FEATURES
* Wide operation voltage range, 2.4V to 6V
* Eight data key control
* Option of signal-key or multi-key control
* Two custom codes to separate products
* Auto power off for saving power
* LED output to indicate transmission status
* Direct infrared LED 38KHz modulation output
* Low power consumption
* Paired with SM5032 decoder
* 16 pin DIP or SO package
APPLICATIONS
* SM3015 Fan Remote Control
* Audio Remote Control
* Toy Remote Control
* Consumer Products Remote Control
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V.2.0 Mar 8,2002
PIN ASSIGNMENT (TOP VIEW)
GENERAL DESCRIPTION
The SM5021A/B is a high performance
infrared remote control encoder utilizing
CMOS technology. Mode A is a signal-key
control and mode B is a multi-key control
during data transmission, supports eight data
key inputs and a LED output to indicate the
status during transmission.
Auto power off function when key is not
pressed to save power, custom codes to
distinguish different products. SM5021
encoder is paired with SM5032 decoder for
more data control applications.
VDD
DOUT
LEDO
OSC2
OSC1
K8
K7
K6
1
16
2
15
3
14
4
13
5
12
6
11
7
10
8
9
SM5021A/B
C1
C2
K1
K2
K3
K4
K5
Vss
SM5021
S
AM
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Microelectronics Corp.
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V.2.0 Mar 8,2002
BLOCK DIAGRAM
Vss
V
DD
XTAL OSC
Key In Latcg And
Error Detect
Timing Generator
Encoder
Output Drive
C1
C2
DOUT
LEDO
K3
K4
K5
K6
K7
K8
K1
K2
OSC1
OSC2
Bit_ CK
Filed_CK
Frame_CK
Latch Key
PIN DESCRIPTION
K1 ~ K8
I
Remote Control Key Inputs
(Built-In Pull-Low Resistor)
Vss
POWER
Negative Power Supply ( Substrate )
OSC1
I
455KHz XTAL OSC Pin
OSC2
O
455KHz XTAL OSC Pin
DOUT
O
Signal Output
LEDO
O
Transmission Indicator
V
DD
POWER
Positive Power Supply
Pin Name
I / O
Function
C1,C2
I
Custom Code
SM5021
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Microelectronics Corp.
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FUNCTION DESCRIPTION
There are four frames, encoder generates during sending. Each frame contains four field:
a) Frame head / Three-bits
1 1 0 ( Metal option )
b) Custom code / Two-bits
C1 C2
c) Control word / Seven-bits
0 0 0 0 0 0 1 ~ 1 0 0 0 1 1 0
d) Synch field / Four-bits of empty
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V.2.0 Mar 8,2002
Frame Format
B. Transmission Code Table
Start Word
Custom Code B1 B2 B3 B4 B5 B6 B7
Transmit
A. Encoder Singal Output Format
Bit Format
EMPTY
Logic 0 is
Logic 1 is
SYSCK / 192
1 1 0
1 1 0
1 1 0
1 1 0
1 1 0
1 1 0
1 1 0
1 1 0
C1 C2
C1 C2
C1 C2
C1 C2
C1 C2
C1 C2
C1 C2
C1 C2
0 0 0 0 0 0 1
0 0 0 0 0 1 0
0 0 0 0 1 0 0
0 0 0 1 0 0 0
0 0 1 0 0 0 0
0 1 0 0 0 0 0
1 0 0 0 0 1 1
1 0 0 0 1 1 0
K1
K2
K3
K4
K5
K6
K7
K8
SM5021
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Microelectronics Corp.
ENCODER
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V.2.0 Mar 8,2002
C. Transmission Timing
* t1: Key pressing > 32ms
* t2: Transmission time t3 + 108ms ( Four frame )
If t1 is over t3 + 108ms, DOUT will be transmitted again.
[ ( Pressing time ) MOD ( t3 + 108ms ) + 1 ] * 108ms + t3
* t3: Oscillator stable time. OSC * 384 = 0.8ms
* t4: 3-Bits( Head ) + 2-Bits( Custom Code ) + 7-Bits( Data ) + 6-Bits( Empty ) = 18-Bits (27ms)
* OSC: 455KHz resonator
Key In
t1
OSC
LED
t2
DOUT
t3
t4
Frame 1
Frame 2
Frame 3
Frame 4
SM5021
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Microelectronics Corp.
ENCODER
Page 5
V.2.0 Mar 8,2002
D. SM5021A Transmission Waveform
Normal Condition
DOUT
F1
F2
F3
F4
F1
F2
F3
F4
F1
F2
F3
F4
OSC
LED
Key2
Key 1
DOUT
OSC
Overlap Condition
If more than one key is pressed, transmission stops.
LED
Key2
Key 1
t > 32ms
F1
F2
F4
F3
F2
F1
SM5021
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Microelectronics Corp.
ENCODER
Page 6
V.2.0 Mar 8,2002
E. SM5021B Transmission Waveform
Normal Condition
DOUT
OSC
LED
Key2
Key 1
OSC
Overlap Condition
If more than one key is pressed, multi-key data transmission.
LED
Key2
Key 1
t > t3 + 108ms
t > 32ms
DOUT
F
F
F
F
F
F
F
F
F
F
K1
K1
K2
K2
K2
K2
K2
K2
[ K1+K2 ]
F1
F2
F3
F4
F1
F2
F3
F4 F1
F2
F3
F4
SM5021
S
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H
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Microelectronics Corp.
ENCODER
-0.3 ~ 6
Vss -0.3 ~ V
DD
+0.3
Vss -0.3 ~ V
DD
+0.3
500
-10 ~ 70
-40 ~ 125
Test Conditions
ABSOLUTE MAXIMUM RATINGS
Parameter
Ratings
Unit
Page 7
DC ELECTRICAL CHARACTERISTICS
V.2.0 Mar 8,2002
Symbol
V
DD
- Vss = 5V
Supply Voltage
Input Voltage
Output Voltage
Maximum Power Consumption
Operating Temperature
Storage Temperature
V
V
V
mW
V
DD
-Vss
V
I
V
O
Pa
Topr
Tstg
Parameter
Conditions
Unit
Limit
Symbol
Min. Typ. Max.
Supply Voltage
V
V
DD
2.4
3
6
Stand-by Current
V
DD - Vss
= 3V
OSC stop
all output pins open
I
SB
A
1
Input High Level
V
V
IH
1.5
3.5
Input Low Level
V
VIL
0
1.5
DOUT Source Current
V
OH
= +2.4V
mA
I
OH
5
LEDO Source Current
V
OH
= +2.4V
I
OH
DOUT Sink Current
V
OL
= +0.4V
mA
I
OL
5
mA
7.5
SM5021
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Microelectronics Corp.
ENCODER
APPLICATION CIRCUIT
Page 8
V.2.0 Mar 8,2002
VDD
DOUT
LEDO
OSC2
OSC1
K8
K7
K6
SM5021
C1
C2
K1
K2
K3
K4
K5
Vss
JP1
JP2
C1
BT
3V
10u
D2
IR
LED
R2
4.7
Q1
NPN
Q2
NPN
D1
LED
R1
1K
455K
SM5021
S
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H
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Microelectronics Corp.
ENCODER
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