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參數(shù)資料
| 型號： | LTC3728LZEUH |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 3 A DUAL SWITCHING CONTROLLER, 590 kHz SWITCHING FREQ-MAX, PQCC28 |
| 封裝： | 5 X 5 MM, PLASTIC, MO-220WHHD, QFN-28 |
| 文件頁數(shù)： | 8/32頁 |
| 文件大?。?/td> | 467K |
| 代理商： | LTC3728LZEUH |
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LTC3728LZ
16
3728lzf
This formula has a maximum at VIN = 2VOUT, where IRMS
= IOUT/2. This simple worst case condition is commonly
used for design because even signicant deviations do not
offer much relief. Note that capacitor manufacturer’s ripple
current ratings are often based on only 2000 hours of life.
This makes it advisable to further derate the capacitor, or
to choose a capacitor rated at a higher temperature than
required. Several capacitors may also be paralleled to meet
size or height requirements in the design. Always consult
the manufacturer if there is any question.
The benet of the LTC3728LZ multiphase clocking can
be calculated by using the equation above for the higher
power controller and then calculating the loss that would
have resulted if both controller channels switched on at
the same time. The total RMS power lost is lower when
both controllers are operating due to the interleaving of
current pulses through the input capacitor’s ESR. This is
why the input capacitor’s requirement calculated above for
the worst-case controller is adequate for the dual controller
design. Remember that input protection fuse resistance,
battery resistance and PC board trace resistance losses are
also reduced due to the reduced peak currents in a multi-
phase system. The overall benet of a multiphase design
will only be fully realized when the source impedance of
the power supply/battery is included in the efciency test-
ing. The drains of the two top MOSFETs should be placed
within 1cm of each other and share a common CIN(s).
Separating the drains and CIN may produce undesirable
voltage and current resonances at VIN.
The selection of COUT is driven by the required effective
series resistance (ESR). Typically once the ESR require-
ment is satised the capacitance is adequate for ltering.
The output ripple (ΔVOUT) is determined by:
V
I ESR
fC
OUT
L
OUT
≈+
1
8
Where f = operating frequency, COUT = output capacitance,
and ΔIL= ripple current in the inductor. The output ripple
is highest at maximum input voltage since ΔIL increases
with input voltage. With ΔIL = 0.3IOUT(MAX) the output
ripple will typically be less than 50mV at the maximum
VIN assuming:
COUT Recommended ESR < 2 RSENSE
and COUT > 1/(8fRSENSE)
The rst condition relates to the ripple current into the ESR
of the output capacitance while the second term guarantees
that the output capacitance does not signicantly discharge
during the operating frequency period due to ripple current.
The choice of using smaller output capacitance increases
the ripple voltage due to the discharging term but can be
compensated for by using capacitors of very low ESR to
maintain the ripple voltage at or below 50mV. The ITH pin
OPTI-LOOP compensation components can be optimized
to provide stable, high performance transient response
regardless of the output capacitors selected.
Manufacturers such as Nichicon, United Chemi-Con and
Sanyo can be considered for high performance through-
hole capacitors. The OS-CON semiconductor dielectric
capacitor available from Sanyo has the lowest (ESR)(size)
product of any aluminum electrolytic at a somewhat
higher price. An additional ceramic capacitor in parallel
with OS-CON capacitors is recommended to reduce the
inductance effects.
In surface mount applications multiple capacitors may need
to be used in parallel to meet ESR, RMS current handling
and load step requirements. Aluminum electrolytic, dry
tantalum and special polymer capacitors are available in
surface mount packages. Special polymer surface mount
capacitors offer very low ESR but have lower storage ca-
pacity per unit volume than other capacitor types. These
capacitors offer a very cost-effective output capacitor
solution and are an ideal choice when combined with a
controller having high loop bandwidth. Tantalum capacitors
offer the highest capacitance density and are often used as
output capacitors for switching regulators having controlled
soft-start. Several excellent surge-tested choices are the
AVX TPS, AVX TPSV or the KEMET T510 series of surface
mount tantalums, available in case heights ranging from
2mm to 4mm. Aluminum electrolytic capacitors can be used
in cost-driven applications providing that consideration
is given to ripple current ratings, temperature and long
term reliability. A typical application will require several
to many aluminum electrolytic capacitors in parallel. A
combination of the above mentioned capacitors will often
result in maximizing performance and minimizing overall
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| LTC3728LZEUH#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 32-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 |
| LTC3728LZEUH#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 32-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 |
| LTC3729EG | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:否 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 |
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| LTC3729EG#PBF-ND | 制造商: 功能描述: 制造商:undefined 功能描述: |
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