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参数资料
| 型号： | LTC3522EUD#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 10/20页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK BOOST SYNC ADJ 16QFN |
| 标准包装： | 2,500 |
| 类型： | 降压（降压），升压（升压） |
| 输出类型： | 可调式 |
| 输出数： | 2 |
| 输出电压： | 0.6 V ~ 5.5 V |
| 输入电压： | 2.4 V ~ 5.5 V |
| PWM 型： | 电流模式，混合 |
| 频率 - 开关： | 1.07MHz |
| 电流 - 输出： | 200mA，400mA |
| 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） |
LTC3522
OPERATION
Soft-Start
L
The buck converter has an internal voltage mode soft-start
PV IN1
A
SW1A
SW1B
D
V OUT1
circuit with a nominal duration of 600μs. The converter
remains in regulation during soft-start and will therefore
respond to output load transients which occur during
this time. In addition, the output voltage rise time has
B
C
minimal dependency on the size of the output capacitor
LTC3522
PGND1
PGND2
or load current.
Error Ampli?er and Compensation
The LT3522 buck converter utilizes an internal transcon-
ductance error ampli?er. Compensation of the feedback
loop is performed internally to reduce the size of the
application circuit and simplify the design process. The
compensation network has been designed to allow use of
a wide range of output capacitors while simultaneously
ensuring rapid response to load transients.
PGOOD2 Comparator
The PGOOD2 pin is an open-drain output which indicates
the status of the buck converter. If the buck output volt-
age falls 7.7% below the regulation voltage, the PGOOD2
open-drain output will pull low. The output voltage must
rise 2.5% above the falling threshold before the pull-down
will turn off. In addition, there is a 60μs typical deglitch-
ing delay in the ?ag in order to prevent false trips due
to voltage transients on load steps. The PGOOD2 output
will also pull low during overtemperature shutdown and
undervoltage lockout to indicate these fault conditions.
The PGOOD2 output is only active if the buck converter
is enabled.
BUCK-BOOST CONVERTER OPERATION
PWM Mode Operation
When the PWM pin is held high, the LTC3522 buck-boost
converter operates in a constant frequency PWM mode with
voltage mode control. A proprietary switching algorithm
allows the converter to switch between buck, buck-boost
and boost modes without discontinuity in inductor cur-
rent or loop characteristics. The switch topology for the
buck-boost converter is shown in Figure 1.
3522 F01
Figure 1. Buck-Boost Switch Topology
When the input voltage is signi?cantly greater than the
output voltage, the buck-boost converter operates in
buck mode. Switch D turns on continuously and switch
C remains off. Switches A and B are pulse width modu-
lated to produce the required duty cycle to support the
output regulation voltage. As the input voltage decreases,
switch A remains on for a larger portion of the switching
cycle. When the duty cycle reaches approximately 85%,
the switch pair AC begins turning on for a small fraction
of the switching period. As the input voltage decreases
further, the AC switch pair remains on for longer durations
and the duration of the BD phase decreases proportionally.
As the input voltage drops below the output voltage, the
AC phase will eventually increase to the point that there is
no longer any BD phase. At this point, switch A remains on
continuously while switch pair CD is pulse width modu-
lated to obtain the desired output voltage. At this point,
the converter is operating solely in boost mode.
This switching algorithm provides a seamless transition
between operating modes and eliminates discontinuities
in average inductor current, inductor current ripple, and
loop transfer function throughout all three operational
modes. These advantages result in increased ef?ciency
and stability in comparison to the traditional 4-switch
buck-boost converter.
Error Ampli?er and Compensation
The buck-boost converter utilizes a voltage mode error
ampli?er with an internal compensation network as shown
in Figure 2.
Notice that resistor R2 of the external resistor divider
network plays an integral role in determining the frequency
3522fa
10
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| LTC3523 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Synchronous 600mA Step-Up and 400mA Step-Down DC/DC Converters |
| LTC3523EUD#PBF | 功能描述:IC REG BUCK BOOST SYNC ADJ 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 |
| LTC3523EUD#TRPBF | 功能描述:IC REG BUCK BOOST SYNC ADJ 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 |
| LTC3523EUD-2#PBF | 功能描述:IC REG BUCK BOOST SYNC ADJ 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 |
| LTC3523EUD-2#TRPBF | 功能描述:IC REG BUCK BOOST SYNC ADJ 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 |
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