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CH450 PDF даташит

Спецификация CH450 изготовлена ​​​​«ETC» и имеет функцию, называемую «LED drive and keyboard control chip».

Детали детали

Номер произв CH450
Описание LED drive and keyboard control chip
Производители ETC
логотип ETC логотип 

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CH450 Даташит, Описание, Даташиты
www.DataSheet.co.kr
The DataSheet of CH450 (the first)
1
LED drive and keyboard control chip CH450
English DataSheet
Version:1C
http://wch.cn
1. Introduction
CH450 is numeric LEDs display drive and keyboard scan control chip. CH450 sets clock surging
circuit internal, drives six bits numeric LEDs or forty-eight LEDs automatically. And it carries out
forty-eight keys keyboard scan. CH450 exchanges data with MCU via two wires serial interface and supplies
power-up reset signal to MCU.
SCL SEG7SEG0
MCU
etc
SDA
INT#
RSTH
CH450 chip
(broken line
are optional)
8×6 matrix
48 keys
keyboard
DIG7DIG2
Six bits
numeric
LEDs or
forty
eight
LEDs
2. Features
Set display current drive layer internal, the segment current is no less than 15mA, the word current is no
less than 80mA.
Dynamically display scan control, directly drive six bits numeric LEDs or forty eight LEDs.
Set forty eight keys keyboard controller internal, basic on 8×6 matrix keyboard scan.
Set pull-down resistor internal on the key pressed station, and set eliminate dithering circuit internal.
Supplies keyboard interrupt active with low-level, supplies key-press release sign bit, to detect key is
pressed or released.
High-speed two wires serial interface, the speed of clock varies from 0 to 4MHz,compatible with two
wires I2C bus, save pins.
Set clock surge circuit internal, the outside supplies clock or surging equipments is no need, stand against
disturbing.
Set clock surging circuit internal, dont need outside to provide clock or connect surge device,
anti-jamming capability is more stronger.
Set power-on reset internal, supplies reset output active with high-level to MCU.
Supplies DIP20 and SOP20 package without lead, compatible with RoHS, the function and pins are
compatible with CH455 in some parts.
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CH450 Даташит, Описание, Даташиты
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The DataSheet of CH450 (the first)
3. Package
2
Package shape Width of plastic Pitch of pin
SOP20 7.62mm 300mil 1.27mm 50mil
DIP20 7.62mm 300mil 2.54mm 100mil
Instruction of package
Small outline package of 20-pin
Dual in-line package of 20-pin
Ordering type
CH450H
CH450K
4. Pins
Pin No.
12
5
10, 11, 13,
14, 15, 16,
17, 18
20, 1, 2,
6, 7, 8
4
3
9
19
Pin Name
VCC
GND
SEG0SEG7
DIG2DIG7
SDA
SCL
RSTH
INT#
Pin Type
POWER
POWER
Tri-station
output input
OUT
With
pull-up
drain open
output input
IN
OUT
With
pull-up
internal
drain open
output
Pin Description
Positive power, the persistent current is no less than 100mA
Public ground, the persistent current is no less than 100mA
Segment drive of numeric LEDs, high-level active,
keyboard scan input, high-level active, with pull-down
resistor
Word drive of numeric LEDs, low-level active, keyboard
scan output, high-level active
Data input and output of two wires serial interface
Data clock of two wires serial interface, with pull-up
resistor internal
Power up reset output, high-level active
Keyboard interrupt output, low-level active with
5. Function description
5.1. General description
The data in this DataSheet has three types. Binary numbers are followed by a B. Hexadecimal
numbers are followed by an H. Numbers without annotations are decimals. X stands for any value.
MCU (DSP, microprocessor and other controller) controls CH450 chip via two wires serial interface.
Numeric LEDs display drive and keyboard scan control are independence in CH450. MCU can start, close
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CH450 Даташит, Описание, Даташиты
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The DataSheet of CH450 (the first)
3
and set the two functions through operation command. The two wire serial interface in CH450 is achieved by
hardware. MCU can operate with high-speed via serial interface frequently, and has no influence on the
CH450S efficiency.
5.2. Display drive
CH450 adopts dynamically scan drive for number LED and LEDs, the sequence is from DIG2 to DIG7.
When one of the pins draws current, the other pins dont draw current. In the internal of CH450 has current
drive layer, directly drive 0.5 inch to 1 inch common cathode number LED, SEG6~SEG0 are respectively
corresponding to segment G~A, the SEG7 is corresponding to radix point. Word drive pins DIG7~DIG2 are
respectively connect to six number LEDscathode. CH450 can connect to LED which is 8×6 matrix or
forty-eight LEDs. Or connect to invertor drivers outside to support common anode number LED, connect
great power pipe to support large size number LEDs.
In the inner of CH450 has six eight-bits digital registers, they are used to save six word data,
respectively corresponding to six number LEDs or six groups LEDs while each group has eight LEDs. The
bit 7 to bit 0 of word data in digital register are respectively corresponding to radix point and segment G to A.
for the LED matrix, the data bit of each word data is only corresponding to one LED. When data bit is 1, the
relevant segment of number LED or LED will light; when data bit is 0, the relevant segment of number LED
or LED will distinguish. For example, the bit 0 of the third digital register is 1, then the segment A of the
third number LED will light.
The following is segment name of number LED.
5.3. Keyboard scan
The keyboard function of CH450 supports 8×6 matrix 48-key keyboard. During the keyboard scan
period, DIG7~DIG2 used to output row scan,SEG7~SEG0 with pull-down resistor used to input line scan.
CH450 inserts keyboard scan regularly during display drive scan. During keyboard scan period,
DIG7~DIG2 accords DIG2 to DIG7 in turn output high-level, and other pin output low-level; the output of
SEG7~SEG0 are forbidden, when there is no key is pressed, SEG7~SEG0 are low-level; when there is key is
pressed, such as DIG3 and SEG4 are pressed, then DIG output high- level and SEG4 checked high-level. In
order to avoid error code, Ch450 will scan twice, only when result is the same, the key-press is valid. When
CH450 has checked valid key-press, record the key-press code, and INT# generates valid keyboard interrupt
which active with low-level, and the MCU can read key-press code via serial. CH450 cant generate any
key-press interrupt before checking new valid key-press. CH450 cant support press two or more keys at the
same time. If two or more keys are pressed, the smaller code is in priority.
The key-press code is 8-bit providing by CH450, bit2~bit0 are row scan code, bit5~bit3 is line scan
code, bit6 is status code (the pressed key is 1, or is 0). For example, the key connect DIG3 with SEG4 is
pressed, then the code is 1100011B or 63H, when the key is released, the code is 0100011B or 23H (maybe
is other value, but it is less than 40H). The row scan code is 011B responding to DIG3, the line scan code is
100B responding to SEG4. MCU can read key-press code at any time. Generally, MCU reads key-press code
after CH450 has checked the valid key-press, and the bit 6 always is 1. Additional, if want to know when the
key-press is released, MCU can read the key-press code regularly via query mode, until the key-press bit6 is
0.
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