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| 型号： | LTC1629IG-PG |
| 厂商： | Linear Technology |
| 文件页数： | 14/28页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 28-SSOP |
| 标准包装： | 47 |
| 系列： | PolyPhase® |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 360kHz |
| 占空比： | 99.5% |
| 电源电压： | 4 V ~ 36 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 ~ 85°C |
| 封装/外壳： | 28-SSOP（0.209"，5.30mm 宽） |
| 包装： | 管件 |
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LTC1629/LTC1629-PG
APPLICATIO S I FOR ATIO
? I
?
V
P MAIN = OUT ? MAX ? ( 1 + δ ) R DS ( ON ) +
k ( V IN ) ? MAX ? ( C RSS )( )
2 ? I ?
? N ?
? I
?
( )
P SYNC = IN OUT ? MAX ? 1 + δ R DS ( ON )
The MOSFET power dissipations at maximum output
current are given by:
2
V IN ? N ?
f
2
V – V
V IN ? N ?
where δ is the temperature dependency of R DS(ON) , k is a
constant inversely related to the gate drive current and N
is the number of stages.
Both MOSFETs have I 2 R losses but the topside N-channel
additional transition losses due to their larger junction
capacitance.
C IN and C OUT Selection
In continuous mode, the source current of each top
N-channel MOSFET is a square wave of duty cycle V OUT /
V IN . A low ESR input capacitor sized for the maximum
RMS current must be used. The details of a close form
equation can be found in Application Note 77. Figure 4
shows the input capacitor ripple current for different
phase configurations with the output voltage fixed and
input voltage varied. The input ripple current is normalized
against the DC output current. The graph can be used in
place of tedious calculations. The minimum input ripple
current can be achieved when the product of phase num-
ber and output voltage, N(V OUT ), is approximately equal to
the input voltage V IN or:
equation includes an additional term for transition losses,
which peak at the highest input voltage. For V IN < 20V the
high current efficiency generally improves with larger
V OUT
V IN
=
k
N
where k = 1, 2, …, N – 1
MOSFETs, while for V IN > 20V the transition losses rapidly
increase to the point that the use of a higher R DS(ON) device
with lower C RSS actual provides higher efficiency. The
synchronous MOSFET losses are greatest at high input
voltage when the top switch duty factor is low or during a
So the phase number can be chosen to minimize the input
capacitor size for the given input and output voltages.
In the graph of Figure 4, the local maximum input RMS
capacitor currents are reached when:
short-circuit when the synchronous switch is on close to
100% of the period.
The term (1 + δ ) is generally given for a MOSFET in the
V OUT
V IN
=
2 k ? 1
2 N
where k = 1, 2, …, N
form of a normalized R DS(ON) vs. Temperature curve, but
δ = 0.005/ ° C can be used as an approximation for low
voltage MOSFETs. C RSS is usually specified in the MOS-
FET characteristics. The constant k = 1.7 can be used to
0.6
0.5
estimate the contributions of the two terms in the main
switch dissipation equation.
The Schottky diodes, D1 and D2 shown in Figure 1 conduct
during the dead-time between the conduction of the two
large power MOSFETs. This helps prevent the body diode
of the bottom MOSFET from turning on, storing charge
0.4
0.3
0.2
0.1
1-PHASE
2-PHASE
3-PHASE
4-PHASE
6-PHASE
during the dead-time, and requiring a reverse recovery
period which would reduce efficiency. A 1A to 3A (depend-
ing on output current) Schottky diode is generally a good
0
0.1
0.2
0.3 0.4 0.5 0.6 0.7
DUTY FACTOR (V OUT /V IN )
0.8 0.9
1629 F04
compromise for both regions of operation due to the
relatively small average current. Larger diodes result in
14
Figure 4. Normalized Input RMS Ripple Current vs
Duty Factor for 1 to 6 Output Stages
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| LTC1629IG-PG#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 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 |
| LTC1629IG-PG#TR | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 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 |
| LTC1629IG-PG#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 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 |
| LTC1642ACGN | 制造商:Linear Technology 功能描述:Hot Swap Controller 1-CH 16.5V 16-Pin SSOP N |
| LTC1642ACGN#PBF | 功能描述:IC CONTROLLER HOTSWAP ADJ 16SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 热交换 系列:- 产品培训模块:Obsolescence Mitigation Program 标准包装:100 系列:- 类型:热插拔开关 应用:通用 内部开关:是 电流限制:可调 电源电压:9 V ~ 13.2 V 工作温度:-40°C ~ 150°C 安装类型:表面贴装 封装/外壳:10-WFDFN 裸露焊盘 供应商设备封装:10-TDFN-EP（3x3） 包装:管件 |
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