- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄385505 > LTC1751-5 (Linear Technology Corporation) Micropower, Regulated Charge Pump DC/DC Converters PDF資料下載
參數(shù)資料
| 型號(hào)： | LTC1751-5 |
| 廠商： | Linear Technology Corporation |
| 英文描述： | Micropower, Regulated Charge Pump DC/DC Converters |
| 中文描述： | 微功耗，穩(wěn)壓電荷泵DC / DC轉(zhuǎn)換器 |
| 文件頁數(shù)： | 9/12頁 |
| 文件大小： | 211K |
| 代理商： | LTC1751-5 |
9
LTC1751/LTC1751-3.3/LTC1751-5
Note that when using a larger output capacitor the mini-
mum turn-on time of the device will increase.
Soft-Start
The LTC1751 family has built-in soft-start circuitry to
prevent excessive current flow at V
IN
during start-up. The
soft-start time is programmed by the value of the capacitor
at the SS pin. Typically a 2
μ
A current is forced out of SS
causing a ramp voltage on the SS pin. The regulation loop
follows this ramp voltage until the output reaches the
correct regulation level. SS is automatically pulled to
ground whenever SHDN is low. The typical rise time is
given by the expression:
t
r
= 0.6ms/nF C
SS
For example, with a 4.7nF capacitor the 10% to 90% rise
time will be approximately 2.8ms. If the output charge
storage capacitor is 10
μ
F, then the average output current
for an LTC1751-5 will be 4V/2.8ms 10
μ
F or 14mA, giving
28mA at the V
IN
pin.
The soft-start feature is optional. If there is no capacitor
on SS, the output voltage of the LTC1751 will ramp up as
quickly as possible. The start-up time will depend on
APPLICATIOU
There are several ways to reduce output voltage ripple.
For applications requiring V
IN
to exceed 3.3V or for
applications requiring <100mV of peak-to-peak ripple, a
larger C
OUT
capacitor (22
μ
F or greater) is recommended.
A larger capacitor will reduce both the low and high
frequency ripple due to the lower charging and discharg-
ing slew rates as well as the lower ESR typically found
with higher value (larger case size) capacitors. A low ESR
ceramic output capacitor will minimize the high fre-
quency ripple, but will not reduce the low frequency
ripple unless a high capacitance value is used. An R-C
filter may also be used to reduce high frequency voltages
spikes (see Figure 1).
W
U
U
various parameters such as temperature, output loading,
charge pump and flying capacitor values and input
voltage.
PGOOD and Undervoltage Detection
The PGOOD pin on the LTC1751-3.3/LTC1751-5 performs
two functions. On start-up, it indicates when the output
has reached its final regulation level. After start-up, it
indicates when a fault condition, such as excessive load-
ing, has pulled the output out of regulation.
Once the LTC1751-3.3/LTC1751-5 are enabled via the
SHDN pin, V
OUT
ramps to its final regulation value slowly
by following the SS pin. The PGOOD pin switches from low
impedance to high impedance after V
OUT
reaches its
regulation value. If V
OUT
is subsequently pulled below its
correct regulation level, the PGOOD pin pulls low again
indicating that a fault exists. Alternatively, if there is a short
circuit on V
OUT
preventing it from ever reaching its correct
regulation level, the PGOOD pin will remain low. The lower
fault threshold, UVL, is preprogrammed to recognize
errors of –7% below nominal V
OUT
. The upper fault
threshold, UVH, is preprogrammed at –4.5% below nomi-
nal. Figure 2 shows an example of the PGOOD pin with a
normal start-up followed by an undervoltage fault.
Using an external pull-up resistor, the PGOOD pin can be
pulled high from any available voltage supply, including
the LTC1751-3.3/LTC1751-5 V
OUT
pin.
If PGOOD is not used it may be connected to GND.
+
LTC1751-X
V
OUT
1
10
μ
F
TANT
+
10
μ
F
TANT
V
OUT
5V
1751 F01
Figure 1. Output Ripple Reduction Technique
SHDN
PGOOD
V
OUT
UVL
TIME
17515 F02
UVH
t
r
10%
90%
Figure 2. PGOOD During Start-Up and Undervoltage
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LTC1751 | Micropower, Regulated Charge Pump DC/DC Converters |
| LTC1751-3.3 | Micropower, Regulated Charge Pump DC/DC Converters |
| LTC1753 | 9-Bit D-Type Transparent Read-Back Latches With 3-State Outputs 24-PDIP 0 to 70 |
| LTC1753CG | Isolated Flyback Switching Regulator with 9V Output |
| LTC1753CSW | 10-Bit D-Type Transparent Read-Back Latches 24-SOIC 0 to 70 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LTC1751EMS8 | 功能描述:IC REG SWITCHD CAP DBL ADJ 8MSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- 類型:升壓（升壓） 輸出類型:可調(diào)式 輸出數(shù):1 輸出電壓:1.24 V ~ 30 V 輸入電壓:1.5 V ~ 12 V PWM 型:電流模式，混合 頻率 - 開關(guān):600kHz 電流 - 輸出:500mA 同步整流器:無 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:8-SOIC |
| LTC1751EMS8#PBF | 功能描述:IC REG SWITCHD CAP DBL ADJ 8MSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:250 系列:- 類型:降壓（降壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:1.2V 輸入電壓:2.05 V ~ 6 V PWM 型:電壓模式 頻率 - 開關(guān):2MHz 電流 - 輸出:500mA 同步整流器:是 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:6-UFDFN 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:6-SON（1.45x1） 產(chǎn)品目錄頁面:1032 (CN2011-ZH PDF) 其它名稱:296-25628-2 |
| LTC1751EMS8#TR | 功能描述:IC REG SWITCHD CAP DBL ADJ 8MSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- 類型:升壓（升壓） 輸出類型:可調(diào)式 輸出數(shù):1 輸出電壓:1.24 V ~ 30 V 輸入電壓:1.5 V ~ 12 V PWM 型:電流模式，混合 頻率 - 開關(guān):600kHz 電流 - 輸出:500mA 同步整流器:無 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:8-SOIC |
| LTC1751EMS8#TRPBF | 功能描述:IC REG SWITCHD CAP DBL ADJ 8MSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- 類型:升壓（升壓） 輸出類型:可調(diào)式 輸出數(shù):1 輸出電壓:1.24 V ~ 30 V 輸入電壓:1.5 V ~ 12 V PWM 型:電流模式，混合 頻率 - 開關(guān):600kHz 電流 - 輸出:500mA 同步整流器:無 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:8-SOIC |
| LTC1751EMS8-3.3 | 功能描述:IC REG SWITCHED CAP DBL 8MSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 產(chǎn)品培訓(xùn)模塊:MIC23xxx HyperLight Load™ Regulators 標(biāo)準(zhǔn)包裝:5,000 系列:HyperLight Load® 類型:降壓（降壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:1.8V 輸入電壓:2.7 V ~ 5.5 V PWM 型:混合物 頻率 - 開關(guān):4MHz 電流 - 輸出:2A 同步整流器:是 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:8-VFDFN 裸露焊盤，8-MLF? 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:8-MLF?（2x2） 產(chǎn)品目錄頁面:1094 (CN2011-ZH PDF) 其它名稱:576-3303-2 |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。