參數(shù)資料
型號: MCP1726
廠商: Microchip Technology Inc.
元件分類: 基準(zhǔn)電壓源/電流源
英文描述: 1A, Low Voltage, Low Quiescent Current LDO Regulator
中文描述: 1A中,低電壓,低靜態(tài)電流LDO穩(wěn)壓器
文件頁數(shù): 15/30頁
文件大?。?/td> 431K
代理商: MCP1726
2005 Microchip Technology Inc.
DS21936B-page 15
MCP1726
4.4
Input Capacitor
Low input source impedance is necessary for the LDO
output to operate properly. When operating from
batteries, or in applications with long lead length
(> 10 inches) between the input source and the LDO,
some input capacitance is recommended. A minimum
of 1.0 μF to 4.7 μF is recommended for most applica-
tions.
For applications that have output step load
requirements, the input capacitance of the LDO is very
important. The input capacitance provides the LDO
with a good local low-impedance source to pull the
transient currents from in order to respond quickly to
the output load step. For good step response perfor-
mance, the input capacitor should be of equivalent (or
higher) value than the output capacitor. The capacitor
should be placed as close to the input of the LDO as is
practical. Larger input capacitors will also help reduce
any high-frequency noise on the input and output of the
LDO and reduce the effects of any inductance that
exists between the input source voltage and the input
capacitance of the LDO.
4.5
Power Good Output (PWRGD)
The PWRGD output is used to indicate when the output
voltage of the LDO is within 92% (typical value, see the
Electrical Characteristics table for Min/Max specs) of its
nominal regulation value.
As the output voltage of the LDO rises, the PWRGD
output will be held low until the output voltage has
exceeded the power good threshold plus the hysteresis
value. Once this threshold has been exceeded, the
power good time delay is started (shown as T
PG
in the
Electrical Characteristics table). The power good time
delay is adjustable via the C
DELAY
pin of the LDO (see
Section 4.6 “C
DELAY
Input”
). By placing a capacitor
from the C
DELAY
pin to ground, the power good time
delay can be adjusted from 200 μs (no capacitance) to
300 ms (0.1 μF capacitor). After the time delay period,
the PWRGD output will go high, indicating that the out-
put voltage is stable and within regulation limits.
If the output voltage of the LDO falls below the power
good threshold, the power good output will transition
low. The power good circuitry has a 170 μs delay when
detecting a falling output voltage, which helps to
increase noise immunity of the power good output and
avoid false triggering of the power good output during
fast output transients. See Figure 4-2 for power good
timing characteristics.
When the LDO is put into Shutdown mode using the
SHDN input, the power good output is pulled low
immediately, indicating that the output voltage will be
out of regulation. The timing diagram for the power
good output when using the shutdown input is shown in
Figure 4-3.
The power good output is an open-drain output that can
be pulled up to any voltage that is equal to or less than
the LDO input voltage. This output is capable of sinking
1.2 mA (V
PWRGD
< 0.4V maximum).
FIGURE 4-2:
Power Good Timing.
FIGURE 4-3:
Shutdown.
Power Good Timing from
4.6
C
DELAY
Input
The C
DELAY
input is used to provide the power-up
delay timing for the power good output, as discussed in
the previous section. By adding a capacitor from the
C
DELAY
pin to ground, the PWRGD power-up time
delay can be adjusted from 200 μs (no capacitance on
C
DELAY
) to 300 ms (0.1 μF of capacitance on C
DELAY
).
See the Electrical Characteristics table for C
DELAY
timing tolerances.
T
PG
T
VDET_PWRGD
V
PWRGD_TH
V
OUT
PWRGD
V
OL
V
OH
V
IN
SHDN
V
OUT
30 ms
70 ms
T
OR
PWRGD
T
PG
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參數(shù)描述
MCP1726-0802E/MF 功能描述:低壓差穩(wěn)壓器 - LDO 1A .8V Vout Extended Temp RoHS:否 制造商:Texas Instruments 最大輸入電壓:36 V 輸出電壓:1.4 V to 20.5 V 回動電壓(最大值):307 mV 輸出電流:1 A 負(fù)載調(diào)節(jié):0.3 % 輸出端數(shù)量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-20
MCP1726-0802E/SN 功能描述:低壓差穩(wěn)壓器 - LDO 1A .8V Vout Extended Temp RoHS:否 制造商:Texas Instruments 最大輸入電壓:36 V 輸出電壓:1.4 V to 20.5 V 回動電壓(最大值):307 mV 輸出電流:1 A 負(fù)載調(diào)節(jié):0.3 % 輸出端數(shù)量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-20
MCP1726-1202E/MF 功能描述:低壓差穩(wěn)壓器 - LDO 1A 1.2V Vout Extended Temp RoHS:否 制造商:Texas Instruments 最大輸入電壓:36 V 輸出電壓:1.4 V to 20.5 V 回動電壓(最大值):307 mV 輸出電流:1 A 負(fù)載調(diào)節(jié):0.3 % 輸出端數(shù)量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-20
MCP1726-1202E/SN 功能描述:低壓差穩(wěn)壓器 - LDO 1A 1.2V Vout Extended Temp RoHS:否 制造商:Texas Instruments 最大輸入電壓:36 V 輸出電壓:1.4 V to 20.5 V 回動電壓(最大值):307 mV 輸出電流:1 A 負(fù)載調(diào)節(jié):0.3 % 輸出端數(shù)量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-20
MCP1726-1802E/MF 功能描述:低壓差穩(wěn)壓器 - LDO 1A 1.8V Vout Extended Temp RoHS:否 制造商:Texas Instruments 最大輸入電壓:36 V 輸出電壓:1.4 V to 20.5 V 回動電壓(最大值):307 mV 輸出電流:1 A 負(fù)載調(diào)節(jié):0.3 % 輸出端數(shù)量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-20