AS1907, as1908, as1909 low-voltage microprocessor reset circuits www.austriamicrosystems.com revision 1.05 1 - 10 data sheet 1 general description the AS1907/as1908/as1909 microprocessor supervi- sory circuits are ideal for monitoring the supply voltage of digital systems and microprocessors. the devices are designed to initiate a reset if the supply voltage goes below a predefined threshold. the duration of the reset is either 1.5, 30, or 150ms (typ.) after the supply voltage has risen above the pre-set threshold (see ordering information on page 9) . the devices are available as the standard products listed in ta b l e 1 . the reset thresholds are factory-set between 1.6 and 2.5v in steps of approximately 100mv (see table 5 on page 7) . the devices exhibit excellent reliability, and can reduce system costs by eliminating the need for external com- ponents. the extremely low current consumption makes the devices ideal for use in portable applications. the integrated reset comparator was specifically designed to ignore fast transients on v cc . the devices are available in a 3-pin sot23 package. figure 1. application diagrams 2 key features 3 output types: push/p ull reset, push pull resetn, and open drain resetn reset threshold range: 1.6 to 2.5v (~100mv incre- ments) reset/resetn: - valid to v cc = 0.7v (AS1907 and as1908) - valid to v cc = 1.0v (as1909) reset pulse widths: 1, 20, and 100ms supply voltage range: +0.7 to +3.6v supply current range: 2.6 to 7.0a power supply transient immunity requires no external components operating temperature range: -40 to +125oc 3-pin sot23 package 3 applications the devices are ideal for use in cordless and mobile phones, mp3 players, cd and dvd players, pdas, handheld computers, digital cameras, hard drives, and any other application where power supply supervisory control is required. table 1. standard products model output type reset type AS1907 push/pull active-low as1908 push/pull active-high as1909 open-drain active-low 2 reset as1908 micro- processor v cc v cc gnd 1 v cc 3 v cc 3 reset i/o resetn 2 AS1907 gnd 1 v cc 3 gnd 1 micro- processor v cc 3 reset i/o gnd 1 2 resetn as1909 micro- processor v cc gnd 1 v cc 3 v cc 3 reset i/o gnd 1
www.austriamicrosystems.com revision 1.05 2 - 10 AS1907/as1908/as1909 data sheet - pinout 4 pinout pin assignments figure 2. pin assignments (top view) pin descriptions table 2. pin descriptions pin number pin name description 1gnd ground 2 reset active-high reset output (as1908). this pin stays high whenever v cc is below the reset threshold v th (see page 7) , and for t tp (see page 4) after v cc rises above v th . resetn active-low reset output (AS1907, as1909). this pin remains low while v cc is below the reset threshold v th (see page 7) , and for t tp (see page 4) after v cc rises above v th . note: this pin is open-drain on the as1909. 3v cc positive supply voltage . connect to +0.7 to +3.6v supply. 1 as1908/ AS1907/ as1909 gnd 2 reset, resetn 3v cc
www.austriamicrosystems.com revision 1.05 3 - 10 AS1907/as1908/as1909 data sheet - absolute maximum ratings 5 absolute maximum ratings stresses beyond those listed in table 3 may cause permanent damage to the device. these are stress ratings only, and functional operation of the de vice at these or any other cond itions beyond those indicated in section 6 electrical characteristics on page 4 is not implied. exposure to absolute maxi mum rating conditions for extended periods may affect device reliability. table 3. absolute maximum ratings parameter min max units comments v cc -0.3 +5 v reset, resetn push/pull -0.3 v cc + 0.3 v resetn open drain -0.3 +6 v input current (v cc ) 20 ma output current (reset, resetn) 20 ma continuous power dissipation (t amb = +70oc) 320 mw 3-pin sot23 derate 4mw/oc above +70oc operating temperature range -40 +125 oc storage temperature range -65 +160 oc package body temperature +260 oc the reflow peak soldering temperature (body temperature) specified is in accordance with ipc/jedec j-std-020c ?moisture/reflow sensitivity classification for non-hermetic solid state surface mount devices?
www.austriamicrosystems.com revision 1.05 4 - 10 AS1907/as1908/as1909 data sheet - electrical characteristics 6 electrical characteristics v cc = full range, t amb = -40 to +125oc (unless otherwise specified). typ values are at v cc = +3.0v, t amb = +25oc. table 4. electrical characteristics parameter symbol conditions min typ max unit supply voltage range v cc t amb = 0 to +85oc AS1907, as1908 0.7 3.6 v as1909 1.0 3.6 t amb = -40 to +85oc AS1907, as1908 0.78 3.6 as1909 1.2 3.6 t amb = -40 to +125oc 1.2 3.6 supply current 1 1. not valid if v cc = v th . i cc v cc = 1.8v, no load 2.4 6.0 a v cc = 2.5v, no load 2.6 7.0 reset threshold voltage v th t amb = +25oc v th - 0.9% v th v th + 0.9% v t amb = 0oc to +50c; as1909c17 and as1909c168 only v th - 1.2% v th v th + 1.2% v t amb = -40 to +125oc v th - 3% v th v th + 3% v v cc falling reset delay t rd v cc falling at 10v/ms 33 s reset active time-out period t tp as190x-azz-t 1 1.5 2 ms as190x-bzz-t 20 30 40 as190x-czz-t 100 150 200 resetn output low voltage; reset asserted (AS1907/as1909) v ol i sink = 50a, v cc 1.0v 0.4 v i sink = 500a, v cc 1.8v 0.3 resetn output high voltage; reset not asserted (AS1907) v oh i source = 200a, v cc 1.8v 0.8 x v cc v i source = 500a, v cc 2.7v 0.8 x v cc reset output vo ltage; reset asserted (as1908) v oh i source = 1a, v cc 1.0v 0.8 x v cc v i source = 200a, v cc 1.8v 0.8 x v cc reset output vo ltage; reset not asserted (as1908) v ol i sink = 500a, v cc 1.8v 0.3 v i sink = 1.2ma, v cc 2.7v 0.3 resetn output leakage current; resetn deasserted (as1909) i leak v cc > v th 0.5 a
www.austriamicrosystems.com revision 1.05 5 - 10 AS1907/as1908/as1909 data sheet - typical operating characteristics 7 typical operating characteristics t amb = +25oc (unless otherwise specified). figure 3. supply current vs. temperature figure 4. supply current vs. supply voltage figure 5. normalized reset timeout period vs. figure 6. output voltage low vs. temperature temperature, v th = 2.3v reset asserted figure 7. max. transient duration vs. figure 8. v cc falling propagation delay vs. reset comparator ov erdrive temperature 0 1 2 3 4 5 6 1.4 1.8 2.2 2.6 3 3.4 3.8 supply voltage (v) supply current (a) . 2 2.2 2.4 2.6 2.8 3 3.2 -50 -25 0 25 50 75 100 125 temperature (c) supply current (a) . v cc = 2.5v v cc = 1.8v 5 15 25 35 45 55 65 75 -50 -25 0 25 50 75 100 125 temperature (c) output voltage low (mv) . v cc = 1.8v i sink = 500a v cc = 2.2v i sink = 500a v cc = 0.7v i sink = 50a v cc = 1.0v i sink = 50a 0.9 1 1.1 1.2 1.3 -50 -25 0 25 50 75 100 125 temperature (c) norm. reset timeout period . 0 20 40 60 80 100 120 140 -50 -25 0 25 50 75 100 125 temperature (c) propagation delay (s) . 0 100 200 300 400 500 600 700 0.1 1 10 100 1000 reset comparator overdrive (mv) max. transient duration (s) . reset occurs reset does not occur v cc falling at 1v/ms v cc falling at 10v/ms
www.austriamicrosystems.com revision 1.05 6 - 10 AS1907/as1908/as1909 data sheet - typical operating characteristics figure 9. output voltage low vs. v cc , i sink = 50a figure 10. output voltage low vs. v cc , i sink = 100a figure 11. output voltage low vs. v cc , i sink = 500a 0 10 20 30 40 50 60 0.7 1 1.3 1.6 1.9 2.2 v cc (v) output voltage low (mv) . temp = -40c temp = +25c temp = +85c temp = +125c 0 10 20 30 40 50 60 70 80 0.7 1 1.3 1.6 1.9 2.2 v cc (v) output voltage low (mv) . temp = -40c temp = +25c temp = +85c temp = +125c 0 50 100 150 200 250 0.7 1 1.3 1.6 1.9 2.2 v cc (v) output voltage low (mv) . temp = -40c temp = +25c temp = +85c temp = +125c
www.austriamicrosystems.com revision 1.05 7 - 10 AS1907/as1908/as1909 data sheet - application information 8 application information negative going v cc transients all devices are effectively immune to short-duration, negative-going v cc transients (glitches). the maximum transient duration vs. reset comparator overdrive graph (see page 5) shows the maximum pulse width that a negative-going v cc transient may typically have without issuing a reset signal . as the amplitude of the tr ansient increases, the maxi- mum allowable pulse width decreases. valid reset output if v cc falls below 1v and approaches the minimum operating volt age of 0.7v, push/pull-type reset sinking/sourcing capabilities greatly decrease. high-imp edance cmos-logic inputs connected to r eset can drift to indeterminate volt- ages, although this is normally not a problem since most microprocessors do not operate at v cc < 1v. for the as1908, where reset must be valid to v cc = 0, a 100k pull-up resistor between reset and v cc (see fig- ure 1 on page 1) will hold reset high if v cc falls below 0.7v. for the AS1907, where reset must be valid down to 0v, add a pull-dow n resistor betwe en reset and gnd (see figure 1 on page 1) to eliminate stray leakage currents and hold reset low. a pull-down resistor of 100k is large enough not to load reset yet small enough to pull it low. since the as1909 has an open-drain, active-low output, it typi cally uses a pull-up resistor. with this device, reset will most likely not maintain an active condition, but will drif t to a non-active level due to the pull-up resistor and the reduced sinking capability of the open drain device. therefor e, this device is not recommended for applications where the reset pin is required to be valid down to v cc = 0. bi-directional microprocessor interface the reset output on the as1909 is open-d rain, thus this device can interface easily with microprocessors that have bi-directional reset pins, such as the motorola 68hc11. connect the reset output of this device directly to the micr oprocessor?s reset i/o pin with a single pull-up resistor to allow either device to assert reset (see figure 1 on page 1) . layout considerations the devices require proper layout and de sign procedures for optimum performance. short, wide traces should be used to reduce stray inductance and capacitance. bypass capacitors should be as close to the device as possible. large ground planes should be used wherever possible. table 5. reset thresholds reset thresholds t amb = +25oc t amb = -40 to +125oc suffix min typ max min max 25 2.478 2.50 2.523 2.43 2.58 24 2.378 2.40 2.422 2.33 2.47 23 2.279 2.30 2.321 2.23 2.37 22 2.180 2.20 2.220 2.13 2.27 21 2.081 2.10 2.119 2.04 2.18 20 1.982 2.00 2.018 1.94 2.06 19 1.883 1.90 1.917 1.84 1.96 18 1.784 1.80 1.816 1.75 1.85 17 1.685 1.70 1.715 1.65 1.75 16 1.586 1.60 1.614 1.55 1.65
www.austriamicrosystems.com revision 1.05 8 - 10 AS1907/as1908/as1909 data sheet - pack age drawings and markings 9 package drawings and markings the devices are available in an 3-pin sot23 package. figure 12. 3-pin sot23 package notes: 1. dimensions d and e do not include mold flash. 2. mold flash protrusions not to exceed .15mm (.006?). 3. controlling dimension: millimeter. symbol min max a 0.787 1.194 a1 0.025 0.127 b 0.356 0.559 c 0.086 0.152 d 2.667 3.048 e 1.194 1.397 e 1.778 2.032 h 2.083 2.489 l 0.102 0.305 s 0.432 0.559 0o 8o
www.austriamicrosystems.com revision 1.05 9 - 10 AS1907/as1908/as1909 data sheet - ordering information 10 ordering information the devices are available as the following standard products. non-standard versions require a minimum order of 30,000 units. contact austriamicrosystems, ag for availability of non-standard versions. all devices are rohs compliant and free of halogene substances. * these devices are available in factory-set v cc reset thresholds from 1.6v to 2.5v, in approximately 100mv incre- ments. choose the desired re set threshold suffix from (see table 5 on page 7) and insert it instead of ?yy? in the part number. factory-programmed reset timeout periods are also available. insert the code corresponding to the desired nominal reset timeout period (see table 7) instead of ?x? in the part number. all devices available in tape-and-reel only. table 6. ordering information type marking reset type reset threshold minimum reset timeout delivery form as1908c18-t ashu active high 1.8v 100ms tape and reel as1908c20-t ashv active high 2.0v 100ms tape and reel AS1907c16-t ashp active low 1.6v 100ms tape and reel AS1907c18-t ashq active low 1.8v 100ms tape and reel AS1907c20-t ashr active low 2.0v 100ms tape and reel AS1907c22-t asnb active low 2.2v 100ms tape and reel AS1907b23-t ashx active low 2.3v 20ms tape and reel as1909c16-t ashy open drain 1.6v 100ms tape and reel as1909c168-t assb open drain 1.68v 100ms tape and reel as1909c17-t ashz open drain 1.7v 100ms tape and reel as1909c18-t asnd open drain 1.8v 100ms tape and reel as1909c20-t ash1 open drain 2.0v 100ms tape and reel as1909c22-t asnc open drain 2.2v 100ms tape and reel as1909c23-t ash2 open drain 2.3v 100ms tape and reel table 7. coding of factory-trimmed reset active time-out period device suffix t tp in milliseconds min typ max AS1907xyy-t* as1908xyy-t* as1909xyy-t* a11.52 b203040 c 100 150 200
www.austriamicrosystems.com revision 1.05 10 - 10 AS1907/as1908/as1909 data sheet copyrights copyright ? 1997-200 9, austriamicrosystems ag, schloss premstaett en, 8141 unterpremstae tten, austria-europe. trademarks registered ?. all rights reserved. the materi al herein may not be reprodu ced, adapted, merged, trans- lated, stored, or used witho ut the prior written consent of the copyright owner. all products and companies mentioned are trademarks or registered trademarks of their respective companies. disclaimer devices sold by austriamicrosystems ag are covered by t he warranty and patent indemni fication provisions appearing in its term of sale. austriamicrosystems ag makes no warranty, express, statutory, implied, or by description regarding the information set forth herein or regarding the freedom of the described devices from patent infringement. austria- microsystems ag reserves the right to change specifications and prices at any time and without notice. therefore, prior to designing this product into a syst em, it is necessary to check with aust riamicrosystems ag for current informa- tion. this product is intended for use in normal commercial applications. applications requiring extend ed temperature range, unusual environmental requirements, or high reliability app lications, such as military, medical life-support or life- sustaining equipment are specifically not recommended wit hout additional processing by austriamicrosystems ag for each application. for shipments of less than 100 parts the m anufacturing flow might show deviations from the standard production flow, such as test flow or test location. the information furnished here by austriamicrosystems ag is believed to be correct and accurate. however, austriamicrosystems ag shall not be liable to recipient or any third party for any damages, including but not limited to personal injury, property damage, loss of profits, loss of use, interruption of business or indirect, special, incidental or consequential damages, of any kind, in connection with or ar ising out of the furnishing, performance or use of the tech- nical data herein. no obligation or liability to recipient or any third party shall arise or flow out of austriamicrosystems ag rendering of technical or other services. contact information headquarters austriamicrosystems ag a-8141 schloss premstaetten, austria tel: +43 (0) 3136 500 0 fax: +43 (0) 3136 525 01 for sales offices, distributors and representatives, please visit: http://www.austriamicr osystems.com/contact-us
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