View CXA3834AM_7306833.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

- 1 - e11711c22 sony reserves the right to change products and specifications without prior notice. this information does not convey any licens e by any implication or otherwise under any patents or other right. application circuits shown, if any, are typical examples illu strating the operation of the devices. sony cannot assume responsibility for any problems arising out of the use of these circuits. CXA3834AM led backlight driver ic description the CXA3834AM is an led driver ic with boost dc-dc converter. it enables luminance control using the peak current and pwm signal, and blinking control using the blin k signal. this ic has an optimum configuration for realizing a simple and compact power supply ci rcuit for an lcd tv equipped with a led backlight. (applications: power supply circuit, etc.) features ? shared ? uvlo function ? overheat protection function ? error detection output function (xbl_err) ? detection timer latch function when abnormalities occur ? led driver control block ? on-chip led lighting fet gate driver ? luminance adjustment function using peak current control ? luminance adjustment function using the pwm signal ? blinking control using the blink signal ? led overcurrent detection function ? dc-dc converter control block ? on-chip boost type dc-dc converter ? output overvoltage detection function ? continuous overcurrent detection function ? slope compensation function structure bicmos silicon monolithic ic package 16p-sop free datasheet http:///
CXA3834AM - 2 - absolute maximum ratings *1 allowable power dissipation reduction characteristics recommended operating conditions item symbol rating unit remarks maximum supply voltage v cc_max +24.0 v v cc xbl_err pin voltage v xbl_err ?0.3 to +24.0 v xbl_err i/o pin voltage 1 v io1 ?0.3 to v cc + 0.3 v drv, dim_sw, pwm_dim, blink, dc_dim, en vref pin voltage v ref ?0.3 to + 7.0 v vref i/o pin voltage 2 v io2 ?0.3 to vref + 0.3 v isense, ocp, comp, fb, protect, ovp_dd allowable power dissipation p d *1 mw allowable power dissipation reduction characteristics operating ambient temperature ta ?30 to +85 ? c junction temperature tj_max +150 ? c storage temperature range tstg ?55 to +150 ? c 1000 200 400 600 800 0 ?20 20 40 80 60 100 120 140 160 allowable power dissipation [mw] operating ambient temperature ta [?c] 72.1 ?c 20.7 ?c 125 ?c 193 mw 321 mw when mounted on a 4-layer board when mounted on a single layer board glass fabric base epoxy board 76 mm 114 mm t = 1.6 mm item symbol rating unit remarks supply voltage range v cc 10.0 to 18.0 v dc_dim pin input voltage v dc_dim 0.3 to 3.3 v pwm_dim pin input frequency f pwm_dim 20 k to 40 k hz rated input frequency > 1 khz 48 to 1 k hz when pwm_dim and blink pin are short circuited. pwm_dim pin minimum pulse width t pwm_dim 1.0 ? s blink pin input frequency f blink 48 to 240 hz 48 to 1 k hz when pwm_dim and blink pin are short circuited. blink pin input minimum pulse width t blink 2.0 ms 1.0 ? s when pwm_dim and blink pin are short circuited. free datasheet http:///
CXA3834AM - 3 - pin assignment block diagram 16 12 14 11 13 10 15 2 1 3 5 6 7 8 9 4 r s q q comp dc_dim protect xbl_err pwm_dim blink en v cc vref drv isense ocp dim_sw fb gnd ovp_dd oscillator clk slope v/i slope compensator vref 5.0 v 1.0 v vref l/s uvlo thermal shutdown clk slope ocp pwm vref 3.0 v 2.0 v/ 1.0 v latch 23r 10r error amplifier 2.0 v control logic latch ocp dd_en pwm_out fb_ocp dd_ovp bl_err pwm_in blink_in en 3.2 v 1.2 v comp_ovp free datasheet http:///
CXA3834AM - 4 - pin assignment pin table pin no. symbol description protective element connection destination 1 drv mosfet driver output for boost converter ? 2 isense current detection input for boost converter vref, gnd 3 ocp overcurrent detection input for boost converter vref, gnd 4 en enable signal input v cc , gnd 5 xbl_err error signal output ? 6 blink blinking signal input v cc , gnd 7 pwm_dim pwm dimming signal input v cc , gnd 8 dc_dim control voltage input v cc , gnd 9 protect protection stop time r time adjustment vref, gnd 10 comp error amplifier output for boost converter control vref, gnd 11 vref reference voltage output v cc , gnd 12 gnd gnd ? 13 v cc power supply input gnd 14 fb led current detection input vref, gnd 15 dim_sw pwm dimming mosfet driver output ? 16 ovp_dd boost converter output voltage detection input vref, gnd drv isense ocp 1 2 3 4 6 8 5 7 14 13 12 11 9 10 en top view xbl_err blink pwm_dim dc_dim ovp_dd dim_sw fb v cc gnd vref comp 16 15 protect free datasheet http:///
CXA3834AM - 5 - pin description pin no. symbol i/o typical pin voltage equivalent circuit description 1 drv o v cc to gnd mosfet driver output for boost converter (connect to the boost converter nmos gate.) 2 isense i/o 1.0 v to gnd current detection input for boost converter (connect to a slope compensation resistor.) 3 ocp i 1.0 v to gnd overcurrent detection input for boost converter (connect to a current detection resistor.) 4en iv cc to gnd enable signal input 5xbl_erri/ov cc to gnd error signal output (connect to a pull-up resistor.) 1 drv v cc gnd nch pch nch pch 2 isense gnd vref pch pch pch 3 ocp gnd vref pch pch 4 en gnd v cc pch 5 xbl_err v cc gnd nch nch pch free datasheet http:///
CXA3834AM - 6 - 6 blink i 3.3 v to gnd blinking signal input 7 pwm_dim i 3.3 v to gnd pwm dimming signal input 8 dc_dim i 3.3 v to gnd control voltage input (connect to the r-c filter output side.) 9 protect i/o 3.0 v to gnd protection stop timer time adjustment (connect to the timer adjusting capacitor.) 10 comp i/o 3.8 v to gnd error amplifier output for boost converter control (connect the phase compensation circuit between comp and gnd.) pin no. symbol i/o typical pin voltage equivalent circuit description 6 blink v cc gnd pch nch 7 pwm_dim v cc gnd pch nch 8 dc_dim v cc gnd pch pch gnd vref nch nch 9 protect pch 10 comp gnd vref pch pch nch free datasheet http:///
CXA3834AM - 7 - 11 vref o 5.0 v internal supply voltage output (connect a stabilizing capacitor.) 12 gnd gnd 13 v cc power supply input (connect a stabilizing capacitor.) 14 fb i 1.0 v to gnd led current detection input (connect to a current detection resistor.) 15 dim_sw o v cc to gnd mosfet driver output for pwm dimming (connect to the dimming nmos gate.) 16 ovp_dd i 3.2 v to gnd output voltage detection input for boost converter (connect to an output voltage detection resistor.) pin no. symbol i/o typical pin voltage equivalent circuit description 11 vref gnd v cc pch nch nch gnd vref 14 fb pch pch pch 15 dim_sw gnd v cc pch nch 16 ovp_dd gnd vref pch pch free datasheet http:///
CXA3834AM - 8 - electrical characteristics ? shared blocks ( unless otherwise specified, ta = 25 ? c, v cc = 12 v, en = 3.3 v, pwm_dim = 3.3 v, blink = 3.3 v, dc_dim = 3.3 v ) power supply block (v cc pin) reference voltage block (vref pin) enable signal input block (en pin) error output block (xbl_err pin) protective detection pin (protect pin) item symbol measurement conditions min. typ. max. unit operation start voltage v cc_on 9.0 9.5 10.0 v operation stop voltage v cc_off 8.5 9.0 9.5 v hysteresis width ? v cc v cc _on ? v cc _off 0.3 0.5 0.7 v operating current consumption i cc1 fb = 1.5 v * non switching ?1.151.65ma current consumption when stopped i cc2 en = 0 v pwm_dim = 0 v ?0.851.10ma item symbol measurement conditions min. typ. max. unit output voltage v ref 4.85 5.00 5.15 v input stability v ref_line v cc = 10.0 v to 18.0 v, no load ?1050mv load stability v ref_load iout = 0.1 m to 5.0 ma ? 20 50 mv item symbol measurement conditions min. typ. max. unit high level detection voltage v en_h 1.9 2.0 2.1 v low level detection voltage v en_l 0.9 1.0 1.1 v hysteresis width ? v en v en_h ? v en_l 0.9 1.0 1.1 v pin input resistance r en en = 1.0 v 200 300 400 k ? item symbol measurement conditions min. typ. max. unit output low voltage v xbl_err_l en = 0 v, iout = ?3 ma ? 0.15 0.3 v output off leak current i xbl_err_off xbl_err = 18 v ? ? 1.0 ? a item symbol measurement conditions min. typ. max. unit latch stop detection voltage v protect 2.9 3.0 3.1 v charge current i protect_chg protect = 1.0 v, pwm_dim = 12.0 v 8.0 10.0 12.0 ? a discharge current i protect_rst protect = 1.0 v 0.8 1.0 1.2 ? a free datasheet http:///
CXA3834AM - 9 - ? led driver control block ( unless otherwise specified, ta = 25 ? c, v cc = 12 v, en = 3.3 v, pwm_dim = 3.3 v, blink = 3.3 v, dc_dim = 3.3 v ) mosfet driver output block (dim_sw pin) *1 rise time and fall time use v cc ? 0.1 to v cc ? 0.9 as the judgment voltages. error amplifier input circuit block (fb pin, dc_dim pin) pwm dimming signal input block (pwm_dim pin) blink signal input block (blink pin) item symbol measurement conditions min. typ. max. unit output rise time *1 t r_dim_sw c load = 1000 pf ? 30 60 ns output fall time *1 t f_dim_sw c load = 1000 pf ? 30 60 ns output high voltage v dim_sw_h iout = 10 ma 11.90 11.95 ? v output low voltage v dim_sw_l pwm_dim = 0 v, iout = ?10 ma ? 0.05 0.1 v item symbol measurement conditions min. typ. max. unit feedback control voltage 1 v fb_ref1 dc_dim = 3.3 v 0.98 1.00 1.02 v feedback control voltage 2 v fb_ref2 dc_dim = 1.65 v 0.495 0.500 0.505 v fb pin pull-up current i fb fb = 0.1 v 0.05 0.1 0.2 ? a overcurrent detection voltage v fb_ocp 1.9 2.0 2.1 v dc_dim pin input resistance r dc_dim dc_dim = 1.0 v 700 990 1300 k ? item symbol measurement conditions min. typ. max. unit high level input voltage v pwm_dim_h 2.0 ? v cc ? 2.0 v low level input voltage v pwm_dim_l ??1.0v pin input resistance r pwm_dim pwm_dim = 1.0 v 200 300 400 k ? item symbol measurement conditions min. typ. max. unit high level input voltage v blink_h 2.0 ? v cc ? 2.0 v low level input voltage v blink_l ??1.0v pin input resistance r blink blink = 1.0 v 200 300 400 k ? free datasheet http:///
CXA3834AM - 10 - ? dc-dc converter control block ( unless otherwise specified, ta = 25 ? c, v cc = 12 v, en = 3.3 v, pwm_dim = 3.3 v, blink = 3.3 v, dc_dim = 3.3 v ) mosfet driver output block (drv pin) *1 rise time and fall time use v cc ? 0.1 to v cc ? 0.9 as the judgment voltages. error amplifier output block (comp pin) current detection circ uit block (isense pin) overcurrent detection block (ocp pin) output voltage detection block (ovp_dd pin) note) shipping inspection is performed at room temper ature. (the design is guaranteed with respect to temperature fluctuation.) item symbol measurement conditions min. typ. max. unit output rise time *1 t r_drv c load = 1000 pf ? 35 70 ns output fall time *1 t f_drv c load = 1000 pf ? 25 50 ns output high voltage v drv_h iout = 10 ma ( design guarantee ) 11.85 11.90 ? v output low voltage v drv_l en = 0 v, iout = ?10 ma ? 0.03 0.1 v oscillation frequency f osc isense = 0 v, ocp = 0 v, fb = 0 v 95 100 105 khz maximum on duty d max isense = 0 v, ocp = 0 v, fb = 0 v 85 90 95 % item symbol measurement conditions min. typ. max. unit transconductance gm (design guarantee) ? 520 ? ? a/v output source current i comp_h fb = 0 v, comp = 3.0 v 60 80 100 ? a output sink current i comp_l fb = 1.5 v, comp = 0.5 v 60 80 100 ? a item symbol measurement conditions min. typ. max. unit slope compensation output current i slope fb = 0 v, opc = 0 v (peak current value during maximum on duty operation) (design guarantee) ?50? ? a item symbol measurement conditions min. typ. max. unit overcurrent limit detection voltage v ocp fb = 0 v, isense = 0 v 0.9 1.0 1.1 v dd blanking pulse width t dd_blk ocp = 1.5 v, fb = 0 v 350 500 650 ns ocp pin pull-up current i ocp ocp = 0.1 v 0.05 0.1 0.2 ? a item symbol measurement conditions min. typ. max. unit output overvoltage detection voltage v ovp 3.1 3.2 3.3 v ovp_dd pin pull-up current i ovp ovp_dd = 0.1 v 0.05 0.1 0.2 ? a free datasheet http:///
CXA3834AM - 11 - detailed description of blocks start-up/stop CXA3834AM operation starts when voltage of 9.5 v (typ.) or more is applied to the v cc pin. when this voltage is applied to the v cc pin, the internally generated reference voltage (vref pin) is generated and the reset state (por) is canceled. in addition, v cc has a built-in uvlo function, and when the v cc pin voltage falls to 9.0 v (typ.) or less, the ic enters the reset state, the dc-dc converter stops operation and the dim_sw output goes to low output regardless of the input signals of other pins. when the v cc pin voltage rises to 9.5 v or more again, the reset is canceled and stopped functions can be operated. fig. 1. start-up and stop operation after power-on enable (en) dc-dc converter and led driver operations are enabled by setting the en pin to 2.0 v or more. in addition, the pwm_dim pin and the blink pin must both be high for the dc-dc converter to start operation. when the en pin falls to 1.0 v or less, the dc-dc converter stops operating instantly, but the signal input to the pwm_dim pin is output on the dim_sw pin. in addition, when the en pin is low, the signal input to the pwm_dim pin is output as is on the dim_sw pin even when the blink pin is low. fig. 2. operation during voltage input to the en pin reset release reset reset 9.5 v 12 v 9.0 v v cc por (internal signal) 2.0 v en pwm_dim blink dim_sw 1.0 v drv (dc-dc converter operation) free datasheet http:///
CXA3834AM - 12 - dimming control block the CXA3834AM has an on-chip constant current mode boost dc-dc converter to generate the voltage required to light the led elements. the voltage (vout) boosted by the dc-dc converter is applied to the anode side of the multiple led elements connected in series, and when a high voltage is input to the pwm_dim pin, the dim_sw pin also outputs a high volt age, the external fet is driven, and current flows to the led elements. fig. 3 shows a schematic of the operating circuit. fig. 3. CXA3834AM oper ating circuit diagram isense drv vout fb dim_sw vin rfb dc_dim 23r 10r i led ocp pwm_dim blink dc-dc controller control logic CXA3834AM free datasheet http:///
CXA3834AM - 13 - led luminance adjustment the CXA3834AM can adjust the led luminance using two different settings. [luminance adjustme nt by pwm control] the pulse input to the pwm_dim pin is output on the dim_sw pin. the external fet gate is driven and current flows to the led elements in accordance with the dim_sw pin output. the average current flowing to the led elements is proportional to the dut y of the pulse input to the pwm_dim pin, so the led element luminance can be adjusted by controlling the duty. (see fig. 4.) use a CXA3834AM pwm_dim pin input pulse with a frequency between 20 hz and 40 kh (when pwm_dim and blink pin are short circuited, use them detween 48 hz and 1 khz), with a minimum high pulse width of 1 ? s. [luminance adjustment by peak current control] the current flowing to the led elements is converted to a voltage by the fb resistor (rfb), and this voltage monitored by the fb pin of the cxa3834a m. the dc-dc converter compares the fb pin voltage with the value 10/33 times the dc_dim pin voltage (v dc_dim ), and controls the output voltage (vout) to hold the same potential. that is to say, the current flowing to the led elements or the fb pin resistor can be controlled by controlling the dc _dim pin voltage. the current flowing to the led elements is determined by the following formula. fig. 5 shows the relationship between the dc_dim pin voltage and fb pin resistance value and the current flowing to the led elements. the dc_dim pin is pulled down internally by resistance of 990 k ? (typ.). when connecting a smoothing rc filter to the dc_dim pin, determine the const ants in consideration of the ic internal impedance. i led v dc_dim 10 33 ------ ? ?? ?? rfb [a] ? = 100 75 50 25 50 100 pwm_dim duty [%] dc_dim = 3.3 v rfb = 10 rfb = 5 pwm_dim_duty = 100 % rfb = 10 pwm_dim_duty = 100 % 1.65 3.3 dc_dim input voltage [v] led average current [ma] 200 150 100 50 led current [ma] fig. 4. pwm_dim_duty - i led characteristics fig. 5. dc_dim voltage - i led characteristics free datasheet http:///
CXA3834AM - 14 - led blinking control (blinking) the CXA3834AM has a blink pin, and the led elements can be made to perform blinking operation by switching the signal input to the blink pin between high and low. when the blink signal is low, the dim_sw pin is forcibly set to low output (led elements off), and at the same time the dc-dc converter output voltage ripple is suppressed, so dc-dc converter boost operation (drv output) is also forcibly stopped. fig. 6 shows operation relative to the signal input to the blink pin. fig. 6. timing chart during blinking operation use a CXA3834AM blink pin input pulse with a maximum frequency of 240 hz with a minimum high pulse width of 2 ms. (when pwm_dim and blink pin are short circuited, use them with a maximum frequency of 1 khz with a minimum pulse width of 1 ? s.) for applications that do not perform blinking operation, connect the blink pin to the vref pin. blink pwm_dim dim_sw drv led off on off on off on off on off on off on off off off on on free datasheet http:///
CXA3834AM - 15 - led overcurrent det ection circuit block the CXA3834AM has an overcurrent detection function to detect abnormalities in the current flowing to the led elements. fig. 7 shows the fb pin peripheral equivalent circuit. fig. 7. fb pin peripheral equivalent circuit when a fb pin voltage of 2.0 v (typ.) or more is detected (led_ocp), charging to the protect pin starts (charge current: 10 ? a (typ.)). led_ocp is detected continuously, and when the protect pin voltage reaches 3 v, the ic is set to stop mode (latch st op). charging to the protect pin is performed only while led_ocp is detected. when led_ocp is not detected, the protect pin discharges at 1 ? a (typ.). this ic generates a blanking pulse to prevent the abov e-mentioned overcurrent detection from malfunctioning. this blanking pulse is approximately 500 ns (min.), and prevents false overcurrent detection due to the inrush current that occurs when dim_sw switches from low to high. the fb pin voltage is controlled by 10/33 times the dc_dim pin voltage, but note that overcurrent is detected more easily when the dc_dim pin voltage is set too high. fig. 8 shows the timing chart during led_ocp operation. fig. 8. led_ocp detection timing chart drv vout fb dim_sw rfb dc_dim 23r 10r i led dc-dc controller pwm_dim protect 2.0 v blanking pulse control logic vref 3.0 v err_rst err_set 2.0 v pwm_dim blanking pulse fb err_set (ocp detection) protect free datasheet http:///
CXA3834AM - 16 - dc-dc converter control block oscillator circuit block the CXA3834AM dc-dc converter oscillating frequency is fi xed to 100 khz (typ.) by the internal circuit. the maximum on duty is 90 % (typ.), and the boost c onverter mosfet on time is normally proportional to the comp pin voltage. fig. 9 shows the oscillator peripheral equivalent circuit. fig. 9. oscillator peripheral equivalent circuit [steady-state operation] when the clk pulse is output from the oscillator, the drv pin output goes high and current starts to flow to the choke coil. the current that flows to the choke coil is converted to a voltage (vocp) by the current detection resistor (rcs). the isense pin voltage (visense) is the sum of vocp and the voltage generated by the internal slope compensation current flowing to the slope compensation resistor (rslope), and is input to the pwm comparator non-inverted input pi n. when visense rises to the pwm comparator inverted input pin (pwm_in) voltage or more, the reset signal is generated and the drv pin output goes low. the pwm_in voltage (vpwm_in) is the voltage obtained by level-shifting the comp pin voltage (vcomp), and is determined approxima tely by the following calculation formula. here, vt corresponds to the internal transistor threshold voltage, and is approximately 0.8 v in the CXA3834AM. vpwm_in = (vcomp ? vt) ? 3/5 when the current flowing to the choke coil is low and visense does not reach the pwm_in voltage during one cycle period, the drv output automatically goes low when the on duty reaches 90 % (typ.). the above operation is repeated and boost operation is continued until the prescribed current flows to the led elements. fig. 10 shows the dc-dc converter operation timing chart during steady-state operation. fig. 10. dc-dc converter operation timing chart comp isense fb dc_dim drv vout vin 10r 23r ocp oscillator 1.0 v error amplifier pwm slope compensator v/i clk slope ocp rcs rslope rfb vref pwm comparator vocp visense pwm_in l/s sq q r clk drv il pwm_in vocp + visense free datasheet http:///
CXA3834AM - 17 - [overcurrent detection] the peak current flowing to the choke coil is constantly monitored by the ocp pin, and when the ocp pin voltage reaches 1.0 v (typ.), the drv pin output is forcibly set low (pulse-by-pulse operation). after overcurrent detection, the protect pin is charged at 10 ? a (typ.) until the next cycle starts. when overcurrent is detected continuously, the pr otect pin is continuously charged, and when the protect pin voltage reaches 3 v, the ic latch stops. the CXA3834AM generates a blanking pulse to pr event false ocp pin overcurrent detection. this blanking pulse is 500 ns (typ.), and prevents false overcurrent detection due to the inrush current that occurs when the drv pin output switches from low to high. [slope compensation] when the constant current mode boost converter is set so that the drv pin on duty is 50 % or more, sub-harmonic oscillation may occur. the cxa3834a m can operate the boost converter stably even when the on duty is 50 % or more by inserting a series resistor (rslope) to the isense pin and applying slope compensation. for details on sub-harmonic oscillation and slope compensation, see the application notes. free datasheet http:///
CXA3834AM - 18 - comp pin hold circuit block the fb pin voltage temporarily goes to 0 v while a low signal is input to the pwm_dim pin and current is not flowing to the led elements (dim_sw pin output signal low period), so the comp pin voltage and the dc-dc converter output voltage rise temporarily. in th is case, when a high signal is input to the pwm_dim pin in the next cycle, a transient current flows to the led elements. in the CXA3834AM, the comp pin voltage immediately before a low signal is input to the pwm_dim pin is held, and dc-dc converter operation continues. by holding the comp pin voltage, operation can be performed without a transient current flowing to the led elements even when the pwm_dim pin signal goes high in the next cycle. similar operation is also performed when the blink pin input signal is low, so that the comp pin output voltage is held even when a low signal is input to the blink pin and boost operation stops. fig. 11 and fig. 12 show the comp pin hold function timing chart and the comp pin peripheral equivalent circuit, respectively. fig. 11. comp pin hold function timing chart fig. 12. comp pin peripheral equivalent circuit when the signal input to the pwm_dim pin has a high frequency (up to approximately 40 khz) and low duty, the effect of the hold function reduces the comp pin response speed, and may influence the start-up time and the led current characteristics. make thorough evaluation before determining the phase compensation constants rcomp, ccomp1 and ccomp2 c onnected to the comp pin. for details, see the application notes. in addition, this ic detects the c ondition that fb pin voltage is fixed to low when no current flows to the led elements due to error conditi ons such as drv pin open. therefore, this ic has a function to output low level of xbl_err signal w hen comp voltage becomes 2.8 v (min.) or more. blink pwm_dim comp vout led_current hold hold hold hold hold hold hold hold hold comp isense fb dc_dim drv 10r 23r sq q r error amplifier l/s hold_sw on/off blink pwm_dim control logic dim_sw rcomp ccomp1 pwm ccomp2 free datasheet http:///
CXA3834AM - 19 - output voltage detection circuit block fig. 13 shows the ovp_dd pin peripheral equivalent circuit. fig. 13. ovp_dd pin peripheral equivalent circuit the ovp_dd pin has a protective function that detects dc-dc converter output overvoltage. when an ovp_dd pin voltage of 3.2 v (typ.) or more is detected (ovp), the ic instantly latch stops. to properly light the led elements during normal operation, set the br eeder resistance ratio (rovp1/rovp2) so that the voltage input to the ovp_dd pin is 3.2 v or less. in addition, pull-up current of 0.1 ? a (typ.) is supplied from inside the ic in consideration of the case when the ovp_dd pin is open. when the ovp_dd pin is open, the pin voltage is pulled-up to approximately the vref pin voltage, ovp is detected, and the ic latch stops. therefore, set the rovp2 resistance value to a value that does not affect this 0.1 ? a current. drv fb rfb dc_dim 23r 10r i led dc-dc controller vout vin ovp_dd 3.2 v control logic ovp vref rovp2 rovp1 free datasheet http:///
CXA3834AM - 20 - protective detection functions the CXA3834AM has various built-in protective func tions to realize stable power supply operation. when an error is detected by a protective function, the xbl_err pin outputs a low signal, and either timer latch operation is performed by charging the protect pin or instant latch stop operation is performed. table 1 lists the protective functions, error conditions, and operation after detection. when the ic latch stops after an error is detected, dc-dc converter operation stops and the dim_sw pin outputs low. when the ic has performed latch operation (latch1) , the latch can be canceled by turning the power supply off and then on again, or by stopping and then restarting en supply. when latch stop operation was performed due to overheat protective detection (tsd) (latch2), the latch can be canceled only by turning the power supply off and then on again. table 1. list of protective functions [backlight error detection function] when error number 1, 2, 6, 7, 8 or 9 in table 1 is detected, the xbl_err pin outputs low, and current is pulled into the ic from an external voltage source via a pull-up resistor. when a backlight error is not detected, the xbl_err pin is high impedance, so the external pull-up voltage source voltage is generated on the pin. [timer latch function] when error number 3, 4, 5, 6, 7, 8 or 9 in table 1 is detected, charging to the protect pin starts, and the ic latch stops when the protect pin voltage reaches 3 v. the time after an error is detected until the latch stop operation can be set by connecting a capacit or to the protect pin. fig. 14 and fig. 15 show the protect pin peripheral equivalent circuit an d the error detection timing chart, respectively. [instant latch function] when error number 10 or 11 in table 1 is detected, the ic instantly latch stops, and dc-dc converter and dimming operation also stop. when the ic has latch stopped, the xbl_err pin outputs low. no. protective function detection conditions protect pin charging xbl_err = low output backlight error detection function (xbl_err = low output) 1 mos_fet open detection when the comp pin output stays high ? 2 vref overvoltage detection 1 vref pin voltage > 6.0 v ? timer latch function (protect pin charging) 3 dc-dc overcurrent detection (dd_ocp) ocp pin voltage > 1.0 v ? 4 led overcurrent detection (led_ocp) fb pin voltage > 2.0 v ? 5 drv pin error detection drv pin input/output mismatch ? backlight error detection and timer latch function 6 pwm_dim pin protective detection pwm_dim pin voltage > v cc ? 0.5 v 7 blink pin protective detection blink pin voltage > v cc ? 0.5 v 8 dc_dim pin protective detection dc_dim pin voltage > v cc ? 0.5 v 9 vref overvoltage detection 2 vref pin voltage > 5.5 v instant latch function 1 (latch1) 10 dc-dc output overvoltage protection (ovp) ovp_dd pin voltage > 3.2 v ? 11 protect latch stop detection protect pin voltage > 3.0 v ? instant latch function 2 (latch2) 12 overheat detection (tsd) tj > 140 ? c? free datasheet http:///
CXA3834AM - 21 - fig. 14. protect pin equivalent circuit when an error is detected (err_set = high), stable current of 10 ? a flows out from the ic via the protect pin. during normal operation (e rr_rst = high), stable current of 1 ? a flows into the ic via the protect pin. fig. 15. error detection timing chart the timer time when an error is continuously detected can be expressed by the following formula. protect vref 3.0 v err_set err_rst protect logic internal reference voltage 1 a 10 a cp rst err_set protect pin current protect latch protect latch detected dischg dischg dischg dischg chg chg chg 3.0 v (internal_signal) tcp ( ? f ? 3.0 v 10 ? a ? ? 0.3 cp (s) ? == free datasheet http:///
CXA3834AM - 22 - [state transition diagram] fig. 16 shows the state transitions of this ic. fig. 16. state transition diagram note) reset = high condition : v cc _uvlo = h or en = l or vref_uvlo = h or vref_ovlo = h latch1 = high condition : protect = h or ovp = h latch2 = high condition : tsd = h reset = low condition : v cc _uvlo = l and en = h and vref_uvlo = l and vref_ovlo = l initial state error state 2 error state 1 normal operating state xbl_err = l xbl_err = l xbl_err = l xbl_err = hi-z v cc _uvlo = h latch2 = h latch1 = h latch2 = h latch2 = h reset = h reset = h reset = l free datasheet http:///
CXA3834AM - 23 - application circuit fig. 17. application circuit (assum ing vin = 150 v, vout = 300 v, i led = 200 ma) 1v vin 200 h 33 f 2.2 k 0.47 f 4.7 k 440 k 660 k 6.3 k 5 CXA3834AM 1.0 f 1.0 f 0.1 pwm_dim blink dc_dim 12 v 12 v bl_on 10 k 10 k 4.7 k bl_err 16 1 2 3 4 5 6 7 8 12 9 10 11 13 14 15 protect drv ocp fb dim_sw xbl_err blink pwm_dim dc_dim comp vref gnd v cc isense ovp_dd en vout 0.47 f 2.2 k xx application circuits shown are typical examples illustrating the operation of the devices. sony cannot assume responsibility fo r any problems arising out of the use of these circuits or for any infringement of third party patent and other right due to same. free datasheet http:///
CXA3834AM - 24 - example of representative characteristics vref pin output voltage v cc _uvlo operation start voltage v cc _uvlo operation stop voltage 4.85 4.80 4.90 4.95 5.00 5.05 5.10 5.15 5.20 current consumption when stopped operating current consumption 8.8 9.0 9.2 9.4 9.6 9.8 10.0 10.2 vref pin output voltage [v] current consumption when stopped [ma] operating current consumption [a] v cc _uvlo operation start voltage [v] 9.6 9.4 9.2 9.0 8.8 8.6 8.4 v cc _uvlo operation stop voltage [v] ?30 0 30 60 90 120 temp [?c] ?30 0 30 60 90 120 temp [?c] ?30 0 30 60 90 120 temp [?c] protect pin latch detection voltage 3.15 3.10 3.05 3.00 2.95 2.90 2.85 latch detection voltage [v] ?30 0 30 60 90 120 temp [?c] 1.2 1.1 1.0 0.9 0.8 0.7 0.6 2.0 1.5 1.0 0.5 0 ?30 0 30 60 90 120 temp [?c] ?30 0 30 60 90 120 temp [?c] free datasheet http:///
CXA3834AM - 25 - fb pin control voltage 1 0.97 0.98 0.99 1.00 1.01 1.02 1.03 control voltage 1 [v] ?30 0 30 60 90 120 temp [?c] drv pin oscillating frequency 94 92 96 98 100 102 104 106 108 oscillating frequency [khz] ?30 0 30 60 90 120 temp [?c] dim_sw pin rise time 0 10 20 30 40 50 60 70 rise time [ns] ?30 0 30 60 90 120 temp [?c] dim_sw pin fall time 0 10 20 30 40 50 60 70 fall time [ns] ?30 0 30 60 90 120 temp [?c] fb pin control voltage 2 0.506 0.504 0.502 0.500 0.498 0.496 0.494 control voltage 2 [v] ?30 0 30 60 90 120 temp [?c] fb pin overcurrent detection voltage 1.85 1.90 1.95 2.00 2.05 2.10 2.15 overcurrent detection voltage [v] ?30 0 30 60 90 120 temp [?c] free datasheet http:///
CXA3834AM - 26 - ovp_dd pin overvoltage detection voltage 3.35 3.30 3.25 3.20 3.15 3.10 3.05 overvoltage detection voltage [v] ?30 0 30 60 90 120 temp [?c] comp pin source current source current [a] ocp pin overcurrent detection voltage 0.85 0.80 0.90 0.95 1.00 1.05 1.10 1.15 1.20 overcurrent detection voltage [v] ?30 0 30 60 90 120 temp [?c] comp pin sink current sink current [a] drv pin maximum on duty 96 94 92 90 88 86 84 maximum on duty [%] ?30 0 30 60 90 120 temp [?c] ?30 0 30 60 90 120 temp [?c] 50 60 70 80 90 100 110 50 60 70 80 90 100 110 ?30 0 30 60 90 120 temp [?c] free datasheet http:///
CXA3834AM - 27 - package outline (unit: mm) mitsui ht: 875340660 marking a3834m free datasheet http:///
CXA3834AM - 28 - sony corporation package outline (unit: mm) sdt: 875339910 marking c b c:CXA3834AM b: lot no. (max. 7) %!!? (control no.) -~1g1s (week manufactured) -~1g ( -?r
t ) (year manufactured) free datasheet http:///

▲Up To Search▲

Price & Availability of CXA3834AM

	To Download CXA3834AM Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .