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參數(shù)資料
| 型號： | LTC3879IUD#PBF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | SWITCHING CONTROLLER, PQCC16 |
| 封裝： | 3 X 3 MM, LEAD FREE, PLASTIC, MO-220WEED-4, QFN-16 |
| 文件頁數(shù)： | 9/28頁 |
| 文件大?。?/td> | 302K |
| 代理商： | LTC3879IUD#PBF |
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LTC3879
17
3879f
APPLICATIONS INFORMATION
The LTC3879 is designed to start up into pre-biased outputs
with no reverse current. Both TG and BG outputs remain
low until the applied TRACK/SS voltage plus internal offset
exceeds the voltage on the VFB pin. Once this condition
is exceeded, the switcher will start up normally and track
the TRACK/SS voltage until it exceeds 0.6V. Once switch-
ing starts, the mode of operation is determined by the
externally programmed MODE pin input. When TRACK/SS
exceeds 0.6V, the output regulates to the internal reference
value of 0.6V.
When the regulator is congured to track another supply,
the feedback voltage of the other supply is duplicated
by a resistor divider and applied to the TRACK/SS pin.
Therefore, the voltage ramp rate on this pin is determined
by the ramp rate of the other supply’s voltage. Note that
the small soft-start capacitor charging current is always
owing, producing a small offset error. To minimize this
error, one can select the tracking resistive divider value to
be small enough to make this error negligible.
In order to track down another supply after the soft-start
phase expires, the LTC3879 must be congured for forced
continuous operation.
Output Voltage Tracking
The LTC3879 allows the user to program how its output
ramps up and down by means of the TRACK/SS pin.
Through this pin, the output can be set up to either co-
incidentally or ratiometrically track with another supply’s
output, as shown in Figure 7. In the following discussions,
VMASTER refers to a master supply and VOUT refers to the
LTC3879’s output as a slave supply. To implement the
coincident tracking in Figure 7, connect a resistor divider
to the VMASTER, and connect its midpoint to the TRACK/SS
pin of the LTC3879. The track divider should be the same
as the LTC3879’s feedback divider. In this tracking mode,
VOUT_MASTER must be higher than VOUT. To implement
ratiometric tracking, the ratio of the resistor divider con-
nected to VOUT_MASTER is determined by:
V
RR
R
OUT MASTER
=
+
06
34
4
.
TIME
VMASTER
VOUT
OUTPUT
VOLTAGE
3879 F07a
(7a) Coincident Tracking
TIME
VMASTER
VOUT
OUTPUT
VOLTAGE
3879 F07b
(7b) Ratiometric Tracking
TO
TRACK/SS
PIN
VOUT_MASTER
R1
R2
3879 F08a
TO
VFB
PIN
VOUT
R1
R2
Figure 7. Two Different Modes of Output Voltage Tracking
(8a) Coincident Tracking Setup
TO
TRACK/SS
PIN
VOUT_MASTER
R3
R4
3879 F08b
TO
VFB
PIN
VOUT
R1
R2
(8b) Ratiometric Tracking Setup
Figure 8. Setup for Coincident and Ratiometric Tracking
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LTC3880EUJ#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 40-QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:PolyPhase® 特色產(chǎn)品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 標(biāo)準(zhǔn)包裝:1 系列:PowerWise® PWM 型:電壓模式 輸出數(shù):1 頻率 - 最大:1MHz 占空比:81% 電源電壓:4.5 V ~ 18 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-5°C ~ 125°C 封裝/外殼:32-WFQFN 裸露焊盤 包裝:Digi-Reel® 產(chǎn)品目錄頁面:1303 (CN2011-ZH PDF) 其它名稱:LM3754SQDKR |
| LTC3880EUJ#TRMPBF | 功能描述:IC REG CTRLR BUCK PWM CM 40-QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:PolyPhase® 標(biāo)準(zhǔn)包裝:4,000 系列:- PWM 型:電壓模式 輸出數(shù):1 頻率 - 最大:1.5MHz 占空比:66.7% 電源電壓:4.75 V ~ 5.25 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 85°C 封裝/外殼:40-VFQFN 裸露焊盤 包裝:帶卷 (TR) |
| LTC3880EUJ#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 40-QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:PolyPhase® 標(biāo)準(zhǔn)包裝:4,500 系列:PowerWise® PWM 型:控制器 輸出數(shù):1 頻率 - 最大:1MHz 占空比:95% 電源電壓:2.8 V ~ 5.5 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 125°C 封裝/外殼:6-WDFN 裸露焊盤 包裝:帶卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名稱:LM1771SSDX |
| LTC3880EUJ-1#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 40-QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:PolyPhase® 特色產(chǎn)品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 標(biāo)準(zhǔn)包裝:1 系列:PowerWise® PWM 型:電壓模式 輸出數(shù):1 頻率 - 最大:1MHz 占空比:81% 電源電壓:4.5 V ~ 18 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-5°C ~ 125°C 封裝/外殼:32-WFQFN 裸露焊盤 包裝:Digi-Reel® 產(chǎn)品目錄頁面:1303 (CN2011-ZH PDF) 其它名稱:LM3754SQDKR |
| LTC3880EUJ-1#TRMPBF | 功能描述:IC REG CTRLR BUCK PWM CM 40-QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:PolyPhase® 標(biāo)準(zhǔn)包裝:4,000 系列:- PWM 型:電壓模式 輸出數(shù):1 頻率 - 最大:1.5MHz 占空比:66.7% 電源電壓:4.75 V ~ 5.25 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 85°C 封裝/外殼:40-VFQFN 裸露焊盤 包裝:帶卷 (TR) |
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