参数资料
型号: LTC3251EMSE#TRPBF
厂商: Linear Technology
文件页数: 12/16页
文件大小: 0K
描述: IC REG BUCK SWITCHED CAP 10MSOP
标准包装: 2,500
类型: 降压(降压),切换电容(充电泵)
输出类型: 可调式
输出数: 1
输出电压: 0.9 V ~ 1.6 V
输入电压: 2.7 V ~ 5.5 V
PWM 型: 多重
频率 - 开关: 1MHz ~ 1.6MHz
电流 - 输出: 500mA
同步整流器:
工作温度: -40°C ~ 85°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
LTC3251/
LTC3251-1.2/LTC3251-1.5
OPERATIO
(Refer to Block Diagram)
temperature range, the 1 μ F, 10V, X5R or X7R will provide
more capacitance than the 4.7 μ F, 10V, Y5V. The capacitor
manufacturer’s data sheet should be consulted to deter-
mine what value of capacitor is needed to ensure mini-
mum capacitance values are met over operating tempera-
ture and bias voltage.
Below is a list of ceramic capacitor manufacturers and
how to contact them:
The flying capacitor pins C1 + , C1 – , C2 + , C2 – will have very
high edge rate wave forms. The large dv/dt on these pins
can couple energy capacitively to adjacent printed circuit
board runs. Magnetic fields can also be generated if the
flying capacitors are not close to the part (i.e., the loop area
is large). To decouple capacitive energy transfer, a Faraday
shield may be used. This is a grounded PC trace between
the sensitive node and the IC’s pins. For a high quality AC
ground, it should be returned to a solid ground plane that
AVX
Kemet
Murata
Taiyo Yuden
TDK
www.avxcorp.com
www.kemet.com
www.murata.com
www.t-yuden.com
www.tdk.com
extends all the way to the part. Keep the FB trace of the
LTC3251 away from or shielded from the flying capacitor
traces or degraded performance could result.
Thermal Management
Layout Considerations
Due to the high switching frequency and transient currents
produced by the LTC3251, careful board layout is neces-
sary for optimal performance. A true ground plane and
short connections to all capacitors will improve perfor-
mance and ensure proper regulation under all conditions.
Figure 6 shows the recommended layout configuration.
If the junction temperature increases above approximately
160 ° C, the thermal shutdown circuitry will automatically
deactivate the output. To reduce the maximum junction
temperature, a good thermal connection to the PC board
is recommended. Connecting the 10-pin MSE paddle
directly to a ground plane, and maintaining a solid ground
plane under the device on one or more layers of the PC
board, can reduce the thermal resistance of the package
and PC board considerably. Using this method a θ JA of
40 ° C/W should be achieved. The actual power dissipated
by the LTC3251 (PD) can be calculated by the following
PD = ? IN – V OUT ? I OUT
C I
1 μ F
LTC3251 COMPONENTS NOT USED ON
THE LTC3251-1.2 OR LTC3251-1.5
R B
equation:
? V ?
? 2 ?
V IN
C1
1 μ F
R A
C A
5pF
V OUT
Power Efficiency
GND
C O
10 μ F
C2
1 μ F
3251 F06
The power efficiency ( η ) of the LTC3251 family is approxi-
mately double that of a conventional linear regulator. This
occurs because the input current for a 2-to-1 step-down
charge pump is approximately half the output current. For
an ideal 2-to-1 step-down charge pump the power effi-
Figure 6. Recommended Layout
ciency is given by:
= =
η≡
P OUT
P IN
V OUT ? I OUT
1
V IN ? I OUT
2
2 V OUT
V IN
32511215fb
12
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LTC3252EDE#TR 功能描述:IC REG BUCK SWITCHED CAP 12DFN RoHS:否 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
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