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參數資料
| 型號： | LTC3859EFE#TRPBF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | SWITCHING CONTROLLER, 900 kHz SWITCHING FREQ-MAX, PDSO38 |
| 封裝： | 4.40 MM, LEAD FREE, PLASTIC, TSSOP-38 |
| 文件頁數： | 19/42頁 |
| 文件大小： | 624K |
| 代理商： | LTC3859EFE#TRPBF |
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LTC3859
26
3859fa
APPLICATIONS INFORMATION
Alternatively, the TRACK/SS1 and TRACK/SS2 pins for the
two buck controllers can be used to track two (or more) sup-
plies during start-up, as shown qualitatively in Figures 7a
and 7b. To do this, a resistor divider should be connected
from the master supply (VX) to the TRACK/SS pin of the
slave supply (VOUT), as shown in Figure 8. During start-up
VOUT will track VX according to the ratio set by the resis-
tor divider:
V
X
V
OUT
=
R
A
R
TRACKA
R
TRACKA + RTRACKB
R
A + RB
For coincident tracking (VOUT = VX during start-up),
RA = RTRACKA
RB = RTRACKB
INTVCC Regulators
The LTC3859 features two separate internal P-channel
low dropout linear regulators (LDO) that supply power
at the INTVCC pin from either the VBIAS supply pin or the
EXTVCC pin depending on the connection of the EXTVCC
pin. INTVCC powers the gate drivers and much of the
LTC3859’s internal circuitry. The VBIAS LDO and the EXTVCC
LDO regulate INTVCC to 5.4V. Each of these can supply a
peak current of 50mA and must be bypassed to ground
with a minimum of 4.7μF ceramic capacitor. No matter
what type of bulk capacitor is used, an additional 1μF
ceramic capacitor placed directly adjacent to the INTVCC
and PGND IC pins is highly recommended. Good bypassing
is needed to supply the high transient currents required
by the MOSFET gate drivers and to prevent interaction
between the channels.
High input voltage applications in which large MOSFETs
are being driven at high frequencies may cause the
maximum junction temperature rating for the LTC3859 to
be exceeded. The INTVCC current, which is dominated by
the gate charge current, may be supplied by either the VBIAS
LDO or the EXTVCC LDO. When the voltage on the EXTVCC
pin is less than 4.7V, the VBIAS LDO is enabled. Power
dissipation for the IC in this case is highest and is equal to
VBIAS IINTVCC. The gate charge current is dependent
on operating frequency as discussed in the Efciency
Considerations section. The junction temperature can be
estimated by using the equations given in Note 2 of the
Electrical Characteristics. For example, the LTC3859 INTVCC
current is limited to less than 40mA from a 40V supply
when not using the EXTVCC supply at a 70°C ambient
temperature in the QFN package:
TJ = 70°C + (40mA)(40V)(34°C/W) = 125°C
7a. Coincident Tracking
7b. Radiometric Tracking
Figure 7. Two Different Modes of Output Voltage Tracking
Figure 8. Using the TRACK/SS Pin for Tracking
3859 F07a
VX(MASTER)
VOUT(SLAVE)
OUTPUT
(V
OUT
)
TIME
3859 F07b
VX(MASTER)
VOUT(SLAVE)
OUTPUT
(V
OUT
)
TIME
3859 F08
LTC3859
VFB1,2
TRACK/SS1,2
RB
RA
VOUT
RTRACKB
RTRACKA
VX
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相關代理商/技術參數 |
參數描述 |
|---|---|
| LTC3859EUHF#PBF | 功能描述:IC REG CTRLR BST PWM CM 38-QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 特色產品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 標準包裝:1 系列:PowerWise® PWM 型:電壓模式 輸出數: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® 產品目錄頁面:1303 (CN2011-ZH PDF) 其它名稱:LM3754SQDKR |
| LTC3859EUHF#TRPBF | 功能描述:IC REG CTRLR BST PWM CM 38-QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標準包裝:4,500 系列:PowerWise® PWM 型:控制器 輸出數: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 |
| LTC3859IFE#PBF | 功能描述:IC REG CTRLR BST PWM CM 38-TSSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標準包裝:4,500 系列:PowerWise® PWM 型:控制器 輸出數: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 |
| LTC3859IFE#TRPBF | 功能描述:IC REG CTRLR BST PWM CM 38-TSSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標準包裝:4,500 系列:PowerWise® PWM 型:控制器 輸出數: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 |
| LTC3859IUHF#PBF | 功能描述:IC REG CTRLR BST PWM CM 38VQFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標準包裝:2,000 系列:- PWM 型:電流模式 輸出數:1 頻率 - 最大:1MHz 占空比:50% 電源電壓:9 V ~ 10 V 降壓:無 升壓:是 回掃:是 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:8-TSSOP（0.173"，4.40mm 寬） 包裝:帶卷 (TR) |
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