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ht70xx voltage detector selection table part no. detectable voltage hysteresis width tolerance ht7024a 2.4v 0.12v 5% ht7027a 2.7v 0.135v 5% ht7033a 3.3v 0.165v 5% ht7039a 3.9v 0.195v 5% ht7044a 4.4v 0.22v 5% ht7050a 5v 0.25v 5% ht7070a 7v 0.35v 5% note: the output type selection codes are: nmos open drain normal open, active low pmos open drain normal open, active high for example: the ht7070a is a 7v, nmos open drain active low output 1 may 3, 2000 general description the ht70xx series is a set of three-terminal low power voltage detectors implemented in cmos technology. each voltage detector in the series detects a particular fixed voltage ranging from 2.4v to 7v. the voltage detectors consist of a high-precision and low power consumption standard voltage source, a comparator, hyster - esis circuit, and an output driver. cmos tech - nology ensures low power consumption. although designed primarily as fixed voltage detectors, these devices can be used with exter - nal components to detect user specified thresh - old voltages (nmos open drain type only). features low power consumption low temperature coefficient built-in high-stability reference source built-in hysteresis characteristic to-92 & sot-89 package applications battery checkers level selectors power failure detectors microcomputer reset battery memory backup non-volatile ram signal storage protectors
output type selection table v dd v dd v det (+) v dd v det ( ) type v out a hi-z vss block diagram n channel open drain output (normal open; active low) a type ht70xx 2 may 3, 2000 gnd vout vdd v ref v out v in v det v hys pin assignment pad assignment chip size: 1317 1158 ( m) 2 * the ic substrate should be connected to vdd in the pcb layout artwork. pad coordinates unit: m pad no. x y 1 483.30 379.50 2 234.60 399.50 3 443.90 386.00 absolute maximum ratings supply voltage............................... 0.3v to 26v output current .........................................50ma output voltage ..............v ss 0.3v to v dd +0.3v storage temperature................. 50 cto125 c power consumption...............................200mw operating temperature ..................0 cto70 c note: these are stress ratings only. stresses exceeding the range specified under absolute maxi- mum ratings may cause substantial damage to the device. functional operation of this de- vice at other conditions beyond those listed in the specification is not implied and prolonged exposure to extreme conditions may affect device reliability. ht70xx 3 may 3, 2000 electrical characteristics ht7024a ta=25 c symbol parameter test conditions min. typ. max. unit v dd conditions v det hi lo detectable voltage 2.28 2.4 2.52 v lo hi detectable voltage 2.325 2.52 2.772 v v hys hysteresis width 0.02 v det 0.05 v det 0.1 v det v i dd operating current 8 no load 47 a v dd operating voltage 1.5 24 v i ol output sink current 2 v out =0.2v 0.5 1 ma v t det a temperature coefficient 0 c v t det a temperature coefficient 0 c v t det a temperature coefficient 0 c v t det a temperature coefficient 0 c v t det a temperature coefficient 0 c v t det a temperature coefficient 0 c v t det a temperature coefficient 0 c ht70xx 8 may 3, 2000 application circuits microcomputer reset circuit normally a reset circuit is required to protect the microcomputer system from malfunctions due to power line interruptions. the following examples show how different output configura - tions perform a reset function in various sys - tems. nmos open drain output application for separate power supply nmos open drain output application with r-c delay power-on reset circuit with several external components, the nmos open drain type of the ht70xx series can be used to perform a power-on reset function as shown: ht7044a v out v ss r d v in v dd c t v dd t v out v out v ss v dd2 v dd1 reset ht70xxa v ss v out micro - computer ht70xxa v dd v ss v out micro - computer c r ht70xx 9 may 3, 2000 5v power line monitoring circuit generally, a minimum operating voltage of 4.5v is guaranteed in a 5v power line system. the ht7044a is recommended for use as 5v power line monitoring circuit. 5v power line monitor with power-on reset with 5v voltage regulator change of detectable voltage if the required voltage is not found in the stan - dard product selection table, it is possible to change it by using external resistance dividers or diodes. varying the detectable voltage with a resis - tance divider detectable voltage = ra rb rb v det hysteresis width = ra rb rb v hys varying the detectable voltage with a diode detectable voltage = v f1 +v f2 +v det ht7044a v ss v dd v ss c v out 5v power line d r ht7044a v ss v dd ht1050 v out v in gnd 5v 5v voltage regulator ht70xxa v dd v in v ss vf1 vf2 v out v ss ht70xxa v ss v in v ss ra rb v out v dd level selector the following diagram illustrates a logic level selector. ht70xx 10 may 3, 2000 malfunction analysis the following circuit demonstrates the way a circuit analyzes malfunctions by monitoring the variation or spike noise of power supply voltage. charge monitoring circuit the following circuit shows a charged monitor for protection against battery deterioration by overcharging. when the voltage of the battery is higher than the set detectable voltage, the transistor turns on to bypass the charge cur - rent, protecting the battery from overcharging. v dd ht7039a v out ht7050a v out v ss v out v det1 v det2 v dd v det1 v det2 v out t t 5.0v 3.9v ht70xxa v out v ss v dd v ss ht70xxa v dd v out v ss load batt solar cell tr ht70xx 11 may 3, 2000 copyright 2000 by holtek semiconductor inc. the information appearing in this data sheet is believed to be accurate at the time of publication. however, holtek assumes no responsibility arising from the use of the specifications described. the applications mentioned herein are used solely for the purpose of illustration and holtek makes no warranty or representation that such applications will be suitable without further modification, nor recommends the use of its products for application that may pres - ent a risk to human life due to malfunction or otherwise. holtek reserves the right to alter its products without prior notification. for the most up-to-date information, please visit our web site at http://www.holtek.com.tw. holtek semiconductor inc. (headquarters) no.3 creation rd. ii, science-based industrial park, hsinchu, taiwan, r.o.c. tel: 886-3-563-1999 fax: 886-3-563-1189 holtek semiconductor inc. (taipei office) 5f, no.576, sec.7 chung hsiao e. rd., taipei, taiwan, r.o.c. tel: 886-2-2782-9635 fax: 886-2-2782-9636 fax: 886-2-2782-7128 (international sales hotline) holtek semiconductor (hong kong) ltd. rm.711, tower 2, cheung sha wan plaza, 833 cheung sha wan rd., kowloon, hong kong tel: 852-2-745-8288 fax: 852-2-742-8657 |
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