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参数资料
| 型号： | LTC3538EDCB#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 9/16页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK BOOST SYNC ADJ 8DFN |
| 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： | 1 |
| 输出电压： | 1.8 V ~ 5.25 V |
| 输入电压： | 2.4 V ~ 5.5 V |
| 频率 - 开关： | 1MHz |
| 电流 - 输出： | 800mA |
| 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： | 8-WFDFN 裸露焊盘 |
| 包装： | 带卷 (TR) |
| 供应商设备封装： | 8-DFN（3x2） |
LTC3538
OPERATION
Depending on the V C voltage, the LTC3538 will operate in
either buck, buck-boost or boost mode. The four power
switches are properly phased so the transfer between
operating modes is continuous, smooth and transparent to
the user. When V IN approaches V OUT the buck-boost region
is entered, where the conduction time of the four-switch
region is typically 150ns. Referring to Figures 1 and 2, the
various regions of operation will now be described.
88%
Buck-Boost or Four Switch (V IN ~ V OUT )
When the control voltage, V C , is above voltage V2, switch
pair AD remains on for duty cycle D MAX_BUCK , and the switch
pair AC begins to phase in. As switch pair AC phases in,
switch pair BD phases out accordingly. When V C reaches
the edge of the buck-boost range, at voltage V3, the AC
switch pair completely phase out the BD pair, and the boost
phase begins at duty cycle D4 SW . The input voltage, V IN ,
where the four switch region begins is given by:
D MAX
BOOST
A ON, B OFF
PWM C, D SWITCHES
BOOST REGION
V4 (~2.2V)
V IN = V OUT (1 – D4 SW ) ≈ 0.85 ? V OUT
The point at which the four-switch region ends is given
D MIN
BOOST
D MAX
BUCK
FOUR-SWITCH PWM
D ON, C OFF
PWM A, B SWITCHES
BUCK-BOOST
REGION
BUCK REGION
V3 (~1.8V)
V2 (~1.7V)
by:
V IN =
V OUT
1 ? D4 SW
V ≈ 1.18 ? V OUT
0%
V1 (~1.2V)
DUTY
CYCLE
3538 F02
CONTROL
VOLTAGE, V C
Boost Region (V IN < V OUT )
Switch A is always on and switch B is always off during
Figure 2. Switch Control vs Control Voltage, V C
Buck Region (V IN > V OUT )
Switch D is always on and switch C is always off during
this mode. When the control voltage, V C , is above volt-
age V1, output A begins to switch. During the off time of
switch A, synchronous switch B turns on for the remainder
of the period. Switches A and B will alternate similar to a
typical synchronous buck regulator. As the control volt-
age increases, the duty cycle of switch A increases until
the maximum duty cycle of the converter in buck mode
reaches D MAX_BUCK , given by:
D MAX_BUCK = 100 – D4 SW %
where D4 SW = duty cycle % of the four switch range.
D4 SW = (150ns ? f) ? 100 %
where f = operating frequency, Hz.
Beyond this point the four switch, or buck-boost region
is reached.
this mode. When the control voltage, V C , is above volt-
age V3, switch pair CD will alternately switch to provide
a boosted output voltage. This operation is typical to a
synchronous boost regulator. The maximum duty cycle
of the converter is limited to 88% typical and is reached
when V C is above V4.
Burst Mode OPERATION
Burst Mode operation reduces quiescent current consump-
tion of the LTC3538 at light loads and improves overall
conversion ef?ciency, increasing battery life. During Burst
Mode operation the LTC3538 delivers energy to the out-
put until it is regulated and then goes into a sleep mode
where the outputs are off and the quiescent current drops
to 35μA. In this mode the output ripple has a variable
frequency component that depends upon load current,
and will typically be about 2% peak-to-peak. Burst Mode
operation ripple can be reduced slightly by using more
output capacitance. Another method of reducing Burst
Mode operation ripple is to place a small feed-forward
capacitor across the upper resistor in the V OUT feedback
divider network (as in Type III compensation).
3538fb
9
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3539 | 制造商:LINER 制造商全称:Linear Technology 功能描述:400mA Step-Up DC/DC Converter with Maximum Power Point Control and 250mV Start-Up |
| LTC3539-2 | 制造商:LINER 制造商全称:Linear Technology 功能描述:400mA Step-Up DC/DC Converter with Maximum Power Point Control and 250mV Start-Up |
| LTC3539EDCB#PBF | 制造商:Linear Technology 功能描述: 制造商:Linear Technology 功能描述:DP-SWREG/Monolithic, Cut Tape 2A, 1MHz Synchronous Step-Up DC/DC Converter in 2m |
| LTC3539EDCB#TRMPBF | 功能描述:IC REG BOOST SYNC ADJ 2A 8DFN 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 |
| LTC3539EDCB#TRPBF | 功能描述:IC REG BOOST SYNC ADJ 2A 8DFN 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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