參數(shù)資料
型號(hào)： MAX7221
廠商： Maxim Integrated Products, Inc.
英文描述： Dual 4-Input Positive-AND Gates 14-CDIP -55 to 125
中文描述： 串行接口、8位、LED顯示驅(qū)動(dòng)器
文件頁(yè)數(shù)： 10/16頁(yè)
文件大?。?/td> 186K
代理商： MAX7221
M
If the scan-limit register is set for three digits or less,
individual digit drivers will dissipate excessive amounts
of power. Consequently, the value of the R
SET
resistor
must be adjusted according to the number of digits dis-
played, to limit individual digit driver power dissipation.
Table 9 lists the number of digits displayed and the
corresponding maximum recommended segment cur-
rent when the digit drivers are used.
Display-T est Register
The display-test register operates in two modes: normal
and display test. Display-test mode turns all LEDs on
by overriding, but not altering, all controls and digit reg-
isters (including the shutdown register). In display-test
mode, 8 digits are scanned and the duty cycle is 31/32
(15/16 for MAX7221). Table 10 lists the display-test reg-
ister format.
No-Op Register
The no-op register is used when cascading MAX7219s
or MAX7221s. Connect all devices’ LOAD/
CS
inputs
together and connect DOUT to DIN on adjacent
devices. DOUT is a CMOS logic-level output that easily
drives DIN of successively cascaded parts. (Refer to
the Serial Addressing Modes section for detailed infor-
mation on serial input/output timing.) For example, if
four MAX7219s are cascaded, then to write to the
fourth chip, sent the desired 16-bit word, followed by
three no-op codes (hex XX0X, see Table 2). When
LOAD/
CS
goes high, data is latched in all devices. The
first three chips receive no-op commands, and the
fourth receives the intended data.
__________Applic ations Information
S upply Bypassing and Wiring
To minimize power-supply ripple due to the peak digit
driver currents, connect a 10μF electrolytic and a 0.1μF
ceramic capacitor between V+ and GND as close to
the device as possible. The MAX7219/MAX7221 should
be placed in close proximity to the LED display, and
connections should be kept as short as possible to
minimize the effects of wiring inductance and electro-
magnetic interference. Also, both GND pins must be
connected to ground.
S elec ting R
S ET
Resistor and
Using External Drivers
The current per segment is approximately 100 times
the current in ISET. To select R
SET
, see Table 11. The
MAX7219/MAX7221’s maximum recommended seg-
ment current is 40mA. For segment current levels
above these levels, external digit drivers will be need-
ed. In this application, the MAX7219/MAX7221 serve
only as controllers for other high-current drivers or tran-
sistors. Therefore, to conserve power, use R
SET
= 47k
when using external current sources as segment dri-
vers.
The example in Figure 2 uses the MAX7219/MAX7221’s
segment drivers, a MAX394 single-pole double-throw
analog switch, and external transistors to drive 2.3”
AND2307SLC common-cathode displays. The 5.6V
zener diode has been added in series with the decimal
point LED because the decimal point LED forward volt-
age is typically 4.2V. For all other segments the LED
forward voltage is typically 8V. Since external transis-
tors are used to sink current (DIG 0 and DIG 1 are used
as logic switches), peak segment currents of 45mA are
allowed even though only two digits are displayed. In
applications where the MAX7219/MAX7221’s digit dri-
vers are used to sink current and fewer than four digits
are displayed, Table 9 specifies the maximum allow-
able segment current. R
SET
must be selected accord-
ingly (Table 11).
Refer to the Power Dissipation section of the Absolute
Maximum Ratings to calculate acceptable limits for
ambient temperature, segment current, and the LED
forward-voltage drop.
S erially Interfac ed, 8-Digit LED Display Drivers
10
______________________________________________________________________________________
Table 9. Maximum Segment Current for
1-, 2-, or 3-Digit Displays
Table 10. Display-Test Register Format
(Address (Hex) = XF)
10
20
30
2
3
MAXIMUM SEGMENT
CURRENT
(mA)
1
NUMBER OF DIGITS
DISPLAYED
X
X
Normal
Operation
D6
X
X
Display Test
Mode
D4
X
X
D5
X
X
D2
X
0
REGISTER DATA
D0
X
X
X
D1
X
D3
1
X
D7
MODE
Note: The MAX7219/MAX7221 remain in display-test mode
(all LEDs on) until the display-test register is reconfigured
for normal operation.
相關(guān)PDF資料
PDF描述
MAX7221CWG Dual 4-Input Positive-AND Gates 14-CFP -55 to 125
MAX7221ERG Dual 4-Input Positive-AND Gates 14-CDIP -55 to 125
MAX7221EWG Dual 4-Input Positive-AND Gates 20-LCCC -55 to 125
MAX7221CNG Serially Interfaced, 8-Digit LED Display Drivers
MAX7219CWG Serially Interfaced, 8-Digit LED Display Drivers
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MAX7221C/D 制造商:MAXIM 制造商全稱(chēng):Maxim Integrated Products 功能描述:Serially Interfaced, 8-Digit LED Display Drivers
MAX7221CNG 功能描述:LED顯示驅(qū)動(dòng)器 8-Digit LED Display Driver RoHS:否 制造商:Micrel 數(shù)位數(shù)量:5 片段數(shù)量: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PLCC-44 工作電源電壓:4.75 V to 11 V 最大電源電流:10 mA 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝:Tube
MAX7221CNG+ 功能描述:LED顯示驅(qū)動(dòng)器 8-Digit LED Display Driver RoHS:否 制造商:Micrel 數(shù)位數(shù)量:5 片段數(shù)量: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PLCC-44 工作電源電壓:4.75 V to 11 V 最大電源電流:10 mA 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝:Tube
MAX7221CNG+ 制造商:Maxim Integrated Products 功能描述:DRIVER LED DISPLAY 8DIGIT 24DIP 制造商:Maxim Integrated Products 功能描述:DRIVER, LED DISPLAY, 8DIGIT, 24DIP 制造商:Maxim Integrated Products 功能描述:DRIVER, LED DISPLAY, 8DIGIT, 24DIP; Topology:Common Cathode; No. of Outputs:16; Output Current:320mA; Output Voltage:4.5V; Driver Case Style:DIP; Input Voltage Min:4V; Input Voltage Max:5.5V; Dimming Control Type:Analogue, Digital; ;RoHS Compliant: Yes
MAX7221CWG 功能描述:LED顯示驅(qū)動(dòng)器 Integrated Circuits (ICs) RoHS:否 制造商:Micrel 數(shù)位數(shù)量:5 片段數(shù)量: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PLCC-44 工作電源電壓:4.75 V to 11 V 最大電源電流:10 mA 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝:Tube
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