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| 型号： | LTC1624CS8#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 9/28页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BST FLYBK INV 8SOIC |
| 标准包装： | 100 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 225kHz |
| 占空比： | 95% |
| 电源电压： | 3.5 V ~ 36 V |
| 降压： | 是 |
| 升压： | 是 |
| 回扫： | 是 |
| 反相： | 是 |
| 倍增器： | 无 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 无 |
| 工作温度： | 0°C ~ 70°C |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 包装： | 管件 |
| 产品目录页面： | 1333 (CN2011-ZH PDF) |
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LTC1624
APPLICATIO N S I N FOR M ATIO N
monly used for design because even significant 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 selection of C OUT is driven by the required effective
series resistance (ESR). Typically, once the ESR require-
ment is satisfied the capacitance is adequate for filtering.
The output ripple ( ? V OUT ) is determined by:
ratings that are ideal for input capacitor applications.
Consult the manufacturer for other specific recommend-
ations.
INTV CC Regulator
An internal regulator produces the 5V supply that powers
the drivers and internal circuitry within the LTC1624.
Good V IN bypassing is necessary to supply the high
transient currents required by the MOSFET gate drivers.
High input voltage applications in which large MOSFETs
are being driven at high frequencies may cause the maxi-
mum junction temperature rating for the LTC1624 to be
exceeded. The supply current is dominated by the gate
? V OUT L ? ESR +
≈ ? I
?
?
1 ?
4 fC OUT ? ?
charge supply current as discussed in the Efficiency
Considerations section. The junction temperature can be
estimated by using the equations given in Note 1 of the
where f = operating frequency, C OUT = output capacitance
and ? I L = ripple current in the inductor. The output ripple
is highest at maximum input voltage since ? I L increases
with input voltage. With ? I L = 0.4I OUT(MAX) the output
ripple will be less than 100mV at maximum V IN , assuming:
C OUT Required ESR < 2R SENSE
Manufacturers such as Nichicon, United Chemicon and
SANYO should 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 some-
what higher price. Once the ESR requirement for C OUT has
been met, the RMS current rating generally far exceeds
the I RIPPLE(P-P) requirement.
In surface mount applications multiple capacitors may
have to be paralleled to meet the ESR or RMS current
handling requirements of the application. Aluminum elec-
trolytic and dry tantalum capacitors are both available in
surface mount configurations. In the case of tantalum it is
critical that the capacitors are surge tested for use in
switching power supplies. An excellent choice is the AVX
TPS series of surface mount tantalums, available in case
heights ranging from 2mm to 4mm. Other capacitor types
include SANYO OS-CON, Nichicon WF series and Sprague
595D series and the new ceramics. Ceramic capacitors are
now available in extremely low ESR and high ripple current
Electrical Characteristics table. For example, the LTC1624
is limited to less than 17mA from a 30V supply:
T J = 70 ° C + (17mA)(30V)(110 ° C/W) = 126 ° C
To prevent maximum junction temperature from being
exceeded, the input supply current must be checked
operating in continuous mode at maximum V IN .
Step-Down Converter: Topside MOSFET Driver
Supply (C B , D B )
An external bootstrap capacitor C B connected to the BOOST
pin supplies the gate drive voltage for the topside MOSFET.
Capacitor C B in the functional diagram is charged through
internal diode D B from INTV CC when the SW pin is low.
When the topside MOSFET is to be turned on, the driver
places the C B voltage across the gate to source of the
MOSFET. This enhances the MOSFET and turns on the
topside switch. The switch node voltage SW rises to V IN
and the BOOST pin rises to V IN + INTV CC . The value of the
boost capacitor C B needs to be 50 times greater than the
total input capacitance of the topside MOSFET. In most
applications 0.1 μ F is adequate.
Significant efficiency gains can be realized by supplying
topside driver operating voltage from the output, since the
V IN current resulting from the driver and control currents
will be scaled by a factor of (Duty Cycle)/(Efficiency). For
5V regulators this simply means connecting the BOOST
9
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| LTC1624IS8 | 功能描述:IC REG CTRLR BST FLYBK INV 8SOIC RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
| LTC1624IS8#PBF | 功能描述:IC REG CTRLR BST FLYBK INV 8SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 特色产品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 标准包装:1 系列:PowerWise® PWM 型:电压模式 输出数:1 频率 - 最大:1MHz 占空比:81% 电源电压:4.5 V ~ 18 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-5°C ~ 125°C 封装/外壳:32-WFQFN 裸露焊盘 包装:Digi-Reel® 产品目录页面:1303 (CN2011-ZH PDF) 其它名称:LM3754SQDKR |
| LTC1624IS8#PBF | 制造商:Linear Technology 功能描述:DC/DC Converter IC |
| LTC1624IS8#TR | 功能描述:IC REG CTRLR BST FLYBK INV 8SOIC RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
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