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参数资料
| 型号： | LTC3544BEUD#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 11/18页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK SYNC ADJ QUAD 16QFN |
| 标准包装： | 2,500 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 4 |
| 输出电压： | 0.8 V ~ 5.5 V |
| 输入电压： | 2.25 V ~ 5.5 V |
| PWM 型： | 电流模式 |
| 频率 - 开关： | 2.25MHz |
| 电流 - 输出： | 100mA，200mA（2），300mA |
| 同步整流器： | 是 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-WFQFN 裸露焊盘 |
| 包装： | 带卷 (TR) |
| 供应商设备封装： | 16-QFN-EP（3x3） |
LTC3544B
APPLICATIONS INFORMATION
Δ V OUT
? Δ I L ? ESR +
generally far exceeds the I RIPPLE(P-P) requirement. The
output ripple Δ V OUT is determined by:
? 1 ?
?
? 8? ? ? C OUT ?
LTC3544B
V FB
0.8V ≤ V OUT ≤ 5.5V
R2
R1
C F
V OUT = 0 . 8 V ? 1 +
wheref=operatingfrequency,C OUT =outputcapacitance
and Δ I L = ripple current in the inductor. For a fixed output
voltage, the output ripple is highest at maximum input
voltage since Δ I L increases with input voltage.
Using Ceramic Input and Output Capacitors
Higher value, lower cost, ceramic capacitors are now
widely available in smaller case sizes. Their high ripple
current, high voltage rating and low ESR make them
ideal for switching regulator applications. Because the
LTC3544B’s control loop does not depend on the output
capacitor’s ESR for stable operation, ceramic capacitors
can be used freely to achieve very low output ripple and
small circuit size.
However, care must be taken when ceramic capacitors are
used at the input and the output. When a ceramic capacitor
is used at the input and the power is supplied by a wall
adapter through long wires, a load step at the output can
induce ringing at the input, V IN . At best, this ringing can
couple to the output and be mistaken as loop instability. At
worst, a sudden inrush of current through the long wires
can potentially cause a voltage spike at V IN , large enough
to damage the part.
When choosing the input and output ceramic capacitors,
choose the X5R or X7R dielectric formulations. These
dielectrics have the best temperature and voltage charac-
teristics of all the ceramics for a given value and size.
Output Voltage Programming
The output voltage is set by tying V FB to a resistive divider
according to the following formula:
? R2 ?
?
? R 1 ?
The external resistive divider is connected to the output
allowing remote voltage sensing as shown in Figure 2.
GND
3544B F02
Figure 2. Setting the LTC3544B Output Voltage
Keeping the current in the resistors small maximizes the
efficiency, but making them too small may allow stray
capacitance to cause noise problems or reduce the phase
margin of the control loop. It is recommended that the
total feedback resistor string be kept to under 100k.
To improve the frequency response of the control loop, a
feed forward capacitor, C F , may be used. Great care should
be taken to route the feedback line away from noise sources
such as the inductor of the SW line.
Efficiency Considerations
The efficiency of a switching regulator is equal to the output
power divided by the input power times 100%. It is often
useful to analyze individual losses to determine what is
limiting the efficiency and which change would produce
the most improvement. Efficiency can be expressed as:
Efficiency = 100% – (L1 + L2 + L3 + ...) where L1, L2, etc.
are the individual losses as a percentage of input power.
Although all dissipative elements in the circuit produce
losses, two main sources usually account for most of the
losses in LTC3544B circuits: V IN quiescent current and I 2 R
losses. V IN quiescent current loss dominates the efficiency
loss at low load currents, whereas the I 2 R loss dominates
the efficiency loss at medium to high load currents.
1. The quiescent current is due to two components: the
DC bias current as given in the electrical characteristics
and the internal main switch and synchronous switch
gate charge currents. The gate charge current results
from switching the gate capacitance of the internal power
MOSFET switches. Each time the gate is switched from
high to low to high again, a packet of charge, dQ, moves
from PV IN to ground. The resulting dQ/dt is the current out
of PV IN that is typically larger than the DC bias current and
3544bfb
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3544EUD | 制造商:LINER 制造商全称:Linear Technology 功能描述:Quad Synchronous Step-Down Regulator: 2.25MHz, 300mA, 200mA, 200mA, 100mA |
| LTC3544EUD#PBF | 功能描述:IC REG BUCK SYNC ADJ QUAD 16QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:250 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V 输入电压:2.05 V ~ 6 V PWM 型:电压模式 频率 - 开关:2MHz 电流 - 输出:500mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:6-UFDFN 包装:带卷 (TR) 供应商设备封装:6-SON（1.45x1） 产品目录页面:1032 (CN2011-ZH PDF) 其它名称:296-25628-2 |
| LTC3544EUD#TRPBF | 功能描述:IC REG BUCK SYNC ADJ QUAD 16QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V，1.5V，1.8V，2.5V 输入电压:2.7 V ~ 20 V PWM 型:- 频率 - 开关:- 电流 - 输出:50mA 同步整流器:是 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 包装:带卷 (TR) 供应商设备封装:10-MSOP 裸露焊盘 |
| LTC3544EUDPBF | 制造商:Linear Technology 功能描述:2.25MHz Sync Step-Down Converter LTC3544 |
| LTC3544EUD-PBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Quad Synchronous Step-Down Regulator: 2.25MHz, 300mA, 200mA, 200mA, 100mA |
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