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| HT70XX Voltage Detector 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 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, hysteresis circuit, and an output driver. CMOS technology ensures low power consumption. Although designed primarily as fixed voltage detectors, these devices can be used with external components to detect user specified threshold voltages (NMOS open drain type only). Selection Table Part No. HT7024A HT7027A HT7033A HT7039A HT7044A HT7050A HT7070A Detectable Voltage 2.4V 2.7V 3.3V 3.9V 4.4V 5V 7V Hysteresis Width 0.12V 0.135V 0.165V 0.195V 0.22V 0.25V 0.35V Tolerance 5% 5% 5% 5% 5% 5% 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 HT70XX Output type selection table VDD Type VOUT A VDD>VDET(+) Hi-Z VDDVDET(-) VSS Block Diagram N channel open drain output (normal open; active low) VDD VOUT VREF GND A type VOUT VDET VHYS VIN 2 May 3, 2000 HT70XX Pin Assignment T O -9 2 H T70XX F r o n t V ie w Pad Assignment S O T -8 9 (0 ,0 ) 1 2 VOUT 3 GND V IN OUTVDD VSS B o tto m V ie w OUT VDD VSS Chip size: 1317 1158 (mm) 2 * The IC substrate should be connected to VDD in the PCB layout artwork. Pad Coordinates Pad No. 1 2 3 X -483.30 -234.60 443.90 Y Unit: mm -379.50 -399.50 -386.00 Absolute Maximum Ratings Supply Voltage...............................-0.3V to 26V Output Voltage ..............VSS-0.3V to VDD+0.3V Power Consumption...............................200mW Output Current .........................................50mA Storage Temperature.................-50C to 125C Operating Temperature ..................0C to 70C Note: These are stress ratings only. Stresses exceeding the range specified under Absolute Maximum Ratings may cause substantial damage to the device. Functional operation of this device at other conditions beyond those listed in the specification is not implied and prolonged exposure to extreme conditions may affect device reliability. 3 May 3, 2000 HT70XX Electrical Characteristics HT7024A Symbol VDET VHYS IDD VDD IOL DVDET DTA HT7027A Symbol VDET VHYS IDD VDD IOL DVDET DTA Parameter Hi(R)Lo Detectable Voltage Lo(R)Hi Detectable Voltage Hysteresis Width Operating Current Operating Voltage Output Sink Current Temperature Coefficient Test Conditions VDD 3/4 3/4 3/4 8 3/4 2 3/4 Conditions 3/4 3/4 3/4 No load 3/4 VOUT=0.2V 0C May 3, 2000 HT70XX HT7033A Symbol VDET VHYS IDD VDD IOL DVDET DTA HT7039A Symbol VDET VHYS IDD VDD IOL DVDET DTA Parameter Hi(R)Lo Detectable Voltage Lo(R)Hi Detectable Voltage Hysteresis Width Operating Current Operating Voltage Output Sink Current Temperature Coefficient Test Conditions VDD 3/4 3/4 3/4 8 3/4 2.5 3/4 Conditions 3/4 3/4 3/4 No load 3/4 VOUT=0.25V 0C May 3, 2000 HT70XX HT7044A Symbol VDET VHYS IDD VDD IOL DVDET DTA HT7050A Symbol VDET VHYS IDD VDD IOL DVDET DTA Parameter Hi(R)Lo Detectable Voltage Lo(R)Hi Detectable Voltage Hysteresis Width Operating Current Operating Voltage Output Sink Current Temperature Coefficient Test Conditions VDD 3/4 3/4 3/4 8 3/4 3.6 3/4 Conditions 3/4 3/4 3/4 No load 3/4 VOUT=0.36V 0C May 3, 2000 HT70XX HT7070A Symbol VDET VHYS IDD VDD IOL DVDET DTA Parameter Hi(R)Lo Detectable Voltage Lo(R)Hi Detectable Voltage Hysteresis Width Operating Current Operating Voltage Output Sink Current Temperature Coefficient Test Conditions VDD 3/4 3/4 3/4 8 3/4 5 3/4 Conditions 3/4 3/4 3/4 No load 3/4 VOUT=0.5V 0C The HT70XX series is a set of voltage detectors equipped with a high stability voltage reference which is connected to the negative input of a comparator3/4 denoted as VREF in the following figure for NMOS output voltage detector. When the voltage drop to the positive input of the comparator (i,e,VB) is higher than VREF, VOUT goes high, M1 turns off, and VB is expressed as VBH=VDD(RB+RC)/(RA+RB+RC). If VDD is decreased so that VB falls to a value less than VREF, the comparator output inverts from high to low, VOUT goes low, VC is high, M1 turns on, RC is bypassed, and VB becomes: VBL=VDDRB/(RA+RB), which is less than VBH. By so doing, the comparator output will stay low to prevent the circuit from oscillating when VB VREF. If VDD falls below the minimum operating voltage, the output becomes undefined. When VDD goes from low to VDDRB/(RA+RB) > VREF, the comparator output and VOUT goes high. V The hysteresis width is: VHYS = VDET (+) - VDET (-) The figure demonstrates the NMOS output type with positive output polarity (VOUT is normally open, active low). The HT70XX series also supplies options for other output types with active high outputs. Application circuits shown are examples of positive output polarity (normally open, active low) unless otherwise specified. V DD RA C o m p a ra to r V B RL V C V MN OUT REF RB M1 RC The detectable voltage is defined as: RA + RB + RC VDET (-) = VREF RB + RC The release voltage is defined as: RA + RB VDET (+) = VREF RB 7 V SS NMOS output voltage detector (HT70XXA) May 3, 2000 HT70XX 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 configurations perform a reset function in various systems. * NMOS open drain output application for 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: VIN R D separate power supply VDD1 VOUT VDD2 VDD C VOUT VOUT HT70XXA RESET Micro computer HT7044A VSS VDD VSS VSS * NMOS open drain output application with R-C delay VDD R t VOUT HT70XXA VOUT Micro computer C VSS t 8 May 3, 2000 HT70XX 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 5V Power line R D RA VDD VOUT Change of detectable voltage If the required voltage is not found in the standard 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 VIN VDD C VOUT RB VSS HT70XXA VSS HT7044A VSS VSS Detectable * with 5V voltage regulator 5V Voltage regulator VIN Hysteresis RA + RB VDET RB RA + RB width = VHYS RB voltage = * Varying the detectable voltage with a diode VIN Vf1 HT1050 GND 5V VDD VOUT Vf2 VDD VOUT HT7044A VSS VSS HT70XXA VSS Detectable Voltage = Vf1+Vf2+VDET 9 May 3, 2000 HT70XX Malfunction analysis The following circuit demonstrates the way a circuit analyzes malfunctions by monitoring the variation or spike noise of power supply voltage. VDD VOUT 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 current, protecting the battery from overcharging. VDD Solar Cell VOUT Tr BATT Load HT70XXA VSS VSS VSS HT70XXA Level selector The following diagram illustrates a logic level selector. VDD VOUT VOUT VOUT HT7039A VSS VDD VDET2 HT7050A VDET1 5.0V VDET1 3.9V VDET2 VOUT t t 10 May 3, 2000 HT70XX 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 Copyright O 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 present 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. 11 May 3, 2000 |
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