AMIS-70020 Power Failure Elapsed Time Counter Data Sheet 1.0 General Description The few external components required to build the AMIS70020 into its application result in a cost effective solution and in a footprint of less than 2cm2. The combination of an internal oscillator and a microcontroller software algorithm eliminate the requirement for a space and cost consuming external crystal. The AMIS-70020 is a timer IC that measures the duration of power failures of up to five hours. The AMIS-70020 starts and stops counting automatically as it is triggered by the voltage of the input signal VCC. When VCC gets lower than the reference signal VDD - VTH, a power cut-off is flagged and the AMIS-70020 starts counting. During the counting phase the AMIS-70020 is powered by an external capacitor or by a primary battery and consequently operates independently of an external power supply. Due to the low power design of the AMIS-70020, the device can count the full scale autonomously using the energy stored in a 10mF capacitor. Typical applications are those sensitive to power failures that do not have a built-in UPS function. Examples are: • Power inverters/Motordrivers/Soft starters • Accurate I2t protection possible even after power loss • Thermal protection devices for electrical motors without integrated thermistor • Motor controllers for electrical motors without integrated thermistor • Process control • Chemical processes • Industrial mixers • Mixing reactors As soon as VCC comes up again counting stops. The value of the counter is shifted to the digital Q_OUT output pin and is communicated to a microprocessor. After shifting the full counted value, the internal RC-oscillator signal is put on the Q_OUT output pin. Using this data the microcontroller can calculate the duration of the power failure. The internal power management circuit manages the recharge of the external buffer capacitor. 2.0 Key Features • Built-in 1kHz oscillator • No external oscillator required • Frequency of oscillator can be read by an external microcontroller • Accurate time measurement possible using software calibration algorithm • 2-wire interface with standard I/O pins of a microcontroller • Operating temperature -10~85˚C • 150 mils SO8 package • Few external components • Easy design-in due to a user friendly application board • Measures the time elapsed during a power failure • Measures up to five hours • 1 second resolution (RC oscillator/1024) • Autonomous operation during power failure • Auto switching to backup power • Auto counter-start/stop function • Maintenance free buffer capacitor - 6 hours back-up with 10mF - Capacitor recharge management built in (no external diode needed) • Li-button cell - CR1220 (35mAh) supports up to 10 years in a typical application • Low current consumption <1µA 3.0 Ordering Information Ordering Code Package Temp. Range AMIS-70020 SO8 -10°C…-85°C Ordering Code EVK-70020 Evaluation kit For sample requests contact your local sales representative at www.amis.com/sales. AMI Semiconductor www.amis.com 1 AMIS-70020 Power Failure Elapsed Time Counter Data Sheet 4.0 Block Diagram CUT_OFF Test VCC 1 0 m3 1 CUT_OFF 8 Test_Detect CUT_OFF Switch 3 COMPARATOR VDD 2 POR OUT_PORB CUT_OFF_CMD C CONTROL Oscillator CLK_1K 1 kHz 0 Divider (10 bits) m1 1 0 m2 1 0 m0 Q14_OUT 1 Register/Counter (15 bits) Q_OUT 5 EN0 Uc_Clk UC_CLK_IN Current_source 6 CLK_1S 7 Clk 4 VSS 5.0 Packaging The AMIS-70020 is packaged in a 150mils SO8. Please visit http://www.amis.com/pdf/soic.pdf for detailed mechanical information. Pinout 8 1 VCC Uc_Clk 5 4 VSS Clk 6 3 Test_Out CUT_OFF AMIS70020 7 2 VDD Test Q_Out Pad Description Pad No. 1 2 3 4 5 6 Name VCC VDD CUT_OFF VSS Q_OUT Uc_Clk Type Power Power Digital Output Power Digital Output Digital Input 7 8 Clk Test Digital Output Digital Input AMI Semiconductor www.amis.com Comment System power that is monitored Back-up power Not connected, test purpose only Ground Shift register output (CMOS output buffer 2mA) CLK from microcontroller (Schmitt trigger input); an internal pull down (100KΩ) is connected on the pin Internal oscillator/1024 (1Hz) (CMOS output buffer 2mA) For normal operation: connect to GND 2 AMIS-70020 Power Failure Elapsed Time Counter Data Sheet 6.0 Application Diagram Supply 5V 100nF 8 1 VCC Test 7 2 10 mF VDD MICRO Clk < 6 3 AMIS70020 CUT_OFF Uc_Clk 4 5 > Q_Out VSS The power supplies of the chip need to be properly decoupled. This means that at least one external capacitor CDD must be connected in between VSS and VCC. Typical External Components Component Capacitor Capacitor 1 Li Battery 1, 2 Function Filter Backup power supply Backup power supply Typical Value Tol 100 +- 20% 10 +- 10% CR1220 (35mAh) Unit nF mF 1) Either a buffer capacitor of a Li-battery is selected as a backup power supply. 2) In case a Li-battery is used as a backup power supply a diode is must be placed between the AMIS-70020 and the battery to disable the charging feature. 7.0 Electrical and Environmental Ratings Operating Ranges Operation outside the operating ranges for extended periods may affect device reliability. Total cumulative dwell time above the maximum operating rating for power supply or temperature must be less than 100 hours. This section defines the limits for functional operation and parametric characteristics of the device as described elsewhere in this document. Note that functionality of the IC outside the operating ranges is not guaranteed. Symbol VCC VDD Tamb Tj Cla VIH VIL VOH VOL Description Power supply voltage Power supply voltage Ambient temperature under bias Junction temperature Load capacitance on outputs Digital input levels Min 4.5 2 -10 Digital output levels 2.5 AMI Semiconductor www.amis.com Max 5.5 5.5 85 135 70 70% VDD 3 Unit V V °C °C pF V 30%VDD V V 0.4 V Input operating range of digital IO’s 0-VDD Output operating range of digital IO’s 0-VDD AMIS-70020 Power Failure Elapsed Time Counter Data Sheet Absolute Maximum Ratings Stresses above those listed in this clause may cause immediate and permanent device failure. It is not implied that more than one of these conditions can be applied simultaneously. Symbol VCC VDDmr Tamb,mr Tj,mr VIH VIL Description Power supply voltage Power supply voltage Ambient temperature under bias Junction temperature Digital input levels Min -0.3 -0.3 -10 Max 7 7 85 150 VDD + 0.3 VDD – 0.3 Unit V V °C °C V V Electrical Overstress Immunity Latch-up immunity: (2) Static latch-up protection level is 100mA at 25°C when tested according to EIA/JESD78. Electrostatic discharges on component level: (1) The device withstands 2000V Human Body Model ESD pulses when tested according to MIL STD 883 method 3015.5 (pin combination 2). 8.0 Detailed Electrical and Functional Description Digital Interface An internal pull down resistor is connected to the pin Q_OUT, in order to avoid the parasitic shift of the counting register. The digital interface with a microcontroller can be made by means of only two digital connections. The first is the clock signal to be applied to the AMIS-70020 UC_CLK pin and the second is the data line to be read by the microcontroller from the Q_OUT pin. After a POR or after a power failure (CUT_OFF) the 15 bit shift register is loaded with the counter value and connected to the Q_OUT pin. The most significant bit, MSB is already present and can be read at the Q_OUT pin. Applying clocks at a maximum rate of 10MHz on UC_CLK will shift out the remaining counter bits. After the fifteenth clock, the internal oscillator frequency will be connected to the Q_OUT pin as a running clock signal. By measuring the period of this signal, the time a cut-off was present can be calculated by the microcontroller. AMI Semiconductor www.amis.com If VCC is powered up, a third optional pin – CLK - gives the counter clock signal of about 1Hz. This clock is the internal oscillator, divided by 1024 and can also be used to calibrate the application. Connections made with the microcontroller are separated by level shifters. When in power failure mode, the inputs of the AMIS-70020 are fixed to zero state. This will prevent unwanted current leaking. 4 AMIS-70020 Power Failure Elapsed Time Counter Timing Diagram Flowchart The flowchart depicts the operation of the AMIS-70020 in case VCC gets smaller than VDD-VTH. After this flow has been finished the buffer capacitor is recharged and the timer IC is ready for a new cycle. AMI Semiconductor www.amis.com 5 Data Sheet AMIS-70020 Power Failure Elapsed Time Counter Data Sheet Description of the Main Building Blocks Oscillator frequency. This can be done since the oscillator output frequency can be measured by the microcontroller on the Q_out pin after the measured counter value has been shifted out the register. The AMIS-70020 integrates an oscillator that functions without any external components. The maximum accuracy of the time measurement can only be obtained if the measured time is calibrated with the actual oscillator Symbol Fosc Description Absolute frequency at ambient Min 0.5 Typ 0.9 Max 1.9 Unit kHz Typ 1.4 Max 1.75 Unit V Comparator When VCC < VDD – VTH, the comparator output (CUT_OFF) is commuted. CUT_OFF signal is used by the digital control to put the circuit in cut_off mode. Symbol VTH Description VDD-VCC threshold AMI Semiconductor www.amis.com Min 0.75 6 AMIS-70020 Power Failure Elapsed Time Counter Power on Reset Symbol Vpor THreset TLreset Min Typ Max 1.65 2.25 3.08 Value not testable Value not testable Unit V Cut_off Switch It is controlled by cut_off_ctrl when the comparator and filter have detected the loss of VCC, in this case the switch is OFF. Symbol Ron Description Resistance ON of the switch Min 250 Typ Max 500 Unit Ω Description Min DC current in cut_off mode 0.1 No load at the pin Test_OUT, Q_OUT Typ Max Unit 0.5 1 µA Current Consumption Symbol IDD Revision Number Version 1.1 Changes on page AMI Semiconductor www.amis.com © Copyright 2003 AMI Semiconductor – All rights reserved. Information furnished is believed to be accurate and reliable. However, AMI Semiconductor assumes no responsibility for errors or omissions in the information and for the consequences of use of such information. AMI Semiconductor reserves the right to change the information contained herein at any time without notice. This information is provided “AS IS” without warranty of any kind, either expressed or implied, including, but not limited to, the implied warranties of merchantability, fitness for a particular purpose, or non-infringement of intellectual property. 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