- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄30771 > LTC3860IUH#PBF (LINEAR TECHNOLOGY CORP) DUAL SWITCHING CONTROLLER, 1250 kHz SWITCHING FREQ-MAX, PQCC32 PDF資料下載
參數(shù)資料
| 型號： | LTC3860IUH#PBF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | DUAL SWITCHING CONTROLLER, 1250 kHz SWITCHING FREQ-MAX, PQCC32 |
| 封裝： | 5 X 5 MM, LEAD FREE, PLASTIC, MO-220WHHD, QFN-32 |
| 文件頁數(shù)： | 19/36頁 |
| 文件大小： | 436K |
| 代理商： | LTC3860IUH#PBF |
第1頁第2頁第3頁第4頁第5頁第6頁第7頁第8頁第9頁第10頁第11頁第12頁第13頁第14頁第15頁第16頁第17頁第18頁當前第19頁第20頁第21頁第22頁第23頁第24頁第25頁第26頁第27頁第28頁第29頁第30頁第31頁第32頁第33頁第34頁第35頁第36頁
LTC3860
26
3860fc
APPLICATIONS INFORMATION
Efciency Considerations
The efciency of a switching regulator is equal to the
output power divided by the input power. It is often useful
to analyze individual losses to determine what is limiting
the efciency and which change would produce the most
improvement. Percent efciency can be expressed as:
%Efciency = 100% - (L1 + L2 + L3 + …)
where L1, L2, etc. are the individual losses as a percent-
age of input power.
Although all dissipative elements in the system produce
losses, three main sources usually account for most of the
losses in LTC3860 applications: 1) I2R losses, 2) topside
MOSFET transition losses, 3) gate drive current.
1. I2R losses occur mainly in the DC resistances of the
MOSFET, inductor, PCB routing, and input and output
capacitor ESR. Since each MOSFET is only on for part
of the cycle, its on-resistance is effectively multiplied
by the percentage of the cycle it is on. Therefore in high
step-down ratio applications the bottom MOSFET should
have a much lower RDS(ON) than the top MOSFET. It
is crucial that careful attention is paid to the layout of
the power path on the PCB to minimize its resistance.
In a 2-phase, 1.2V output, 60A system, 1mΩ of PCB
resistance at the output costs 5% in efciency.
2. Transition losses apply only to the topside MOSFET but
in 12V input applications are a very signicant source
of loss. They can be minimized by choosing a driver
with very low drive resistance and choosing a MOSFET
with low QG, RG and CRSS.
3. Gate drive current is equal to the sum of the top and
bottom MOSFET gate charges multiplied by the fre-
quency of operation. However, many drivers employ a
linear regulator to reduce the input voltage to a lower
gate drive voltage. This multiplies the gate loss by that
step down ratio. In high frequency applications it may
be worth using a secondary user supplied rail for gate
drive to avoid the linear regulator.
Other sources of loss include body or Schottky diode
conduction during the driver dependent non-overlap time
and inductor core losses.
Design Example
As a design example, consider a 2-phase application
where VIN = 12V, VOUT = 1.2V, ILOAD = 50A and fSWITCH =
600kHz. Assume that a secondary 5V supply is available
for the LTC3860 VCC supply.
The inductance value is chosen based on a 30% ripple
assumption. Each channel supplies an average 25A to the
load resulting in 7.5A peak-peak ripple:
ΔI
L =
V
OUT 1–
V
OUT
V
IN
f L
A 240nH inductor per phase will create 7.5A peak-to-peak
ripple. A 0.3μH inductor with a DCR of 0.7mΩ typical
is selected from the Vishay IHLP5050FD-01 series.
Connect CLKIN to SGND and FREQ to VCC to select
600kHz operation. Setting ILIMIT = 50A per phase leaves
plenty of headroom for transient conditions while still
adequately protecting against inductor saturation. This
corresponds to:
R
ILIM =
18.5 50A 0.7m
Ω+ 0.53V
20A
= 58.8kΩ
Choose 59.0kΩ.
For the DCR sense lter network, we can choose R = 2.0k
and C = 220nF to match the L/DCR time constant of the
inductor.
A loop crossover frequency of 100kHz provides good
transient performance while still being well below the
switching frequency of the converter. Four 330μF 9mΩ
POSCAPs are chosen for the output capacitors to maintain
supply regulation during severe transient conditions and
to minimize output voltage ripple.
The following compensation values (Figure 12) were
determined empirically:
R1 = 10k
R2 = 6.04k
R3 = 698
C1 = 680pF
C2 = 47pF
C3 = 390pF
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LTC3862HUH#TRPBF | DUAL SWITCHING CONTROLLER, 500 kHz SWITCHING FREQ-MAX, QCC24 |
| LTC3862IFE#PBF | DUAL SWITCHING CONTROLLER, 500 kHz SWITCHING FREQ-MAX, PDSO24 |
| LTC3862HFE#PBF | DUAL SWITCHING CONTROLLER, 500 kHz SWITCHING FREQ-MAX, PDSO24 |
| LTC3862EGN#TRPBF | DUAL SWITCHING CONTROLLER, 500 kHz SWITCHING FREQ-MAX, PDSO24 |
| LTC3862IUH#PBF | DUAL SWITCHING CONTROLLER, 500 kHz SWITCHING FREQ-MAX, QCC24 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LTC3861EUH-1#PBF | 制造商:Linear Technology 功能描述:IC REG CTRLR BUCK PWM VM 32-QFN 制造商:Linear Technology 功能描述:BUCK CNTRL DUAL 12PH 2.25MHZ 32QFN 制造商:Linear Technology 功能描述:BUCK, CNTRL, DUAL, 12PH, 2.25MHZ, 32QFN 制造商:Linear Technology 功能描述:PWM CONTROLLER, BUCK, 2.25MHZ, 24V, QFN-32, Input Voltage:24V, Output Voltage:5.5V, Output Current:60A, Supply Voltage Min:3V, Supply Voltage Max:5.5V, Digital IC Case Style:QFN, No. of Pins:32, Frequency:2.25MHz , RoHS Compliant: Yes 制造商:Linear Technology 功能描述:DP-SWREG/Controller, Dual-Phase/Dual-Channel Step-Down Voltage Mode Controller w |
| LTC3861EUH-1#TRPBF | 制造商:Linear Technology 功能描述:IC REG CTRLR BUCK PWM VM 32-QFN |
| LTC3861EUHE#PBF | 功能描述:IC REG CTRLR BUCK PWM VM 36-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® 標準包裝: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 |
| LTC3861EUHE#TRPBF | 功能描述:IC REG CTRLR BUCK PWM VM 36-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® 標準包裝:2,500 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:500kHz 占空比:96% 電源電壓:4 V ~ 36 V 降壓:無 升壓:是 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:24-WQFN 裸露焊盤 包裝:帶卷 (TR) |
| LTC3861IUH-1#PBF | 制造商:Linear Technology 功能描述:DC DC Cntrlr Dual-OUT Sync Step Down 3V to 24V Input 32-Pin QFN EP 制造商:Linear Technology 功能描述:IC REG CTRLR BUCK PWM VM 32-QFN 制造商:Linear Technology 功能描述:BUCK CNTRL DUAL 12PH 2.25MHZ 32QFN 制造商:Linear Technology 功能描述:BUCK, CNTRL, DUAL, 12PH, 2.25MHZ, 32QFN 制造商:Linear Technology 功能描述:DP-SWREG/Controller, Dual-Phase/Dual-Channel Step-Down Voltage Mode Controller w 制造商:Linear Technology 功能描述:PWM CONTROLLER, BUCK, 2.25MHZ, 24V, QFN-32, Input Voltage:24V, Output Voltage:5.5V, Output Current:60A, Supply Voltage Min:3V, Supply Voltage Max:5.5V, Digital IC Case Style:QFN, No. of Pins:32, Frequency:2.25MHz , RoHS Compliant: Yes |
發(fā)布緊急采購，3分鐘左右您將得到回復。