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參數(shù)資料
| 型號： | LTC3546EFE |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | DUAL SWITCHING CONTROLLER, 4000 kHz SWITCHING FREQ-MAX, PDSO28 |
| 封裝： | 4.40 MM, PLASTIC, TSSOP-28 |
| 文件頁數(shù)： | 11/28頁 |
| 文件大小： | 356K |
| 代理商： | LTC3546EFE |
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LTC3546
19
3546fb
APPLICATIONS INFORMATION
The LTC3546 can also track an external voltage during
startup by using an external voltage divider to the TRACK/SS
pin, and also insuring that the ramp rate on the TRACK/SS
pin is slower than the internal 1.2ms ramp rate.
As indicated in Figure 3, a resistor divider from an external
voltage can be connected to the TRACK/SS pin to allow
the start-up of VOUT to ratiometrically track an external
voltage VX.
For VTRACKSS < 0.6V
VV
RX
RX R X
RR
R
OUT
X
=
+
+
2
12
2
Table 2 summarizes the different states in which the
TRACK/SS can be used.
Table 2. The States of the TRACK/SS Pin
TRACK/SS PIN
RESULT
Capacitor to Ground
External Soft-Start
Floating
Internal Soft-Start
Resistor Divider
VOUT Tracking an External Voltage VX
Regardless of the mode implemented, the TRACK/SS pin
should never be pulled high externally as this will result
in excessive current during shutdown.
The LTC3546 can smoothly handle starting up into a pre-
biased output. The tracking function will pick up from the
pre-biased voltage and ramp the output up from there.
Mode Selection
The SYNC/MODE pin is a multipurpose pin which provides
mode selection and frequency synchronization. Connecting
this pin to VINenablesBurstModeoperationforbothregula-
Figure 3. Tracking External Voltages
Figure 4. Coincident Tracking
3546 F03
LTC3546
VTRACK/SS
R1
VFB
R2
VX
VOUT
R1X
R2X
3546 F04
TIME
OUTPUT
VOL
TAGE
VX
VOUT
Figure 5. Ratiometric Tracking
3546 F05
TIME
OUTPUT
VOL
TAGE
VX
VOUT
Coincident tracking is where VOUT = VX during startup. To
implement coincident tracking R1X in Figure 3 is set to the
same value as R1 and R2X to the value of R2. Coincident
tracking is illustrated in Figure 4. The voltage at TRACK/SS
when VX is at its nal value should be ≥0.8V (sufcient
margin above the 0.6V reference voltage).
Ratiometric tracking is where VOUT ≠ VX during startup
but rather, it is set to some fractional value of VX. To
implement ratiometric tracking (as illustrated in Figure
5), set R1X in Figure 3 to the same value as R1 and R2X
to the value of R2 + ΔR. The ΔR added to R2 should be
sufcient so that the TRACK/SS voltage is ≥ 0.8V when
VX is at its nal value.
The internal 1.15μA pull up current on TRACK/SS can cause
a tracking error at VOUT when using a resistor divider on
TRACK/SS. For example, if a 59k resistor is chosen for
R2X, the R2X current will be about 10μA (0.6V/59k). In this
case, the 1.15μA internal current source will cause about
11% (1.15μA/10μA) tracking error, which is about 66mV
referred to VFB. This is acceptable for most applications.
If a better tracking accuracy is required, the value of R2X
can be reduced or the 1.15μA current can be taken into
account in the equations.
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| LTC3546EFE#PBF | 功能描述:IC REG BUCK SYNC ADJ DL 28TSSOP 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:- 標準包裝: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 |
| LTC3546EFE#PBF | 制造商:Linear Technology 功能描述:IC DUAL SYNC STEP-DOWN DC/DC REG 28-TSSO |
| LTC3546EFE#TRPBF | 功能描述:IC REG BUCK SYNC ADJ DL 28TSSOP 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:- 設(shè)計資源:Design Support Tool 標準包裝:1 系列:- 類型:升壓（升壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:3V 輸入電壓:0.75 V ~ 2 V PWM 型:- 頻率 - 開關(guān):- 電流 - 輸出:100mA 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:SOT-23-5 細型，TSOT-23-5 包裝:剪切帶 (CT) 供應(yīng)商設(shè)備封裝:TSOT-23-5 其它名稱:AS1323-BTTT-30CT |
| LTC3546EFEPBF | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Dual Synchronous, 3A/1A or 2A/2A Confi gurable Step-Down DC/DC Regulator |
| LTC3546EFETRPBF | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Dual Synchronous, 3A/1A or 2A/2A Confi gurable Step-Down DC/DC Regulator |
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