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参数资料
| 型号： | MAX1368ECM+ |
| 厂商： | Maxim Integrated |
| 文件页数： | 32/36页 |
| 文件大小： | 0K |
| 描述： | IC PANEL METER 3.5 DIG 48LQFP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 250 |
| 显示器类型： | LED |
| 配置： | 7 段显示 |
| 接口： | 串行 |
| 数字或字符： | A/D，3.5 位数字 |
| 电源电压： | 2.7 V ~ 5.25 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 48-LQFP |
| 供应商设备封装： | 48-LQFP（7x7） |
| 包装： | 托盘 |
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Microcontroller-Interface, 4.5-/3.5-Digit Panel
Meters with 4–20mA Output
R ISET values below 25k ? increase the I SEG . However,
the internal current-limit circuit limits the I SEG to less than
30mA. At higher I SEG values, proper operation of the
device is not guaranteed. In addition, the power dissipat-
ed may exceed the package power-dissipation limit.
Choosing Supply Voltage to Minimize
Power Dissipation
The MAX1366/MAX1368 drive a peak current of 25.5mA
into LEDs with a 2.2V forward-voltage drop when operat-
ed from a supply voltage of at least 3.0V. Therefore, the
minimum voltage drop across the internal LED drivers is
0.8V (3.0V - 2.2V = 0.8V). The MAX1366/MAX1368 sink
when the outputs are operating and the LED segment
drivers are at full current (8 x 25.5mA = 204mA). For a
3.3V supply, the MAX1366/MAX1368 dissipate 224.4mW
((3.3V - 2.2V) x 204 = 224.4mW). If a higher supply volt-
age is used, the driver absorbs a higher voltage, and the
driver ’s power dissipation increases accordingly.
However, if the LEDs used have a higher forward-voltage
drop than 2.2V, the supply voltage must be raised
accordingly to ensure that the driver always has at least
0.8V headroom. For an LEDV supply voltage of 2.7V, the
maximum LED forward voltage is 1.9V to ensure 0.8V dri-
ver headroom. The voltage drop across the drivers with
a nominal +5V supply (5.0V - 2.2V = 2.8V) is almost
three times the drop across the drivers with a nominal
3.3V supply (3.3V - 2.2V = 1.1V). Therefore, the driver’s
power dissipation increases three times. The power dis-
sipation in the part causes the junction temperature to
rise accordingly. In the high ambient temperature case,
the total junction temperature may be very high (>
+125°C). At higher junction temperatures, the ADC per-
formance degrades. To ensure the dissipation limit for
the MAX1366/MAX1368 is not exceeded and the ADC
performance is not degraded; a diode can be inserted
between the power supply and LEDV.
Selecting Depletion-Mode FET
An external depletion-mode FET (DMOS) works in con-
junction with the regulator circuit to supply the V/I con-
verter with loop power. REG_FORCE regulates the gate
of the DMOS so that the drain voltage is 5.2V (typ) and
allows the 4–20mA (0 to 16mA) loop to be directly pow-
ered from a 7V to 30V supply. DMOS I DS consists of the
current output at 4-20OUT, a 4mA offset current, and
1mA (typ) consumed by the V/I converter.
For offset-enabled mode (EN_I = 1):
I DS = I 4-20OUT + 4mA + 1mA
For offset-disabled mode (EN_I = 0):
I DS = I 4-20OUT + 1mA
where I DS is the current in the DMOS.
Table 9 provides the FET characteristics for selecting
an external DMOS transistor. The DN25D FET transistor
from Supertex meets all the requirements of Table 7.
Other suitable transistors include ND2020L and
ND2410L from Siliconix.
Connect a 0.1μF capacitor between CMP and
REG_FORCE to ensure stable regulator compensation.
Definitions
Integral Nonlinearity (INL)
INL is the deviation of the values on an actual transfer
function from a straight line. This straight line is either a
best-straight-line fit or a line drawn between the end
points of the transfer function, once offset and gain
errors have been nullified. INL for the MAX1366/
MAX1368 is measured using the end-point method.
Differential Nonlinearity (DNL)
DNL is the difference between an actual step width and
the ideal value of ±1 LSB. A DNL error specification of
less than ±1 LSB guarantees no missing codes and a
monotonic transfer function.
Rollover Error
Rollover error is defined as the absolute-value differ-
ence between a near positive full-scale reading and
near negative full-scale reading. Rollover error is tested
by applying a full-scale positive voltage, swapping
AIN+ and AIN-, and adding the results.
Zero-Input Reading
Ideally, with AIN+ connected to AIN-, the MAX1366/
MAX1368 LED displays zero. Zero-input reading is the
measured deviation from the ideal zero and the actual
measured point.
Gain Error
Gain error is the amount of deviation between the mea-
sured full-scale transition point and the ideal full-scale
transition point.
Common-Mode Rejection (CMR)
CMR is the ability of a device to reject a signal that is
common to both input terminals. The common-mode
signal can be either an AC or a DC signal or a combi-
nation of the two. CMR is often expressed in decibels.
Normal-Mode 50Hz and 60Hz Rejection
(Simultaneously)
Normal-mode rejection is a measure of how much output
changes when 50Hz and 60Hz signals are injected into
only one of the differential inputs. The MAX1366/
MAX1368 sigma-delta converter uses its internal digital
filter to provide normal-mode rejection to both 50Hz and
60Hz power-line frequencies simultaneously.
32
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1368ECM+ | 功能描述:LED显示驱动器 Stand-Alone 3.5Digit Panel Meters RoHS:否 制造商:Micrel 数位数量:5 片段数量: 安装风格:SMD/SMT 封装 / 箱体:PLCC-44 工作电源电压:4.75 V to 11 V 最大电源电流:10 mA 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装:Tube |
| MAX1368ECM+T | 功能描述:LED显示驱动器 Stand-Alone 3.5Digit Panel Meters RoHS:否 制造商:Micrel 数位数量:5 片段数量: 安装风格:SMD/SMT 封装 / 箱体:PLCC-44 工作电源电压:4.75 V to 11 V 最大电源电流:10 mA 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装:Tube |
| MAX1368ECM-T | 功能描述:LED显示驱动器 RoHS:否 制造商:Micrel 数位数量:5 片段数量: 安装风格:SMD/SMT 封装 / 箱体:PLCC-44 工作电源电压:4.75 V to 11 V 最大电源电流:10 mA 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装:Tube |
| MAX136C/D | 功能描述:模数转换器 - ADC RoHS:否 制造商:Texas Instruments 通道数量:2 结构:Sigma-Delta 转换速率:125 SPs to 8 KSPs 分辨率:24 bit 输入类型:Differential 信噪比:107 dB 接口类型:SPI 工作电源电压:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-32 |
| MAX136CJL | 功能描述:模数转换器 - ADC RoHS:否 制造商:Texas Instruments 通道数量:2 结构:Sigma-Delta 转换速率:125 SPs to 8 KSPs 分辨率:24 bit 输入类型:Differential 信噪比:107 dB 接口类型:SPI 工作电源电压:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-32 |
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