- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄383583 > MCP1257-EMF (Microchip Technology Inc.) Regulated 3.3V, Low-Ripple Charge Pump with Low- Operating Current SLEEP Mode or BYPASS Mode PDF資料下載
參數(shù)資料
| 型號： | MCP1257-EMF |
| 廠商： | Microchip Technology Inc. |
| 英文描述： | Regulated 3.3V, Low-Ripple Charge Pump with Low- Operating Current SLEEP Mode or BYPASS Mode |
| 中文描述： | 3.3V的穩(wěn)壓，低紋波充電泵具有低工作電流睡眠模式或旁路模式 |
| 文件頁數(shù)： | 13/24頁 |
| 文件大?。?/td> | 1183K |
| 代理商： | MCP1257-EMF |
2006 Microchip Technology Inc.
DS21989A-page 13
MCP1256/7/8/9
4.6
Power-Good Output (PGOOD)
For the MCP1256/8 devices, the PGOOD output is an
open-drain output that sinks current when the regulator
output voltage falls below 0.93V
OUT
(typical). If the reg-
ulator output voltage falls below 0.93V
OUT
(typical) for
less than 200
μ
s and then recovers, glitch immunity cir-
cuits prevent the PGOOD signal from transitioning low.
A 10 k
Ω
to 1 M
Ω
pull-up resistor from PGOOD to V
OUT
may be used to provide a logic output. If not used,
connect PGOOD to GND or leave unconnected.
PGOOD is high impedance when the output voltage is
in regulation. A logic low is asserted when the output
falls 7% (typical) below the nominal value. The PGOOD
output remains low until V
OUT
is within 3% (typical) of
its nominal value. On start-up, this pin indicates when
the output voltage reaches its final value. PGOOD is
high impedance when SHDN is low or when BYPASS
is low (MCP1258).
4.7
Low-Battery Output (LBO)
For the MCP1257/9 devices, the LBO output is an
open-drain output that sinks current when the input
voltage falls below a preset threshold. If the input volt-
age falls below the preset threshold for less than
200
μ
s and then recovers, glitch immunity circuits pre-
vent the LBO signal from transitioning low. A 10 k
Ω
to
1 M
Ω
pull-up resistor from LBO to V
OUT
may be used
to provide a logic output. If not used, connect LBO to
GND or leave unconnected.
LBO is high impedance when the input voltage is above
the low-battery threshold voltage. A logic low is
asserted when the input falls below the low-battery
threshold voltage. The LBO output remains low until
V
IN
is above the low-battery threshold voltage plus the
low-battery hysteresis voltage. LBO is high impedance
when SHDN is low or when BYPASS is low
(MCP1259).
4.8
Soft-Start and Short-Circuit
Protection
The MCP1256/7/8/9 devices feature fold back short-
circuit protection. This circuitry provides an internal
soft-start function by limiting inrush current during
startup and also limits the output current to 150 mA
(typical), if the output is short-circuited to GND. The
internal soft-start circuitry requires approximately
175
μ
s, typical, from either initial power-up, release
from Shutdown, or release from BYPASS (MCP1258/9)
for the output voltage to be in regulation.
4.9
Thermal Shutdown
The MCP1256/7/8/9 devices feature thermal shutdown
with temperature hysteresis. When the die temperature
exceeds 160°C, the device shuts down. When the die
cools by 15°C, the MCP1256/7/8/9 automatically turns
back on again. If high die temperature is caused by out-
put overload and the load is not removed, the device
will turn on and off resulting in a pulsed output.
5.0
APPLICATIONS
5.1
Capacitor Selection
The style and value of capacitors used with the
MCP1256/7/8/9 family determine several important
parameters, such as output voltage ripple and charge
pump strength. To minimize noise and ripple, it is rec-
ommended that low ESR (0.1
Ω
) capacitors be used for
both C
IN
and C
OUT
. These capacitors should be
ceramic and should be 10
μ
F or higher for optimum
performance.
If the source impedance to V
IN
is very low, up to several
megahertz, C
IN
may not be required. Alternatively, a
somewhat smaller value of C
IN
may be substituted for
the recommended 10
μ
F, but will not be as effective in
preventing ripple on the V
IN
pin.
The value of C
OUT
controls the amount of output volt-
age ripple present on V
OUT
. Increasing the size of
C
OUT
will reduce output ripple at the expense of a
slower turn-on time from shutdown and a higher inrush
current.
The flying capacitors (C
1
and C
2
) control the strength
of the charge pump and in order to achieve the maxi-
mum rated output current (100 mA), it is necessary to
have at least 1
μ
F of capacitance for the flying capaci-
tor. A smaller flying capacitor delivers less charge per
clock cycle to the output capacitor resulting in lower
available output current.
5.2
PCB Layout Issues
The MCP1256/7/8/9 devices transfer charge at high
switching frequencies producing fast, high peak, tran-
sient currents. As a result, any stray inductance in the
component layout will produce unwanted noise in the
system. Proper board layout techniques are required to
ensure optimum performance.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MCP1257-EUN | Regulated 3.3V, Low-Ripple Charge Pump with Low- Operating Current SLEEP Mode or BYPASS Mode |
| MCP1257T-EMF | Regulated 3.3V, Low-Ripple Charge Pump with Low- Operating Current SLEEP Mode or BYPASS Mode |
| MCP1257T-EUN | Regulated 3.3V, Low-Ripple Charge Pump with Low- Operating Current SLEEP Mode or BYPASS Mode |
| MCP1258 | Regulated 3.3V, Low-Ripple Charge Pump with Low- Operating Current SLEEP Mode or BYPASS Mode |
| MCP1258-EMF | Regulated 3.3V, Low-Ripple Charge Pump with Low- Operating Current SLEEP Mode or BYPASS Mode |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MCP1257-EUN | 制造商:MICROCHIP 制造商全稱:Microchip Technology 功能描述:Regulated 3.3V, Low-Ripple Charge Pump with Low- Operating Current SLEEP Mode or BYPASS Mode |
| MCP1257T-E/MF | 功能描述:電荷泵 Frac Charge Pump w/ LBO and Sleep RoHS:否 制造商:Maxim Integrated 功能:Inverting, Step Up 輸出電壓:- 1.5 V to - 5.5 V, 3 V to 11 V 輸出電流:100 mA 電源電流:1 mA 最大工作溫度:+ 70 C 封裝 / 箱體:SOIC-8 Narrow 封裝:Tube |
| MCP1257T-E/UN | 功能描述:電荷泵 Frac Charge Pump w/ LBO and Sleep RoHS:否 制造商:Maxim Integrated 功能:Inverting, Step Up 輸出電壓:- 1.5 V to - 5.5 V, 3 V to 11 V 輸出電流:100 mA 電源電流:1 mA 最大工作溫度:+ 70 C 封裝 / 箱體:SOIC-8 Narrow 封裝:Tube |
| MCP1257T-EMF | 制造商:MICROCHIP 制造商全稱:Microchip Technology 功能描述:Regulated 3.3V, Low-Ripple Charge Pump with Low- Operating Current SLEEP Mode or BYPASS Mode |
| MCP1257T-EUN | 制造商:MICROCHIP 制造商全稱:Microchip Technology 功能描述:Regulated 3.3V, Low-Ripple Charge Pump with Low- Operating Current SLEEP Mode or BYPASS Mode |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。