Samsung S3F84B8 Guide

S3F84B8
All-in-One IH Cooker
Revision 0.00
May 2010
A
Ap pp pl li ic ca at ti io on n N No ot te e
2010 Samsung Electronics Co., Ltd. All rights reserved.

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S3F84B8 All-in-One IH Cooker
Application Note, Revision 0.00
Copyright 2010 Samsung Electronics Co., Ltd.
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in
any form or by any means, electric or mechanical, by photocopying, recording, or otherwise, without the prior
written consent of Samsung Electronics.
Samsung Electronics Co., Ltd.
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Yongin-City, Gyeonggi-Do, Korea 446-711
TEL: (82)-(31)-209-3865
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Home Page: http://www.samsungsemi.com

Revision History
Revision No. Effective Date Description Refer to Author(s)
0.00 Mar, 2010 - Initial Draft Wei Ningning
Zhang Fan

Table of Contents
1 OVERVIEW OF IH COOKER (IHC).............................................................1-1
1.1 Induction Cooking Principle ..................................................................................................................... 1-1
1.1.1 How Induction Cooking Works ......................................................................................................... 1-1
1.2 Key Features of S3F84B8........................................................................................................................ 1-2
1.3 System Principle ...................................................................................................................................... 1-3
1.3.1 Heating ............................................................................................................................................. 1-3
1.3.2 Protection.......................................................................................................................................... 1-3
2 HARDWARE IMPLEMENTATION...............................................................2-4
2.1 System Diagram and pin Assignment...................................................................................................... 2-4
2.2 Power Supply........................................................................................................................................... 2-6
2.3 Synchronization Circuit............................................................................................................................ 2-7
2.4 Power control........................................................................................................................................... 2-9
2.4.1 Voltage Measurement ...................................................................................................................... 2-9
2.4.2 Current Measurement..................................................................................................................... 2-10
2.5 System Protection.................................................................................................................................. 2-11
2.5.1 Surge Protection............................................................................................................................. 2-11
2.5.2 IGBT over Voltage Protection......................................................................................................... 2-11
2.5.3 Over/under Voltage Protection....................................................................................................... 2-11
2.5.4 Temperature Protection.................................................................................................................. 2-12
2.6 Other Functions...................................................................................................................................... 2-13
2.6.1 Pan Detection................................................................................................................................. 2-13
2.6.2 Buzzer and Fan Control.................................................................................................................. 2-13
2.6.3 Key and Display Circuit .................................................................................................................. 2-14
3 SOFTWARE IMPLEMENTATION ...............................................................3-1
3.1 State Transition Diagram......................................................................................................................... 3-1
3.2 Software Diagram .................................................................................................................................... 3-2
3.3 Internal Resource Arrangement and Configuration................................................................................. 3-4
4 APPENDIX...................................................................................................4-1
4.1 Error Code................................................................................................................................................ 4-1
4.2 Schmatic .................................................................................................................................................. 4-1
4.3 Source Code............................................................................................................................................ 4-1

List of Figures
Figure Title Page
Number Number
Figure 1-1 How IH Cooker Works...................................................................................................................... 1-1
Figure 1-2 Pin Assignment in S3F84B8............................................................................................................. 1-2
Figure 2-1 Block Diagram of IH Cooker System................................................................................................ 2-4
Figure 2-2 Power Supply Circuit ........................................................................................................................ 2-6
Figure 2-3 Power Supply Circuit ........................................................................................................................ 2-7
Figure 2-4 Waveform of the Synchronization Circuit ......................................................................................... 2-8
Figure 2-5 Voltage Measurement and Surge Protection Circuit ........................................................................ 2-9
Figure 2-6 Current Measurement Circuit.......................................................................................................... 2-10
Figure 2-7 Over-Temperature Protection......................................................................................................... 2-12
Figure 2-8 Buzzer and Fan Control.................................................................................................................. 2-13
Figure 2-9 Key and Display Circuit................................................................................................................... 2-14
Figure 3-1 State Transition Diagram.................................................................................................................. 3-1
Figure 3-2 Software Diagram............................................................................................................................. 3-2
Figure 3-3 Interrupt Service Routine Diagram ................................................................................................... 3-3
Figure 3-4 Fan and BUZ Workflow..................................................................................................................... 3-3

List of Tables
Table Title Page
Number Number
Table 2-1 S3F84B8 pin assignment in IH cooker system.................................................................................. 2-5
Table 3-1 Internal Resource Arrangement and Configuration........................................................................... 3-4
Table 4-1 Error Information................................................................................................................................ 4-1

S3F84B8_ALL-IN-ONE IH COOKER_AN_REV 0.00 1 OVERVIEW OF IH COOKER (IHC)
1-1
1 OVERVIEW OF IH COOKER (IHC)
In traditional ranges or ovens, cookware is used to transfer heat from the stove elements. However, in the IH
cooker (IHC), the cookware participates in the heat generation. This form of heat generation is known as Induction
Heating, and it improves the overall thermal efficiency of heating.
This document describes an IH cooker (IHC) system implemented with Samsung’s newly developed 8-bit MCU
S3F84B8, which is designed for an all-in-one IHC application with amplifier and comparators.
1.1 INDUCTION COOKING PRINCIPLE
According to Faraday’s Law, changing the magnetic field associated with an alternating current (AC) induces
current in a second conductor placed in that field. IH cookers work largely the same way.
1.1.1 HOW INDUCTION COOKING WORKS
This section describes how induction cooking works.
Steps:
1) The electronic components in the element power a coil, which in turn produces a high-frequency
electromagnetic field.
2) The electromagnetic field enters the ferrous metal (magnetic material) of the cookware and sets up a
circulating electric current (Eddy current), which generates heat.
3) The heat generated in the cookware is transferred internally.
4) The electromagnetic field does not affect the outer body of cookware. As soon as the cookware is removed
from the element or the element turned off, the heat generation stops.
Figure 1-1 How IH Cooker Works

S3F84B8_ALL-IN-ONE IH COOKER_AN_REV 0.00 1 OVERVIEW OF IH COOKER (IHC)
1-2
1.2 KEY FEATURES OF S3F84B8
With no more discrete ICs like LM339 (comparator IC) in previous IHC solutions, S3F84B8 successfully integrates
four comparators, one OPA, and one IH-PWM to control power directly. After configuration, all the four
comparators can cooperate with the IH-PWM automatically, which makes the time-sensitive control possible.
Figure2 shows the pin assignment in S3F84B8.
S3F84B8
20-DIP/
20-SOP
20
19
18
17
16
15
14
13
12
11
1
2
3
4
5
6
7
8
9
10
V
DD
P2.7/ADC7/(SCL)
P2.6/ADC6/(SDA)
P2.5/ADC5/CMP3_N
P2.4/ADC4/CMP2_N
P2.3/ADC3(OPA_O)
P2.2/ADC2/OPA_N
P2.1/ADC1/OPA_P
P2.0/ADC0/TDOUT
P1.2/CMP1_N
V
SS
INT0/X IN /P0.0
INT1/X
OUT /P0.1
V
PP /nRESET/P0.2
BUZ/INT2/P0.3
PWM/INT3/P0.4
INT4/P0.5
TAOUT/INT5/P0.6
TACK/CMP0_P/P1.0
TACAP/CMP0_N/P1.1
Figure 1-2 Pin Assignment in S3F84B8
The key features of S3F84B8 include:
8K Full Flash ROM and 272B SRAM
Four Comparators
One OPA
10-bit IH-PWM x 1 (can co-operate with the four Comparators)
10-bit ADC x 8
8-bit Basic Timer (can be used as Watch Dog Timer)
8-bit TimerA
16-bit Timer0 (can be used as two 8-bit Timers C/D)
External Interrupts X 6
Supports configurable LVR (1.9/2.3/3.6/3.9V)
Supports configurable internal RC (0.5M/8MHz RC @5V with maximum 3% accuracy)
Supports 18 IOs (maximum) when using internal LVR and internal RC
Comparator0 has two inputs. Its output can trigger the PWM to start a new cycle immediately or after some
programmable delay. This helps in the synchronization control. The delay can adjust the IGBT to turn on at
minimum collector voltage, thereby reducing the heat and protecting the transistor.

S3F84B8_ALL-IN-ONE IH COOKER_AN_REV 0.00 1 OVERVIEW OF IH COOKER (IHC)
1-3
Comparator1/2/3 has only one input with an internal programmable reference level. It can lock the output of PWM
to a safe level. Besides the delay trigger function, PWM can realize anti-mis-trigger function as well. It prevents
the PWM from being triggered by unexpected noise. For more information about the cooperating mechanism of
the IH-PWM and four comparators, refer to the user’s manual.
1.3 SYSTEM PRINCIPLE
To make the system work reliably, the control of IH cooker can be divided into two major parts: heating and
protection.
1.3.1 HEATING
In earlier solutions, the output of LM339 controls the IGBT. On being filtered, the PWM output transforms into an
analog signal that sets the flip level of LM339. Therefore, only the duty determines the output power.
However, in a system with S3F84B8, the PWM directly controls the switch of IGBT and the width of valid output
level determines the output power. Therefore, the power is dependent on the system clock.
1.3.2 PROTECTION
Two kinds of protection are available for the control of IH cooker: first is time sensitive protection, and the other is
acceptable protection that can be executed even after certain degree of delay.
Surge protection and IGBT over-voltage protection belong to the former class (time sensitive protection).
Therefore, these two signals use the integrated comparators. In this solution, PWM will be hard-locked when
surge protection is triggered. It stops the PWM with a safe output level until the software enables it again. Once
the voltage sensed at IGBT is beyond limitation, PWM will be soft-locked. This will make the PWM stop the current
cycle and reload PWMDATA with a preset safe value (PWMPDATA) to reduce the turn-on time of IGBT from that
instance.
Over-temperature, over-current, and over/under voltage protections belong to the latter class. They are realized by
AD conversion and software comparison.

S3F84B8_ALL-IN-ONE IH COOKER_AN_REV 0.00 2 HARDWARE IMPLEMENTATION
2-4
2 HARDWARE IMPLEMENTATION
2.1 SYSTEM DIAGRAM AND PIN ASSIGNMENT
Figure 2-1 shows the block diagram of IH cooker system.
Figure 2-1 Block Diagram of IH Cooker System

S3F84B8_ALL-IN-ONE IH COOKER_AN_REV 0.00 2 HARDWARE IMPLEMENTATION
2-5
In Figure 2-1, SMPS stands for Switch Mode Power Supply. It provides +18V DC and +5V DC to the system.
Three out of four comparators are used in this solution: one for synchronization circuit and other two for surge
protection and IGBT over-voltage protection.
Table 2-1 shows the pin assignment while using S3F84B8 in IH cooker system.
Table 2-1 S3F84B8 pin assignment in IH cooker system
Pin No. Pin Names Pin Type Pin Assignment
1 VSS I Ground
20 VDD I Power input
4 P0.2 - Reserved
2 P0.0 O DIO
3 P0.1 O CLK
7 P0.5 O
Display Board
Connector
STB
8 P0.6 O Reserved
13 P2.1 O Reserved
5 P0.3/BUZ O Buzzer and Fan control
6 P0.4/PWM O IGBT control
9 P1.0/CMP0_P I
10 P1.1/CMP0_N I
Synchronization control
11 P1.2/CMP1_N I IGBT over-voltage protection
16 P2.4/CMP2_N I Surge protection
17 P2.5/ADC5 I System voltage measurement input
12 P2.0/ADC0 I IGBT temperature sensor input
19 P2.7/ADC7 I Pan temperature sensor input
18 P2.6/ADC6 I Amplified current signal input
14 P2.2/OPA_N I System current measurement input
15 P2.3/OPA_O O Operational Amplifier output

S3F84B8_ALL-IN-ONE IH COOKER_AN_REV 0.00 2 HARDWARE IMPLEMENTATION
2-6
2.2 POWER SUPPLY
Figure 2-2 shows the circuit diagram for power supply.
1 5
6
4 8
T1
EE-19
D5
UF4007
D4
8
D3
7
D2
6
D1
5
S1 1
S2 2
FB 3
VDD 4
U1
VIPER12A
220 VAC
D1
1N4007
+ C8
10uF/50V
VIN 1
GND 2
VOUT 3
IC1
78L05
D7 UF4007
Z1
18V
+ C6
100uF/25V
+
C2
4.7uF/450V
C1
102/1KV
R1
100K/0.5W
+
C21
100uF/25V
+ C13
100uF/16V
AC_L
+5V
D2
UF4007
AC_N
D6
1N4007
C3
104
D7
1N4007
D4 UF4007
L1
330uH
+18V
Figure 2-2 Power Supply Circuit
The power circuit contains a transformer, an SMPS primary switcher, and a +5V DC regulator. After passing
through a half-wave rectifier and an LC filter, the 220V AC power enters the primary side of transformer.
Thereafter, VIPER12 and 78L05 produce stable +18V DC power for the transistors and +5V DC power for the
MCU and other devices.

S3F84B8_ALL-IN-ONE IH COOKER_AN_REV 0.00 2 HARDWARE IMPLEMENTATION
2-7
2.3 SYNCHRONIZATION CIRCUIT
R9
2KJ
R23 2K
C23 102
+18V
R12
2K7
R6
220K/0.5W
FUSE1
10A/250V
1
4
3
2
-+
BRIDGE
D15XB80H18
R28 51R
+ C28
25V/100uF
D8
4148
R36
10R
R37
10K
C22
0.1uF/275V
SYS_I
Q1
8050
R25
24K Syn_P
Q5
8550
Q4
8050
L2
CHOKE IGBT
FGA15N120
L3
IGBT_V_P
IGBT Driver
C20
0.24uF/1200V Q2 8050
R21
2K
IGBT over voltage protection
R22
2K
C17
101
COOKER
C19
4uF/400V
IGBT_CTRL
R7
220K/0.5W
R8
220K/0.5W
R50
CONSTANTAN
AC_L
AC_N
R24
1K
R3
470K/0.5W
R10
470K/0.5W
R2
220K/0.5W
R11
5K6
Syn_N
PWM
Figure 2-3 Power Supply Circuit

S3F84B8_ALL-IN-ONE IH COOKER_AN_REV 0.00 2 HARDWARE IMPLEMENTATION
2-8
IH heating is the result of Eddy current caused by LC resonance. For a general cookware, the oscillation
frequency may vary from 20KHz to 30KHz. Since heating consumes energy, the IGBT should be periodically
turned on to allow the 220V power to compensate for the energy loss. Obviously, the longer it is turned on, the
more energy can be accumulated.
When the PWM output turns on the IGBT, electric energy is stored in the inductance and free LC oscillation is
started when the IGBT is turned off (as shown in Figure 2-3).
To make the system work stably, consider the turn on frequency and turn on time of the IGBT. First, the turn on
frequency cannot destroy the LC oscillation, even though the IGBT on time will affect it a little bit. This means the
frequency of PWM output should be synchronized with the LC oscillation. It is realized by comparator0.
Second, considering the withstand voltage of IGBT, it is better to turn it on when the collector voltage is near ‘0’. It
can be realized by adjusting the divider resistors and enabling the delay trigger function of the IH PWM module. At
the same time, when proper delay time is set, thermal radiations will be largely reduced.
Figure6 shows the waveform of synchronization circuit. Light and dark blue waveforms show the inputs of
comparator0. The green waveform is measured at P0.4 (PWM). Additionally, the crossing point of the light and
dark blue waveforms trigger the rising of PWM output (High level at the base) which turns on the IGBT. The
duration of PWM’s outputting high is the result of software power control. When PWM output (green waveform)
returns to low level, the light and dark waveform presents free oscillation of the circuit, though the existence of the
IGBT diode makes the oscillation waveform not an ideal one.
Figure 2-4 Waveform of the Synchronization Circuit

S3F84B8_ALL-IN-ONE IH COOKER_AN_REV 0.00 2 HARDWARE IMPLEMENTATION
2-9
2.4 POWER CONTROL
Power is the product of voltage and current (P = V x I). Figure 2-5 and Figure 2-6 show the measurement circuit of
system voltage and current, separately.
2.4.1 VOLTAGE MEASUREMENT
Figure 2-5 shows the circuit diagram for voltage measurement and surge protection.
R20
29K
+
C16
10uF/50V
SYS_V
R27
6K8
C18
221
Surge_P
220 VAC
AC_L D9 1N4007
AC_N D10
1N4007
surge protection
R17
470K/0.5W
R19
820K/0.5W
R18
820K/0.5W
C15
102/1KV
Figure 2-5 Voltage Measurement and Surge Protection Circuit
Resistor divider decreases the voltage level to the proper ADC range.

S3F84B8_ALL-IN-ONE IH COOKER_AN_REV 0.00 2 HARDWARE IMPLEMENTATION
2-10
2.4.2 CURRENT MEASUREMENT
R4 1K
OPA_O
R13 36K RW1
10K
OPA_N
C10
104J
SYS_I
+
C12
1uF/16V
CURRENT
R14 100K
R15
22K
S3F84B8
R
f
R 1
OPA
_
N
OP
A
_
P
OP
A
_
O
Gain
= - R
f
/
R1
Figure 2-6 Current Measurement Circuit
In the IH cooker system, the current can go as high as 10A. To avoid excessive energy loss, a constantan is used
to change the current signal to voltage signal, which is then amplified by the integrated OPA. Finally, the amplified
signal enters the ADC module. Note that the signal (OPA_N) reaching OPA is negative as compared to MCU
GND. Therefore, OPA has to work as an inverting amplifier with negative gain.
Either the OPA offset or the resistance deviation can lead to inconsistency of output power among different chips.
To get precise power control, two calibrating methods are used. In hardware, a variable resistor (RW1) is chosen,
whereas in software algorithm, the overall offset is measured and calculated before the system starts working. It
likes the quiescent bias that should be removed during normal operation. This way the output power can be
controlled within 10W deviation.

S3F84B8_ALL-IN-ONE IH COOKER_AN_REV 0.00 2 HARDWARE IMPLEMENTATION
2-11
2.5 SYSTEM PROTECTION
2.5.1 SURGE PROTECTION
Figure 2-5 shows the circuit diagram for surge protection. In this figure, Surge_P specifies the negative input of
Comparator 1. Also, reference voltage is internally set as 0.55VDD. When surge takes place, that is, V Surge_P >
0.55VDD, the falling edge of comparator 1 can hard-lock the PWM output immediately to prevent the IGBT from
being burnt out by over current. The whole system then stops work and restarts after some delay.
2.5.2 IGBT OVER VOLTAGE PROTECTION
IGBT over voltage is most likely to occur the moment when the pan is removed from the panel.
Figure 2-5 shows the voltage measurement circuit. In this figure, IGBT_V_P specifies the negative input of
Comparator 2. Also, reference voltage internally is set as 0.70VDD. When V Surge_P > 0.70VDD, the co-
operation of comparator 2 and IH PWM will soft-lock the PWM output immediately to prevent the IGBT from being
burnt out by over stress of the collector voltage. As a result, it makes the PWM stop the current cycle and reload
PWMDATA with a preset safe value (PWMPDATA) to reduce the turn-on time of IGBT.
2.5.3 OVER/UNDER VOLTAGE PROTECTION
Over/under voltage protection uses the voltage measurement signal. The protection takes place when the AD
conversion result is either too large or too small. The whole system then stops working until the power returns to
normal.

S3F84B8_ALL-IN-ONE IH COOKER_AN_REV 0.00 2 HARDWARE IMPLEMENTATION
2-12
2.5.4 TEMPERATURE PROTECTION
Figure 2-7 shows the circuit diagram for temperature protection.
C4
104
R5
10K
RT1
100K3950
IGBT_T
+5V
PAN_T
a) Pan temperature protectionb) IGBT temperature protection
C25
104 R29 3K
1
2
CN5
T_PAN
+5V
Figure 2-7 Over-Temperature Protection
RT1 is a thermistor located just beneath the IGBT. CN5 is the connector for the thermistor near the pan.
For IGBT temperature protection, there are two kinds of scenarios:
When the temperature rises above 85℃, the set level of output power will automatically downgrade.
When the temperature continues to rise above 90℃, the system will shut down and will remain in that state
until it is restarted manually.
For pan temperature, the system will be shut down when the temperature is over 230℃.
The threshold of protection level can differ, according to the different locations of the thermistor.
Meantime, when the sensed voltage level is close to 5V or 0V, the sensor can be viewed as broken. The whole
system then stops working until it is restarted manually.

S3F84B8_ALL-IN-ONE IH COOKER_AN_REV 0.00 2 HARDWARE IMPLEMENTATION
2-13
2.6 OTHER FUNCTIONS
2.6.1 PAN DETECTION
Pan-on detection is executed every 2sec when the system is idle. It is useful when you press the Start key first
and then put the pan on. In principle, even though the IGBT is turned on, there will not be any oscillation before
the pan is put on the panel. In S3F84B8, comparator 0’s output can be set as the clock source of Timer C. After
starting 1-cycle PWM output and waiting for about 3 oscillation cycles, if TCCNT>1, Pan status = on; else Pan
status = off. Pan-remove detection is executed every 1.5s when the system is working. It is useful when you
directly remove the pan from the panel without pressing the Stop key.
Pan-remove detection is done by current measurement, that is, when the sensed current is small, the system
considers the pan as removed and turns idle.
2.6.2 BUZZER AND FAN CONTROL
Figure 2-8 shows the circuit diagram for buzzer and fan control.
+
C24 104M/50V BUZZER1
Q3
8050
1
2
CN3
FAN
+18V
R26
1K
BUZ/FAN
Figure 2-8 Buzzer and Fan Control
The fan cools down the system while heating. Buzzer indicates error and key actions.
In Figure 2-8, buzzer and fan share the same I/O. Due to C24, the DC signal controls fans on and off, while
square wave with high frequency determines the buzzer’s beep.
Note that C24 cannot be too large; else it will deteriorate the power of MCU and make the integrated analog
modules work unstably.

S3F84B8_ALL-IN-ONE IH COOKER_AN_REV 0.00 2 HARDWARE IMPLEMENTATION
2-14
2.6.3 KEY AND DISPLAY CIRCUIT
Figure 2-9 shows the circuit diagram for key and display.
SEG8/KS8
SEG4/KS4 SEG5/KS5 GRID4
GRID3
SEG1/KS1 SEG2/KS2 SEG3/KS3
GRID7
GRID6
GRID5
5V
GND
GRID4
SEG8/KS8
K4 KEY K2 KEY
K3
KEY
K1
KEY
K5
KEY
K6
KEY
K7
KEY
K8
KEY
KEY1
KEY2
2 1
R9 constant
2 1
R7 constant
2 1
R10 constant
2 1
R11 constant
2 1
R12 constant
2 1
R14 constant
GND
GRID2
GRID1
SEG3/KS3 SEG1/KS1
1 2
D1
LED
SEG4/KS4
1 2
D2
LED
SEG5/KS5
1 2
D3
LED
1 2
D4
LED
SEG6/KS6 SEG8/KS8
SEG1/KS1
SEG4/KS4
2 1
R18 constant
SEG3/KS3
2 1
R17 constant
GRID7
0
0
21 R6
constant
5V
21
R8
constant
+
C26
PF
12
C27
PF
GND
21
R29
constant
21
R32
constant
0
5V
KEY1
KEY2
SEG1/KS1
5V
NC
1
DIO
2
CLK
3
STB
4
KEY1
5
KEY2
6
VDD0
7
SEG1/KS1
8
SEG2/KS2
9
SEG3/KS3
10
SEG4/KS4
11
SEG5/KS5
12
SEG6/KS6
13
SEG7/KS7
14
GND0 28
GRID1 27
GRID2 26
GND 25
GRID3 24
GRID4 23
GND1 22
VDD1 21
SEG14/GRID5 20
SEG13/GRID6 19
SEG12/GRID7 18
SEG10 17
SEG9 16
SEG8/KS8 15
U2
TM1628
11 22 33 44 55 66
7
7
8
8
9
9
10
10
11
11
12
12
D8
4LED
SEG4/KS4
SEG3/KS3
SEG2/KS2
GRID1
SEG5/KS5
SEG6/KS6 SEG7/KS7
GRID2
SEG7/KS7
SEG6/KS6
GRID3
Figure 2-9 Key and Display Circuit
There are eight keys for power on, power grade selection, and some LEDs to display the operating status and
power grade. TM1628 controls the key and display circuit. MCU communicates with TM1628 through three I/Os:
DIO for data transfer, CLK as serial clock, and STB for chip enable.