参数资料
型号: MCP1790T-5002E/EB
厂商: Microchip Technology
文件页数: 15/34页
文件大小: 0K
描述: IC REG LDO 5V 70MA 3DDPAK
标准包装: 750
稳压器拓扑结构: 正,固定式
输出电压: 5V
输入电压: 6 V ~ 30 V
电压 - 压降(标准): 0.7V @ 70mA
稳压器数量: 1
电流 - 输出: 70mA(最小)
工作温度: -40°C ~ 125°C
安装类型: 表面贴装
封装/外壳: TO-263-4,D²Pak(3 引线+接片),TO-263AA
供应商设备封装: DDPAK/TO-263-3
包装: 带卷 (TR)
其它名称: MCP1790T-5002E/EBTR
MCP1790/MCP1791
4.5
Shutdown (SHDN)
4.6
Low Voltage Shutdown
The MCP1791 has a Shutdown (SHDN) input signal
that enables or disables the regulator output voltage.
When the SHDN input signal is greater than 2.40V, the
regulator output voltage is enabled. Note that the
regulator output may still be disabled by the
undervoltage lockout incorporated within the V IN
circuitry.
The value of the SHDN signal to put the regulator into
Shutdown mode is ≤ 0.8V. The SHDN pin is pulled low
by an internal resistor. If the SHDN pin is left floating,
the internal pull-down resistor will put the regulator into
shutdown mode.
When the SHDN input signal is pulled to a logic-low, the
PWRGD output signal will also go low and the regulator
The MCP1790/MCP1791 incorporates a Low Voltage
Shutdown circuit that turns off the output of the
regulator whenever the input voltage, V IN , is below the
specified turn off voltage, V OFF . When the input voltage
(V B ) drops below the differential needed to provide
stable regulation, the output voltage (V REG ) shall track
the input down to approximately +4.00V. The regulator
will turn off the output at this point.
The output will turn on when V IN rises above the V ON
value specified in the data sheet. This feature is
independent of the Shutdown input signal (SHDN) that
is provided for external regulator control. If the SHDN
input signal is active (LOW), then the output of the
regulator shall be disabled regardless of input voltage.
will enter a low quiescent current state where the
typical quiescent current is 10 μA. There is a short time
TABLE 4-1:
SHUTDOWN LOGIC
delay (approximately 400 ns) when the SHDN input
signal transitions from high-to-low to p reven t signal
noise from disabling the regulator. The SHDN pin will
ignore low-going pulses that are up to 400 ns in pulse
width. If the SHDN input is pulled low for more than
400 ns, the regulator will enter Shutdown mode. This
small bit of filtering helps to reject any system noise
V IN
< V OFF
< V OFF
> V ON
> V ON
SHDN
L
H
L
H
V OUT
OFF
OFF
OFF
ON
spikes on the SHDN input signal.
On the rising edge of the SHDN input, the shutdown
4.7
Output Capacitor
circuitry will have a 100 μs delay before allowing the
regulator output to turn on. This delay helps to reject
any false turn-on signals or noise on the SHDN input
signal. After the 100 μs delay, the regulator will start
charging the output capacitor as the regulator output
voltage rises from 0V to its final regulated value. The
charging current will be limited by the short circuit
current value of the device. If the SHDN input signal is
pulled low during the 100 μs delay period, the timer will
be reset and the delay time will start over again on the
next rising edge of the SHDN input. The total time from
the SHDN input going high (turn-on) to the regulator
output being in regulation shall typically be 200 μs
(100 μs + 100 μs) for a C LOAD = 1.0 μF.
The MCP1790/MCP1791 requires a minimum output
capacitance of 1 μF tantalum or electrolytic
capacitance. The minimum value for ceramic
capacitors is 4.7 μF. The regulator is stable for all three
types of capacitors from 4.7 μF to 1000 μF (see
Figure 4-3 ). The MCP1790/MCP1791 regulator may
be used with a 1 μF ceramic output capacitor if a
0.300 Ω resistor is placed in series with the capacitor.
The low ESR and corresponding pole of the ceramic
capacitor causes the instability below 4.7 μF.
The Equivalent Series Resistance (ESR) of the output
capacitor must be no greater than 3 ohms. The output
capacitor should be located as close to the regulator
output as is practical. Ceramic materials X7R and X5R
have low temperature coefficients and are
100 μs
TOR
100 μs
C LOAD C HARGING T IME
400 ns (typ)
recommended because of their size, cost and
environmental robustness qualities.
SHDN
V OUT
C LOAD = 1.0 μF
FIGURE 4-2:
Diagram.
Shutdown Input Timing
? 2010 Microchip Technology Inc.
DS22075B-page 15
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MCP1791-3002E/DC 功能描述:低压差稳压器 - LDO HI VLTG LDO 50 mA RoHS:否 制造商:Texas Instruments 最大输入电压:36 V 输出电压:1.4 V to 20.5 V 回动电压(最大值):307 mV 输出电流:1 A 负载调节:0.3 % 输出端数量: 输出类型:Fixed 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-20
MCP1791-3002E/ET 功能描述:低压差稳压器 - LDO HI VLTG LDO 50 mA RoHS:否 制造商:Texas Instruments 最大输入电压:36 V 输出电压:1.4 V to 20.5 V 回动电压(最大值):307 mV 输出电流:1 A 负载调节:0.3 % 输出端数量: 输出类型:Fixed 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-20
MCP1791-3302E/DC 功能描述:低压差稳压器 - LDO HI VLTG LDO 50 mA RoHS:否 制造商:Texas Instruments 最大输入电压:36 V 输出电压:1.4 V to 20.5 V 回动电压(最大值):307 mV 输出电流:1 A 负载调节:0.3 % 输出端数量: 输出类型:Fixed 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-20
MCP1791-3302E/ET 功能描述:低压差稳压器 - LDO HI VLTG LDO 50 mA RoHS:否 制造商:Texas Instruments 最大输入电压:36 V 输出电压:1.4 V to 20.5 V 回动电压(最大值):307 mV 输出电流:1 A 负载调节:0.3 % 输出端数量: 输出类型:Fixed 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-20
MCP1791-5002E/DC 功能描述:低压差稳压器 - LDO HI VLTG LDO 50 mA RoHS:否 制造商:Texas Instruments 最大输入电压:36 V 输出电压:1.4 V to 20.5 V 回动电压(最大值):307 mV 输出电流:1 A 负载调节:0.3 % 输出端数量: 输出类型:Fixed 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-20