1 dual-channel laser diode driver with apc amplifier for multi-beam printers isl58125 the isl58125 is a high-performance dual channel laser driver that provides controlled current to grounded laser diodes. a bias current is summed with the switched current at the iout output, allowing the user to optimize laser diode performance. output switched current flows when the lvds signal data is high. the output current returns to the fixed-threshold value when data is low. complete i out shut-off is achieved by holding both of the disx pins hi, which will override all other control pins. a fast settling apc amplifier connects directly to the monitor diode. the isl58125 does not exhibit any time-dependent droop since the calibration gain is stored as a digital number. features ? voltage-controlled output current source ? very few external components needed ? internal lvds termination resistors ? 300mhz switching ? 110ma output current per channel ? rise time < 500ps ? fall time < 500ps ? apc loop for write power control ? fast settling apc amplifier ? single +5v supply (10%) ? disable feature for power-up protection and conserving power ? zero droop ? pb-free (rohs compliant) load configuration ? common-cathode lds, common-anode pd applications ? laser printer applications ? laser diode current switching ordering information part number (note) part marking package tape & reel (pb-free) pkg. dwg. # ISL58125CRZ-T13 58125 crz 28 ld qfn l28.4x5a 1. please refer to tb347 for de tails on reel specifications. 2. these intersil pb-free plasti c packaged products employ special pb-free material se ts, molding compounds/die attach materials, and 100% matte tin plate plus anneal (e3 termination finish, which is rohs compliant and compatible with both sn pb and pb-free soldering operations). intersil pb-free products are msl classified at pb-free peak reflow temper atures that meet or exceed the pb-free requirements of ipc/jedec j std-020 . 3. for moisture sensitivity level (msl), please see device information page for isl58125 . for more information on msl please see techbrief tb363 . iout1 gnd pdin iout2 july 22, 2013 fn6625.1 caution: these devices are sensitive to electrostatic discharge; follow proper ic handling procedures. 1-888-intersil or 1-888-468-3774 | copyright intersil americas llc 2009, 2013. all rights reserved intersil (and design) is a trademark owned by intersil corporation or one of its subsidiaries. all other trademarks mentioned are the property of their respective owners.
2 fn6625.1 july 22, 2013 pin configuration isl58125 (28 ld qfn) top view cal2b thermal pad 22 21 20 19 18 17 16 28 27 26 25 24 9 10 11 12 13 1 2 3 4 5 6 7 nc gnd vcc iout1 vcc iout2 vcc data1 data1b data2 data2b gnd dis1 cal1b vc1 vc2 errb ivout2 rset rbias1 rbias2 8 15 14 23 dis2 nc pdin slpen ivout1 rovr isl58125
3 fn6625.1 july 22, 2013 pin descriptions pin name i/o type description data1 i lvds laser #1 switching control data1b i lvds laser #1 switching control data2 i lvds laser #2 switching control data2b i lvds laser #2 switching control gnd ground ground dis1 i digital dis1 = low selects iout1 dis2 i digital dis2 = low selects iout2 vc1 ianalog voltage controlling laser #1 switching cu rrent; 0v to 2v input for 0% to 100% output vc2 i analog voltage controlling laser #2 switching current nc no connect no connect errb o open drain errb = low when output current is max or over heat or under supply voltage ivout1 ivout2 o analog calibrate channel with an external trimpot to gnd adjust the iv amplifier gain rset o analog bandgap derived internal reference rovr i analog resistor sets the peak current at which the error pin errb is pulled. pdin i analog photo diode input to the iv amplifier rbias1 rbias2 analog resistors set bias threshold current. se e ?applications inform ation? on page 8 for more details. iout2 o analog laser #2 current output iout1 o analog laser #1 current output vcc power supply voltage cal1b i ttl samples the laser #1 for apc; active low cal2b i ttl samples the laser #2 for apc; active low slpen i ttl enable sleep mode when slpen = disx = hi thermal pad exposed thermal pad should be soldered to gnd note: pins with the same name are not necessary internally co nnected together. ldd pins must not be used for connecting together external components or features. isl58125
4 fn6625.1 july 22, 2013 important note: all parameters having min/ma x specifications are guaranteed. typical va lues are for informat ion purposes only. u nless otherwise noted, all tests are at the specified temperature and are pulsed tests, therefore: t j = t c = t a standard specification conditions: unless otherwise indica ted, all tables are: vcc = 5.0v, dis = lo, t a = +25c, r set = 3.0k absolute maximum ratings (t a = +25c) recommended operating conditions voltages applied to: v cc . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.5v to 6.0v all inputs . . . . . . . . . . . . . . . . . . . .-0.5v to v cc + 0.5v i out . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.5v to v cc lvds max current inputs . . . . . . . . . . . . . . . . . . . . 5ma esd rating human body model . . . . . . . . . . . . . . . . . . . . . . . . . 3kv charged device model . . . . . . . . . . . . . . . . . . . . . . 1.5kv thermal resistance (typical, note 4) ja (c/w) 28 lead qfn . . . . . . . . . . . . . . . . . . . . . . . 42 operating ambient temperature range . . . . . . 0c to +85c maximum junction temperature . . . . . . . . . . . . . . . +150c storage temperature range . . . . . . . . . . . -65c to +150c pb-free reflow profile . . . . . . . . . . . . . . . . . .see link below http://www.intersil.com/pbfree/pb-freereflow.asp caution: do not operate at or near the maximum ratings listed for extended periods of time. exposure to such conditions may adv ersely impact product reliability and result in failures not covered by warranty. note: 4. ja is measured in free air with the component mounted on a high effective thermal conductivity test board with ?direct attach? features. see tech brief tb379. electrical specifications standard conditions, and/or as noted. parameter description conditions min (note 5) typ max (note 5) unit v cc supply voltage 4.5 5.0 5.5 v isdis supply current (disable d) disx = slpen = hi 0.3 1.0 ma is2 supply current (standby) disx = hi 22 31 ma v lo low voltage threshold all ttl inputs 1.2 v v hi high voltage threshold all ttl inputs 2.8 v i lo input low current all ttl inputs -20 -10 a i hi input high current all ttl inputs 1 a v shut vcc shut down voltage 2.5 2.9 v v lvds lvds input level differentia l, with vcm = 1.25v 0.2 v v cmr lvds common mode voltage range 300mv p-p 0.2 2.2 v v c control voltage 0.3 2.6 v r te r m i n a t i o n internal lvds termination resistor 180 eerb vout low digital output sink capabili ty errb pin, sinking 5ma 0.4 v i ovr-2k overcurrent trip point rovr = 2k , errb pin goes low 43 ma vcc unr undervoltagetrip point err b pin goes low, no i out current 2.6 v laser amplifier output standard conditions and/or as noted. parameter description conditions min (note 5) typ max (note 5) unit i out iout sw-max switched output current vc = 2.6v 75 81 ma iout bias-max bias output current r bias = 1k 20 35 ma i off output off current disx pins set to high -75 0 +75 a freq op operating frequency i out = maximum switch current 200 mhz isl58125
5 fn6625.1 july 22, 2013 timing diagram iout psrr i out supply sensitivity i out = 20ma, v cc = 5v 10% 13 %/v t r-iout i out rise time 10% to 90%; typical ld for printer 0.5 ns t f-iout i out fall time 90% to 10%; typical ld for printer 0.7 ns outenx_t on i out on propagation delay datax crossing to i out at 50% of final value 5 7 ns vc t pd_vc-iout propagation time of vc 0.75v to 1.25v step 16 ns t r_vc-iout rise time of i out from vc 10% to 90%; resistive load, r load = 10 25 ns t f_vc-iout fall time of i out from vc 90% to 10%; resistive load, r load = 10 22 ns vc bw bandwidth of vc 14 mhz laser amplifier output standard conditions and/or as noted. (continued) parameter description conditions min (note 5) typ max (note 5) unit apc electrical specifications standard conditions and/or as noted. parameter description conditions min (note 5) typ max (note 5) unit t apc-50 apc response time 0v to 2v step of vc 7.5 s ivgain iv amplifier gain exte rnal resistor riv = 500 3.1 k note: 5. parameters with min and/or max limits are 100% tested at +2 5c, unless otherwise specified. temperature limits established by characterization and are not production tested. vc i out dis calb data(lvds) fixed bias level set by r bias off i out rises to its vc defined value using the last calibration gain setting in <1s off cal level isl58125
6 fn6625.1 july 22, 2013 i out control dis1 dis2 data1 data2 cal1 cal2 slpen i out1 i out2 power-down (sleep mode) 11xxxx1 off off standby (full standby current, no i outs ) 11xxxx0 off off normal drive 0 1 0 0 1 1 0 on, bias only off 1 0 0 0 1 0 0 off on, bias only 0 0 x x 0 1 x on, cal to level set by vc off 00xx10x off on, cal to level set by vc 001111x on on 011111x on off 101111x off on note: data1 and data2: 1 implies data>datab, 0 implies data 7 fn6625.1 july 22, 2013 typical application slpen rbias1 vc2 nc bandgap ref. data1 data2 data2b data1b logic block iv amplifier vc1 iout dis2 errb iout1 vcc rset lasers 0.1f 0.1f 4.7f 68 68 bead 4.7f + - + - switching driver switching driver vcc vcc ivout2 + - + - dis1 gnd pdin ivout1 + - cal2b cal1b gnd gain control cal. pot cal. pot nc rbias2 rovr + - + - +5v gain control isl58125
8 fn6625.1 july 22, 2013 applications information apc system overview as the laser heats up, or ages, its output power declines relative to the applied current, so some form of power control is required. the laser is optically coupled to a photo-diode, so that the laser?s optical output can be measured. laser optical output power is controlled by comparing the externally applied control voltage with the voltage produced by the iv-amplifier which converts the photo-diode?s output current into a voltage. since the calibrated gain is stored as a digital number in a register, the isl58125 exhibits none of the time-dependent droop that is seen in most printers' laser diode drivers. this is of particular importance during high dot/inch graphics modes where the line may be slowed down very significantly to allow 2400 dots per inch or even more. fixed-threshold laser bias control when a laser is driven from below threshold to well above threshold, it exhibits a few cycles of a damped oscillation. the amplitude of this oscillation is minimized when the laser is kept above threshold. the ?fixed? bias mode is set by asserting a logic low on the slpen pin. to set the laser bias threshold currents, i bias , connect external resistors from rbias pins to gnd. figure 1 shows value of r bias corresponding to desired bias current. scaling external resistors r set is used to scale the switching output current. switching output current, i sw , is the function of vc and r set where i sw gain = ~17, r dac = 400 . r bias sets bias threshold current. figure 1 exhibits the relationship between i bias and r bias . the bias current is set as equation 2: where biaschannelgain = ~40, internalvref = 1.0v. r ovr resistor defines the maximum current that can flow in either laser before the errb pin puts out a logical low. this can be used to detect fault conditions. since both channel?s overcurrent detectors are ored together, errb going low could indicate a fault in either or both output channels. note that the isl58125 does not shut itself down when an overcurrent condition is detected. the device controller is expected to take any required action. the maximum current is governed by equation 3: . controlling the sampling the switching levels are samp led independently. this can be done during the ?off-paper? period. during calibration mode, the internal servo control will bring the laser diode output power level to match the voltage control level set by vc voltage. typical application upon the printer being powered up, the lasers should be calibrated. this would establish nominal light power outputs, typically a few milliwatts at the laser regardless of the ambient temperature and also any laser aging. once everything is ready for printing, the paper is in position and the mirror-motor is phase-locked then the print line(s) can be written. before, or after, the beam is over the photo-sensitive drum, each laser can be re- calibrated. this continual re-calibration will compensate for any temperature drift of the laser, especially at the initial warming up period. since the calibrated gain is stored as a digital number in a register, the isl58125 exhibits no time-dependent droop. with no droop to degrade performance the only limitation now is the lasers' own temperature change along the line. this in turn can be compensated for to some extent by adding a data-dependent compensation signal to the analog vcx inpu t pin. it may be found that in fast draft modes for example, that the laser temperature change is sufficiently small that many lines can be written before the laser(s) need to be re- calibrated. if the printed page has a low enough duty cycle, no re-calibration may be needed at all. the isl58125 has analog voltage inputs to allow the laser power level to be adjust ed during the line. typically this would be driven with a pwm, low bandwidth signal to figure 1. r bias vs bias current 1 10 100 0.1 1 10 r bias (k ) i bias (ma) i sw i sw gain vc r dac --------------- - 2 r set --------------- ? ?? ?? = (eq. 1) i bias biaschannelgain internalvref r bias ----------------------------------- - = (eq. 2) i trip 1.05v r ovr 0.012 () ------------------------------------------ amp = (eq. 3) r ovr ( ) 5k 3k 80 60 40 20 0 100 2k 4k i trip (ma) 1k figure 2. r ovr vs i trip current isl58125
9 intersil products are manufactured, assembled and tested utilizing iso9000 qu ality systems as noted in the quality certifications found at www.intersil.com/design/quality intersil products are sold by description only. intersil corporation reserves the right to make changes in circuit design, soft ware and/or specifications at any time without notice. accordingly, th e reader is cautioned to verify that data sheets are current before placing orders. information furnished by intersil is believed to be accura te and reliable. however, no re sponsibility is assumed by inte rsil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which ma y result from its use. no licen se is granted by implication o r otherwise under any patent or patent rights of intersil or its subsidiaries. for information regarding intersil corporation and its products, see www.intersil.com fn6625.1 july 22, 2013 for additional products, see www.intersil.com/product_tree compensate for the differing beam path length as the beam is swept from one side of the page to the other. undervoltage, overcurrent and over-temperature error conditions are ored together and made available on the errb pin. power supply decoupling due to the high values of current being switched rapidly on and off, it is important to ensure that the power supply is well decoupled to ground. during switching, the v cc undergoes severe current transients, thus every effort should be made to decouple the v cc as close to the package as possible. symptoms that could arise include poor rise/fall times, current overshoot, and poor settling response. it is re comended that vcc inputs should be bypassed with 4.7f // 100nf // 470pf to gnd. inductance will be in series with the decoupling capacitor at the rate of about 0.6nh/mm of trace or capacitor distance. thus for a 3mm loop from v cc through the capacitor to ground, 300ma in 1ns will produce 540mv transient on the v cc -gnd voltage. isl58125
10 fn6625.1 july 22, 2013 about intersil intersil corporation is a leader in the design and manufacture of high-performance analog, mixed-signal and power management semiconductors. the company's products addr ess some of the largest markets within th e industrial and infr astructure, personal computing and high-end consumer markets. for more information about intersil, visit our website at www.intersil.com . for the most updated datasheet, application notes, related documentatio n and related parts, please see the respective product information page found at www.intersil.com . you may report errors or suggestions fo r improving this datasheet by visiting www.intersil.com/en/support/ask-an-expert.html . reliability reports are also available from our website at http://www.intersil.com/en/support/q ualandreliability.html#reliability revision history the revision history provided is for informat ional purposes only and is believed to be accurate, but not warranted. please go t o web to make sure you have the latest rev. date revision change 7/22/13 fn6625.1 updated datasheet by removing confidential watermark, changing logo, removed side bar with part number, copyright on page 1 and ch anged product informatio n verbiage to about intersil verbiage on page 14. 11/11/09 fn6625.0 initial release. isl58125
11 fn6625.1 july 22, 2013 isl58125 package outline drawing l28.4x5a 28 lead quad flat no-lead plastic package rev 2, 06/08 c 0 . 2 ref 0 . 05 max. 0 . 00 min. 5 4.00 a b 5.00 (4x) 0.15 6 pin 1 index area 23 pin #1 index area 28 2.50 24x 0.50 exp. dap 8 1 22 14 28x 0.400 9 6 3.50 max 0.90 see detail "x" seating plane 0.08 0.10 c c c ( 4.80 ) ( 3.50 ) ( 28 x 0.60) (28x .250) ( 24x 0.50) ( 3.80 ) ( 2.50) 2.50 0.10 28x 0.25 a mc b 4 3.50 exp. dap 15 typical recommended land pattern detail "x" top view bottom view side view side view located within the zone indicated. the pin #1 identifier may be unless otherwise specified, tolerance : decimal 0.05 tiebar shown (if present) is a non-functional feature. the configuration of the pin #1 identifier is optional, but must be between 0.15mm and 0.30mm from the terminal tip. dimension b applies to the metallized terminal and is measured dimensions in ( ) for reference only. dimensioning and tolerancing conform to amse y14.5m-1994. 6. either a mold or mark feature. 3. 5. 4. 2. dimensions are in millimeters. 1. notes:
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