HT45F6530 AVR – AC Voltage Regulator …HT45F6530 AVR – AC Voltage Regulator Application Note AN0498E 5 / 10 October 8, 2018 1. Initialisation: System settings, pin initialisation,

HT45F6530 AVR – AC Voltage Regulator Application Note

AN0498E 1 / 10 October 8, 2018


D/N：AN0498E

Introduction AC Voltage Regulators, or AVRs for short, are required in some countries where and

regions where the voltage supply is not stable. Instable electrical supplies can cause the

failure or shorten the life of electrical appliances. Installing an AVR can provide a stable

supply voltage for more sensitive appliances. The HT45F6530 is a dedicated MCU

developed by Holtek for relay-type AVRs. This application note will introduce the working

principles of AC voltage regulators and explain the various functional control processes to

offer users a deeper understanding of how to use this dedicated Holtek AVR MCU.

Functional Description

AVR AC Voltage Regulator Functional Description

By using different transformers, a wide range of voltage inputs and fixed voltage output

voltage can be achieved. This application note will use an input voltage of AC110V ~

230V/50Hz and an output voltage of AC230V ±6%/Hz relay type AVR scheme.

At the AVR core is a multi-tap self-coupled transformer and control board. Multi-tap

transformers can make the input voltage experience a multi-stage increase/decrease

conversion. The control board measures the input voltage and controls the relay switching

according to the input voltage level, so that the output voltage remains close to AC230V.

This Holtek AVR device solution can measure the relay's pull-in and release delay time,

detect the relay switching zero-point, reduce relay switch arcing thus increasing the relay

service life. The AVR has other functions such as input/output voltage display, indicators,

undervoltage/overvoltage/overtemperature/overload protection as well as power-on output

delay control.


AN0498E 2 / 10 October 8, 2018

Hardware Block Diagram

AVR- AC Voltage Regulator Hardware Block Diagram

1. After power is applied, the multi-tap self-coupled transformer is used to implement an

increase or decrease conversion to provide a multi-stage voltage for the output. The

transformer also provides a 12V AC supply for the control board power.

2. The 12V AC supply provides 12V DC and 5V DC for the relay and MCU after

rectification and step-down.

3. The AC input terminal and the AC output terminals pass through resistor circuits and

which together with an internal OCP circuit, are converted into a 2.5V center sine wave

for the internal voltage, period, zero point, relay delay and other measurements.

4. Control the relay switching according to the input voltage, so that the output remains

close to AC230V.

5. Use an NTC to measure the transformer temperature for protection.

6. Use touch switches or regular switches for switching.

7. Display input voltage, output voltage and indicator light through LED Driver.


AN0498E 3 / 10 October 8, 2018

Circuit Diagram

AVR- AC Voltage Regulator Circuit Diagram

No. AC Input Voltage

Operating Relay

Transformer Input Pin

Transformer Output Pin

AC Output Voltage

Error @AC230V

1 110~123V RL5 122 240 216~241V -6%~+5% 2 124~138V RL2, RL5 122 215 218~243V -6%~+6% 3 139~155V ─ 153 240 218~243V -5%~+6% 4 156~173V RL2 153 215 219~243V -5%~+6% 5 174~195V RL4 192 240 216~242V -6%~+5% 6 196~217V RL2, RL4 192 215 218~241V -6%~+5% 7 218~242V RL2, RL3 Bypass Bypass 218~242V -6%~+5% 8 243~270V RL3 240 215 217~241V -6%~+5%

AVR- AC Voltage Regulator Input/Output Conversion

MCU Operating Environment VDD=5V

Oscillators：8MHz

Software Used Peripheral Description ROM：4K×16 (uses 1147×16 Percentage：56%)

RAM：128×8 ( uses 50×8 Percentage：39%)

ADC：uses high 8-bits, used for input voltage, output voltage and temperature

measurement


AN0498E 4 / 10 October 8, 2018

DAC0：Output 2.5V reference voltage for OPA conversion and zero detection

DAC1：Output reference for relay delay detection

OPA0：Used for input voltage conversion

OPA1：Used for output voltage conversion

CMP0：Used for zero detection

CMP1：Used for relay delay detection

Timer：Uses CTM0 as a Timer Counter measurement, depending upon the function

set as 0.1ms and 0.25ms interrupt

The following shows how the Timer is used:

0.1ms interrupt is used to measure the input voltage cycle time and relay delay time

0.25ms interrupt is used to sample the ADC input voltage and to obtain the input

voltage peak-to-peak value

Software Flow Description

Start

Initialisation

4 AC_IN periods

AC_IN period measurement

Relay delay time measurement

AC_IN voltage measurement

AC_IN period


AC_OUT voltage measurement

Relay condition setup

Temperature measurement

Display and key status

Y

N

Y

N

AVR Main Program Flow Diagram


AN0498E 5 / 10 October 8, 2018

1. Initialisation: System settings, pin initialisation, OCP correction, RAM clear.

2. Use OCVP to count 4 AC_IN zero crossing interrupts and wait for the system to

stabilise.

3. At the next AC_IN zero point interrupt, set the CTM0 0.1ms interrupt once, count

AC_IN one cycle time.

4. Switch RL1 at the next zero point and set CTM0 0.1ms to interrupt once. Determine

the time when _CMP1O changes from 0 to 1, which is the RELAY pull-in delay time.

Release the RELAY at the next zero point when judge _CMP1O changes from 0 to 1

and then change from 1 to 0, which is the delay time for the relay to release.

5. Use the ADC to measure AC_IN once every 0.25ms, measure the peak-to-peak

value in one cycle, and evaluate the voltage level.

6. Wait for 10 AC_IN zero crossings to be interrupted.

7. Use the ADC to measure AC_IN once every 0.25ms, measure the peak-to-peak

value in one cycle, and evaluate the voltage level.

8. Use AC to measure AC_OUT once every 0.25ms, measure the peak-to-peak value

in one cycle, and evaluate the voltage level.

9. Set the relay status and wait for the timer zero output. There are 10 relay status

conditions (including overvoltage and undervoltage) with 9 levels. In order to avoid

continuous relay switching at the critical point, each gear will have ±1 ADC and 3 AC

cycle buffering.

10. Temperature measurement

11. Screen display

12. Return to the 6th loop


AN0498E 6 / 10 October 8, 2018

OCP_ISR

General Mode

AC_IN period reset


AC_OUT period measurement

AC_OUT voltage measurement

Relay delay time measurement

AC_IN zero crossing count +1

Return

• CTM0 setup as 0.1ms and restart• CTM0 timer clear

• Renew AC_IN voltage• CTM0 setup as 0.1ms and restart• Set next mode = General Mode

AC_IN period measurement

AC_IN voltage reset

AC_OUT period reset

AC_OUT voltage reset

• AC_IN voltage reset• CTM0 setup as 0.25ms and restart• Set next mode = AC_IN voltage

measurement mode

• Renew AC_IN period• CTM0 setup as 0.1ms and restart• Set next mode = General Mode

• AC_IN period reset• CTM0 timer clear• Set next mode = AC_IN period

measurement mode

• Renew AC_OUT voltage• CTM0 setup as 0.1ms and restart• Set next mode = General Mode

• AC_OUT voltage reset• CTM0 setup as 0.25ms and restart• Set next mode = AC_OUT voltage

measurement mode

• Renew AC_OUT period• CTM0 setup as 0.1ms and restart• Set next mode = General Mode

• AC_OUT period reset• CTM0 timer clear• Set next mode = AC_IN period

measurement mode

• RL1 ONDAC1=2.524V(814H)

• CTM0=0.1ms and restart• Step counter +1

Step counter

• CTM0=0.1ms• Set next mode = General

Mode

0 or 4

8

Rising edge triggerY

N

Y

Y

Y

Y

Y

Y

Y

Y

Y

Y

N

N

N

N

N

N

N

N

N

N

AVR Software OCP Interrupt Program Flow

OCP_ISR is the AC_IN zero point interrupt program. The program is only executed when

the rising edge is triggered. It is divided into three modes:

Relay delay measurement: the time from the MCU drive signal to the actual relay

pull-in/release.

Voltage/cycle measurement: divided into 4 measurement types, which will be reset

before each measurement.

Measure the maximum/minimum value of AC_IN, execute every 0.25ms and

measure the peak-to-peak value of one cycle.


AN0498E 7 / 10 October 8, 2018

Measure the period of AC_IN, count every 0.1ms and count the time of one cycle.

Measure the maximum/minimum value of AC_OUT, execute every 0.25ms and

measure the peak-to-peak value of one cycle.

Measure the period of AC_OUT, count every 0.1ms and count the time of one

cycle.

General mode: Clear CTM0 count value and reset CTM0 to ensure there is no

cumulative error.

CTM0_ISR


General Mode

CTM0 timer value +1

Return

RL1 OFF and CTM0 timer value clearDAC1 set as 2.578V

Relay delay measurement

CTM0 timer value is RL1 ON delay timeStep counter +1

ADC measure AC_IN voltageStore smallest and largest values

ADC measure AC_OUT voltageStore smallest and largest values

YAC_OUT voltage

measurement

Step counter +1Corresponding RLY ON

Corresponding RLY OFF

RLY ON Delay

RLY OFF Delay

Step counter

CTM0 timer value is RL1 OFF delay timeStep counter +1

CMP1=1

CTM0 greaterthan 7/8 period

CMP1=1 & RL1 OFF

CMP1=0

N

Y

Y

Y Y

Y

Y

Y

Y

Y

N

N

NN

N

N

N

N

N

1 or 5

2 or 6

3 or7

AVR Software CTM0 Interrupt Subroutine Flow Chart

1. CTM0 is the only timer used by the system. It is set to execute the 0.25ms and 0.1ms

interrupt depending on the function.

0.1ms interval is used to measure AC_IN/OUT AC power cycle and relay ON/OFF

delay timing

0.25ms interval is used for AC_IN/OUT voltage measurement

(tADCK=1μs, the ADC is converted six times per measurement, discard the first and

last ones, the remaining 4 times average, which takes 0.16ms)

2. Voltage measurement: Each time the interrupt is used to measure the voltage of the

corresponding port and to save the maximum and minimum values.

3. Relay delay measurement: According to different step counter values, determine the

state of CMP1 to measure the delay time of RLY ON/OFF.

4. General mode: Counting starts from each zero point. When the counting time is equal

to the delay time of the AC power cycle minus RLY ON, the RLY state is determined

and then set to ON. When the count time is equal to the delay time of the AC power

cycle minus RLY OFF, the RLY state is determined and then set to OFF.


AN0498E 8 / 10 October 8, 2018

Relay Delay Detection Timing Diagram

OPA1O

RL1

CMP1ORLY ON

Delay TimeRLY OFF

Delay Time

7/8 AC Period 7/8 AC Period

RLY ON Delay Time

RLY OFF Delay Time

OPA0O

OCP0 IRQ &Rising Edge




11 22 33 55 11 22 33 5544 44

AVR Relay Delay Detection Timing Diagram

1. After entering the relay delay measurement mode, at the first OCP rising edge

interrupt, RELAY ON, reset CTM0 and set to the 0.1ms interrupt. The CMP1 trigger

level is set to 2.524V.

2. When RLY is actually turned ON, the OPA1 potential rises above 2.524V and CMP1O

outputs a “1”. The RLY ON time is saved in the CTM0 interrupt. CTM0 continues to

count.

3. When the CTM0 count is greater than 7/8 of the AC cycle, RLY OFF, reset CTM0 and

return to zero. The CMP1 trigger level is set to 2.588V waiting for CMP1O=1.

4. Continue counting and wait for CMP1O=0.

5. After RLY is actually turned OFF, the OPA1 potential drops below 2.578V and

CMP1O outputs a “0”, and the RLY OFF time is saved in the CTM0 interrupt, after

which the measurement ends. Next time when the OCP rising edge interrupt occurs,

execute from step 1 again.

* The first time power is applied, due to different loads the waveform response will be

slow therefore the first measurement data cannot be used.

Voltage Measurement Timing Diagram ADC

128

255

0 TIME

MAX

MIN

20ms

0.25ms

AVR Voltage Measurement Timing Diagram


AN0498E 9 / 10 October 8, 2018

1. When measuring the AC IN/OUT voltage, CTM0 is set to be interrupted every 0.25ms.

2. Perform ADC measurements and update MAX and MIN for each interrupt. Taking 50

Hz as an example, 80 voltage measurements are performed within a 20 ms cycle.

3. After the measurement is completed, subtract MIN from MAX to get the AC IN/OUT

peak-to-peak voltage value.

(tADCK=1μs, the ADC is converted six times per measurement, discard the first and last

ones, the remaining 4 times average, which takes 0.16ms)

Relay Control Timing Diagram

RLY ON Delay Time

RLY OFF Delay Time

Zero cross & CTM0 Counter=0

Zero cross & CTM0 Counter=0

AC POWER Period

CTM0 Counter=Period ct–OFF Delay ct CTM0 Counter=Period ct–OFF Delay ct

RL1~N OFF ->ON

RL1~N ON ->OFF

OPA0

AVR Relay Control Timing Diagram

1. At each AC zero crossing the rising edge on CTM0 will return to zero.

2. When the CTM0 count is equal to the AC cycle minus the value of RLY ON, determine

whether relay 1~N should be set to 1.

3. When the CTM0 count is equal to the AC cycle minus the value of RLY OFF,

determine whether relay 1~N should be set to 0.

Software Example

HT45F6530_Demo_V1_20180627.zip

Conclusion

This application note has described how to use the HT45F6530 to develop an AVR. It has

explained the AVR input and output voltage measurements and the operating principles

behind the relay delay time measurement and the software control flow steps. With the

device’s fully integrated OPA, CMP and DAC functions, together with the provided

sample programs, users are able to save on external components, reduce the PCB board

area as well as decrease the required development time.


AN0498E 10 / 10 October 8, 2018

Versions and Modification Information Date Author Issue Release and Modification

2018.06.25 陳振隆 (Chenlung) First Version

References

HT45F6530 Datasheet.

For more information refer to the Holtek’s official website www.holtek.com.

Disclaimer All information, trademarks, logos, graphics, videos, audio clips, links and other items

appearing on this website ('Information') are for reference only and is subject to change at

any time without prior notice and at the discretion of Holtek Semiconductor Inc.

(hereinafter 'Holtek', 'the company', 'us', 'we' or 'our'). Whilst Holtek endeavors to ensure

the accuracy of the Information on this website, no express or implied warranty is given

by Holtek to the accuracy of the Information. Holtek shall bear no responsibility for any

incorrectness or leakage.

Holtek shall not be liable for any damages (including but not limited to computer virus,

system problems or data loss) whatsoever arising in using or in connection with the use of

this website by any party. There may be links in this area, which allow you to visit the

websites of other companies. These websites are not controlled by Holtek. Holtek will

bear no responsibility and no guarantee to whatsoever Information displayed at such sites.

Hyperlinks to other websites are at your own risk.

Limitation of Liability

In any case, the Company has no need to take responsibility for any loss or damage

caused when anyone visits the website directly or indirectly and uses the contents,

information or service on the website.

Governing Law This disclaimer is subjected to the laws of the Republic of China and under the jurisdiction

of the Court of the Republic of China.

Update of Disclaimer Holtek reserves the right to update the Disclaimer at any time with or without prior notice,

all changes are effective immediately upon posting to the website.

http://www.holtek.com/

Documents

HT45F6530 AVR – AC Voltage Regulator …HT45F6530 AVR – AC Voltage Regulator Application Note AN0498E 5 / 10 October 8, 2018 1. Initialisation: System settings, pin initialisation,