/ SMBus serial clock input SMBus serial data input and output Connect a capacitor between FPWM and GND to set the DPWM frequency. FPWM = 5.4µ ...
Page 11
... AC/DC adapter without rendering a noticable visual nuisance. The number of LEDs that can be driven by ISL97635 depends on the type of LED chosen in the application. The ISL97635 is capable of boosting up to 34.5V and typically driving 9 LEDs in series for each of the 8 channels, enabling a total of 72 pieces of the 3 ...
Page 12
... LED PWM CONTROL The ISL97635 provides four different PWM dimming methods, as described in the following. Each of these methods results in PWM chopping of the current in the LEDs for all 8 channels to provide an average LED current. During the On periods, the LED current will be defined by the value of R and BRTDC, as described in Equations 1 and 2 ...
Page 13
... The at the PWMO ISL97635 includes a soft-start feature where this current limit starts at a low value (375mA). This is stepped up to the final 3A current limit in 7 further steps of 375mA. These steps will happen over a 1ms total time, such that after 1ms, the final limit will be reached. This allows the output capacitor to be > ...
Page 14
... Should the current subsequently fall below 50% of the target, the channel will be considered an “open circuit”. Furthermore, should the boost output of the ISL97635 reach the OVP limit or should the lower over-temperature threshold be reached, all channels which are not “good” will immediately be considered as “ ...
Page 15
... This monitoring happens on a cycle by cycle basis in a self protecting way. Additionally, the ISL97635 monitors the voltage at the LX and OVP pins. At start-up, a fixed current is injected out of the LX pins and into the output capacitor. The device will not start-up unless the voltage at LX exceeds 1.2V. Furthermore, ...
Page 16
... LX current and timing GND are monitored. OVP pin monitored for excursions below 20% of OVP threshold 16 ISL97635 TABLE 1. PROTECTIONS TABLE FAILED CHANNEL ACTION GOOD CHANNELS ACTION CH0 ON and burns power CH1 through CH7 Normal CH0 goes off until chip cooled and Same as CH0 then comes back on with current reduced to 76% ...
Page 17
... R/W = Read enable at high; write enable at low SLAVE ADDRESS Master to Slave Slave to Master SLAVE ADDRESS W A COMMAND CODE Master to Slave Slave to Master 17 ISL97635 HIGH t HD:DAT t SU:DAT FIGURE 19. SMBUS INTERFACE COMMAND CODE FIGURE 20. WRITE BYTE PROTOCOL ...
Page 18
... Output Channel CH7 CH6 Register 18 ISL97635 confusion. Therefore, if the device is in the write mode where bit the slave address byte is 0x58 or 01011000b. If the device is in the read mode where bit the slave address byte is 0x59 or 01011001b. The backlight controller may sense the state of the pins at POR or during normal operation— ...
Page 19
... An SMBus Read Byte cycle to Register 0x00 returns the programmed PWM brightness level, regardless of the value of PWM_SEL. 19 ISL97635 TABLE 2B. DATA BIT DESCRIPTIONS DATA BIT DESCRIPTIONS PWM_MD = PWM mode select bit (1 = absolute brightness change), default = 0 PWM_SEL = Brightness control select bit (1 = control by PWMI control by SMBus), default = 0 ...
Page 20
... PWMI control by SMBus) default = 0 BL_CTL = BL On/Off ( Off) default = 0 FIGURE 24. DESCRIPTIONS OF DEVICE CONTROL REGISTER 20 ISL97635 PWMI = is the percent duty cycle of the PWMI For example, the Cbt = 50% duty cycle programmed in the MODE SMBus Register 0x00 and the PWM frequency is tuned to be 200Hz with an appropriate capacitor at the FPWM pin. On the other hand, PWMI is fed with a 1kHz 30% high PWM signal ...
Page 21
... A fault will not be reported in the event that the BL is commanded on and then immediately off by the system. 21 ISL97635 • When FAULT is set will remain at 1 even if the signal which sets it goes away. FAULT will be cleared when the BL_CTL bit of the Device Control Register is toggled or when written low ...
Page 22
... Manufacturer ID is not implemented REV[2..0] = Silicon rev (Rev 0 through Rev 7 allowed for silicon spins) 22 ISL97635 1_CH_SD BL_STAT OV_CURR Bit 4 (R) Bit 3 (R) Bit 2 (R) = Two LED output channels are shutdown (1 = shutdown OK) ...
Page 23
... Bit 6 (R/W) Bit 5 (R/W) BIT ASSIGNMENT 2 levels of Short-Circuit Thresholds ( 3.1V, accuracy ±15%) VSC[1..0] FSW[2] 2 levels of Switching Frequencies (1 = 1,200kHz 600kHz) FIGURE 28. DESCRIPTIONS OF CONFIGURATION REGISTER 23 ISL97635 BRTDC4 BRTDC3 BRTDC2 Bit 4 (R/W) Bit 3 (R/W) Bit 2 (R/W) BIT FIELD DEFINITIONS users to set the boost conversion switching frequency between 1.2MHz and 600kHz. ...
Page 24
... Thus, the higher the inductance, the lower the peak current capability. The ISL97635 current limit should also have to be taken into account. Output Capacitors ...
Page 25
... Schottky diode must be used. Applications High Current Applications Each channel of the ISL97635 can support up to 35mA. For applications that need higher current, multiple channels can be grouped to achieve the desirable current. For example, the cathode of the last LED can be connected to IIN0 to IIN2, this configuration can be treated as a single string with 105mA current driving capability ...
Page 26
... RGB or RGGB LED backlighting applications. Compensation The ISL97635 has two main elements in the system; the Current Mode Boost Regulator and the op amp based multi-channel current sources. The ISL97635 incorporates a All Intersil U.S. products are manufactured, assembled and tested utilizing ISO9000 quality systems. ...
Page 27
... C11 1µ/10V 1 SMBCLK PGND SMBCLK 2 SMBDAT SMBDAT PGND C13 27n/6.3V 3 FPWM ISL97635 C14 4 220n/6.3V PWMO 5 GND GND 6 PWMI/EN PWMI/ 36.6k NOTES: FOR 2 LAYERS BOARD, LAYOUT PGND (NOISY GROUND) ON TOP LAYER AND AGND (QUIET GROUND) ON BOTTOM LAYER. TIE PGND AND ...
Page 28
... Package Outline Drawing L24.4x4D 24 LEAD QUAD FLAT NO-LEAD PLASTIC PACKAGE Rev 2, 10/06 4.00 PIN 1 INDEX AREA (4X) 0.15 TOP VIEW ( TYP ) ( TYPICAL RECOMMENDED LAND PATTERN 28 ISL97635 4X A 20X 24X ± BOTTOM VIEW ± SIDE VIEW ( 20X 24X 24X 0 ...