DS3920 fast current mirror ????????????????????????????????????????????????????????????????? maxim integrated products 1 typical application circuit 19-5797; rev 0; 3/11 general description the DS3920 precision current mirror is designed for ava - lanche photodiode (apd) and pin photodiode biasing and monitoring applications. the device offers a current clamp to limit current through the apd and a current mir - ror output that produces a signal proportional (5:1) to the apd current. a diode is also provided to limit the voltage at the current mirror output. the device accepts a +2.97v to +76v current mirror supply voltage. internal current limiting (2.9ma or 20ma, typ) protects the monitored device from a short circuit to ground. the provided internal clamp diode protects the current mirror output from overvoltage. additionally, the device features thermal shutdown if the die temperature reaches +150 n c. the device is available in a 6-pin sot23 package, and operates over the -40 n c to +85 n c extended temperature range. features s wide voltage input range: 2.97v to 76v s current monitor ? wide 250na to 2ma range ? 5:1 mirror ratio ? fast 50ns time constant s current clamp (2.9ma or 20ma, typ) s voltage clamp protects subsequent output circuitry s 6-pin sot23 (max4007 compatible) applications avalanche photodiode (apd) biasing pin photodiode monitoring gepon, gpon, 10gepon, xgpon: onu and olt ordering information appears at end of data sheet. for related parts and recommended products to use with this part, refer to: www.maxim-ic.com/DS3920.related DS3920 i mirout i mirout /5 thermal shutdown current monitor current limit mirout mirin diode 3.3v apd bias mir i mirout /5 apd rosa gnd v out r agc 499 c filter 0.1 f r out r filter tia for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxims website at www.maxim-ic.com.
????????????????????????????????????????????????????????????????? maxim integrated products 2 DS3920 fast current mirror voltage range on mirin, mirout, and diode relative to gnd ............................ -0.3v to +80v voltage range on mir relative to gnd .............................. -0.3v to (v diode + 0.6v) continuous power dissipation (t a = +70 n c) sot23 (derate 13.4mw/ n c above +70 n c) ............. 1072.4mw operating junction temperature range ......... -40 n c to +150 n c storage temperature range ............................ -55 n c to +135 n c lead temperature (soldering, 10s) ................................ +300 n c soldering temperature (reflow) ...................................... +260 n c absolute maximum ratings stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. these are stress ratings only, and functional opera - tion of the device at these or any other conditions 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. note 1: see the typical application circuit . note 2: 1v dc change applied to mirin; 100 f a at mirout; 4.99k i load to ground on mir. note 3: guaranteed by design; not production tested. note 4: rising mirout transition from 10 f a to 1ma; 15v < v out < 76v. electrical characteristics (v mirin = 2.97v to 76v, t a = -40 n c to +85 n c, unless otherwise noted.) parameter symbol conditions min typ max units mirin voltage v mirin 2.97 76 v mirin current i mirin i mirout = 2.5ma 4.4 ma diode forward current i df 5 ma diode forward voltage v df i df = 100 f a, t a = +25 n c 0.6 v i df = 5ma, t a = +25 n c 1.25 mirout current limit i mirout DS3920t-001 version 10 20 40 ma DS3920t-002 version 2 2.9 4.4 mirout series resistance r agc (note 1) 100 w mir to mirout ratio k mir 1 f a to 2.5ma 0.190 0.200 0.210 a/a i mirout > 2.5ma 0.180 0.200 0.220 power-supply rejection ratio ( d i mir /i mir ) / d v mirin v mirin = 3v (note 2) 4800 15,000 ppm/v v mirin = 30v or 60v (notes 2, 3) 100 500 mir current rise time (20%/80%) t rc (note 4) 30 ns thermal shutdown temperature t shdn (note 3) +150 n c thermal shutdown hysteresis t hyst (note 3) 20 n c * the parametric values (min, typ, max limits) shown in the electrical characteristics table supersede values quoted elsewhere in this data sheet.
????????????????????????????????????????????????????????????????? maxim integrated products 3 DS3920 fast current mirror typical operating characteristics (t a = +25c, unless otherwise noted.) gain error vs. mirin voltage DS3920 toc06 v mirin (v) gain error (%) 60 40 20 -1.5 -1.0 -0.5 0 0.5 1.0 1.5 2.0 -2.0 0 80 i mirout = 2.5ma i mirout = 10ma i mirout = 1a i mirout = 5ma gain error vs. temperature DS3920 toc05 temperature (c) gain error (%) 60 35 10 -15 -4 -3 -2 -1 0 1 2 3 4 5 -5 -40 85 i mirout = 2.5ma i mirout = 10ma i mirout = 1a i mirout = 250a v mirin = 40v gain error vs. mirout current DS3920 toc04 i mirout (ma) gain error (%) 1 0.1 0.01 -4 -3 -2 -1 0 1 2 3 4 5 -5 0.001 10 v mirin = 40v mirin current vs. temperature DS3920 toc03 temperature (c) i mirin (ma) 60 35 10 -15 0.1 1 10 0.01 -40 85 i mirout = 2.5ma i mirout = 1a v mirin = 40v mirin current vs. mirout current DS3920 toc02 i mirout (ma) i mirin (ma) 1 0.1 0.01 0.1 1 10 100 0.01 0.001 10 v mirin = 40v mirin current vs. mirin voltage DS3920 toc01 v mirin (v) i mirin (ma) 60 40 20 0.1 1 10 0.01 0 80 i mirout = 2.5ma i mirout = 1a
????????????????????????????????????????????????????????????????? maxim integrated products 4 DS3920 fast current mirror typical operating characteristics (continued) (t a = +25c, unless otherwise noted.) startup delay (v mirin = 5v, i mirout = 2.5ma) DS3920 toc11 200s/div ch1 0v 0v ch1: 2v/div ch2: 2v/div ch2 d.u.t mirin mi r mirout ch2 ch1 5v r2 5k r1 1.7k startup delay (v mirin = 5v, i mirout = 1a) DS3920 toc10 200s/div ch1 0v 0v ch1: 2v/div ch2: 2v/div ch2 d.u.t mirin mir mirout ch2 ch1 5v r2 5k r1 4.6m startup delay (v mirin = 40v, i mirout = 2.5ma) DS3920 toc09 200s/div ch1 0v 0v ch1: 20v/div ch2: 20v/div ch2 d.u.t mirin mir mirout ch2 ch1 40v r2 5k r1 15.6k startup delay (v bias = 40v, i mirout = 1a) DS3920 toc08 200s/div ch1 0v 0v ch1: 20v/div ch2: 20v/div ch2 d.u.t mirin mir mirout ch2 ch1 40v r2 5k r1 38m transient response (v mirin = 40v) DS3920 toc07 500ns/div a a: ch1, 1v/div, i mirout = 375a to 7.5ma a: ch2; 5v/div, i mir = 75a to 1.5ma b d.u.t mirin mir mirout ch2 ch1 40v 5k 100k 5k
????????????????????????????????????????????????????????????????? maxim integrated products 5 DS3920 fast current mirror pin configuration pin description typical operating characteristics (continued) (t a = +25c, unless otherwise noted.) pin name function 1 diode protection diode. external potential used for voltage clamping of v mir . if unused, this pin can be left unconnected. 2 gnd ground 3 mir mirror current monitor output, 5:1 ratio 4 mirout current mirror voltage output. connect to photodiode bias pin. photodiode provides reference current for the mirror. 5 n.c. no connection. not internally connected. 6 mirin current voltage bias sot23 top view gnd mir 1 diode 2 3 mirout 6 mirin 5 n.c. + 4 DS3920 short-circuit response (v mirin = 40v) DS3920 toc12 20ms/div ch1 0a ch1: i mirout , 5ma/div a: mirout shorts to gnd through 10 b: current limit active c: thermal shutdown d: post cool-down reentry e: thermal shutdown f: post cool-down reentry t a = +40c a b c d e f short-circuit response (v mirin = 76v) DS3920 toc13 20ms/div ch1 0a ch1: i mirout , 5ma/div a: mirout shorts to gnd through 10 b: current limit active c: thermal shutdown d: post cool-down reentry e: thermal shutdown f: post cool-down reentry t a = +40c a b c d e f voltage drop vs. mirout current DS3920 toc14 i mirout (ma) v mirin - v mirout (v) 10 1 0.1 0.01 0.2 0.4 0.6 0.8 1.0 1.2 1.4 0 0.001 100 v mirin = 2.97v t a = -40c t a = +25c t a = +100c t a = +85c
????????????????????????????????????????????????????????????????? maxim integrated products 6 DS3920 fast current mirror detailed description the DS3920 provides a fast, precision current mirror for photodiode-monitoring applications. the current mirror is accurate across a large dynamic range. the mirror response time is fast enough to comply with gpon rx burst-mode monitoring requirements. the device has a built-in current limiting feature to protect photodiodes from large signal inputs, and an included thermal shut - down. a diode is provided to limit the voltage at the mir output. current mirror the mirror output is typically connected to an analog- to-digital converter (adc) using a resistor to convert the mirrored current into a voltage. the resistor to ground should be selected so that the adcs full-scale voltage is reached when the maximum mirrored current is reached. for example, given that the maximum monitored current through the apd is 2ma, 1.25v adc full scale, and a 5:1 mirror ratio, the correct resistor is approximately 3.2k i . the mirror response time is dominated by the amount of capacitance placed on the output. current clamp the device features a current clamping circuit to protect the photodiode by limiting the amount of current from mirout to no more than i mirout . see the ordering information for available current clamp options. diode protection a diode is internally connected from the mir to diode pins. this enables an external voltage applied to diode to limit the voltage on mir. the voltage applied to diode should be equal to the desired v mir limit minus the diode forward voltage drop, or v mir - v df . thermal shutdown as a safety feature, the device has a thermal shutdown circuit that turns off the mirout and mir currents when the internal die temperature exceeds t shdn . the thermal shutdown mechanism has a built-in hysteresis of t hyst . thus, the mirout and mir currents resume once the device has cooled to t shdn - t hyst . ordering information + denotes a lead(pb)-free/rohs-compliant package. t = tape and reel. package information for the latest package outline information and land patterns (footprints), go to www.maxim-ic.com/packages . note that a +, #, or - in the package code indicates rohs status only. package drawings may show a different suffix character, but the drawing pertains to the package regardless of rohs status. part temp range typ current limit (ma) pin-package DS3920t-001+ -40 n c to +85 n c 20 6 sot23 DS3920t-001+t -40 n c to +85 n c 20 6 sot23 DS3920t-002+ -40 n c to +85 n c 2.9 6 sot23 DS3920t-002+t -40 n c to +85 n c 2.9 6 sot23 package type package code outline no. land pattern no. 6 sot23 u6sn+1 21-0058 90-0175
maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circuit patent licenses are implied. maxim reserves the right to change the circuitry and specifications without notice at any time. maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 7 ? 2011 maxim integrated products maxim is a registered trademark of maxim integrated products, inc. DS3920 fast current mirror revision history revision number revision date description pages changed 0 3/11 initial release
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