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参数资料
| 型号： | LTC3542ES6 |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | 0.5 A SWITCHING REGULATOR, 2700 kHz SWITCHING FREQ-MAX, PDSO6 |
| 封装： | PLASTIC, MO-193, TSOT-23, 6 PIN |
| 文件页数： | 3/16页 |
| 文件大小： | 263K |
| 代理商： | LTC3542ES6 |
LTC3542
11
3542f
3) The switching current is MOSFET gate charging current,
that results from switching the gate capacitance of the
power MOSFETs. Each time a MOSFET gate is switched
from low to high to low again, a packet of charge dQ moves
from VIN to ground. The resulting dQ/dt is a current out of
VIN that is typically much larger than the DC bias current.
In continuous mode, IGATECHG = fO(QT + QB), where QT
and QB are the gate charges of the internal top and bottom
MOSFET switches. The gate charge losses are proportional
to VIN and thus their effects will be more pronounced at
higher supply voltages.
Other “hidden” losses such as copper trace and internal
battery resistances can account for additional efciency
degradations in portable systems. The internal battery
and fuse resistance losses can be minimized by making
sure that CIN has adequate charge storage and very low
ESR at the switching frequency. Other losses include
diode conduction losses during dead-time and inductor
core losses generally account for less than 2% total ad-
ditional loss.
Thermal Considerations
In most applications the LTC3542 does not dissipate much
heat due to its high efciency. But in applications where the
LTC3542 is running at high ambient temperature with low
supply voltage and high duty cycles, such as in dropout,
the heat dissipated may exceed the maximum junction
temperature of the part. If the junction temperature reaches
approximately 150°C, both power switches will be turned
off and the SW node will become high impedance.
To avoid the LTC3542 from exceeding the maximum
junction temperature, the user need to do some thermal
analysis. The goal of the thermal analysis is to determine
whether the power dissipated exceeds the maximum
junction temperature of the part. The temperature rise is
given by:
TR = (PD)(θJA)
where PD is the power dissipated by the regulator and
θJA is the thermal resistance from the junction of the die
to the ambient.
APPLICATIO S I FOR ATIO
WU
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The junction temperature, TJ, is given by:
TJ = TA + TR
where TA is the ambient temperature.
As an example, consider the LTC3542 in dropout at an
input voltage of 2.7V, a load current of 500mA and an
ambient temperature of 70°C. From the typical performance
graph of switch resistance, the RDS(ON) of the P-channel
switch at 70°C is approximately 0.7
Ω. Therefore, power
dissipated by the part is:
PD = ILOAD
2 RDS(ON) = 175mW
For the DFN package, the
θJA is 40°C/W. Thus, the junction
temperature of the regulator is:
TJ = 70°C + 0.175 40 = 77°C
which is below the maximum junction temperature of
125°C.
Note that at higher supply voltages, the junction temperature
is lower due to reduced switch resistance (RDS(ON)).
Checking Transient Response
The regulator loop response can be checked by looking
at the load transient response. Switching regulators take
several cycles to respond to a step in load current. When
a load step occurs, VOUT immediately shifts by an amount
equal to
ΔILOAD ESR, where ESR is the effective series
resistance of COUT. ΔILOAD also begins to charge or dis-
charge COUT, generating a feedback error signal used by the
regulator to return VOUT to its steady-state value. During
this recovery time, VOUT can be monitored for overshoot
or ringing that would indicate a stability problem.
The output voltage settling behavior is related to the stability
of the closed-loop system and will demonstrate the actual
overall supply performance. For a detailed explanation of
optimizing the compensation components, including a re-
view of control loop theory, refer to Application Note 76.
In some applications, a more severe transient can be caused
by switching loads with large (>1F) bypass capacitors.
The discharged bypass capacitors are effectively put in
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相关代理商/技术参数 |
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|---|---|
| LTC3542ES6#PBF | 制造商:Linear Technology 功能描述:DC-DC CONVERTER BUCK 2.25MHZ 制造商:Linear Technology 功能描述:DC-DC CONVERTER, BUCK, 2.25MHZ, 500mA, TSOT-23-6; Primary Input Voltage:5.5V; No. of Outputs:1; Output Current:500mA; No. of Pins:6; Operating Temperature Min:-40C; Operating Temperature Max:85C; Package / Case:6-TSOT-23 ;RoHS Compliant: Yes |
| LTC3542ES6#TR | 制造商:Linear Technology 功能描述:Conv DC-DC Single Step Down 2.5V to 5.5V 6-Pin TSOT-23 T/R |
| LTC3542ES6#TRMPBF | 功能描述:IC REG BUCK SYNC ADJ TSOT23-6 RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 产品培训模块:High Efficiency Current Mode Switching Regulators CMOS LDO Regulators 特色产品:BD91x Series Step-Down Regulators 标准包装:2,500 系列:- 类型:降压（降压） 输出类型:两者兼有 输出数:2 输出电压:3.3V，0.8 V ~ 2.5 V 输入电压:4.5 V ~ 5.5 V PWM 型:电流模式 频率 - 开关:1MHz 电流 - 输出:1.5A 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:20-VFQFN 裸露焊盘 包装:带卷 (TR) 供应商设备封装:VQFN020V4040 产品目录页面:1373 (CN2011-ZH PDF) 其它名称:BD9152MUV-E2TR |
| LTC3542ES6#TRPBF | 功能描述:IC REG BUCK SYNC ADJ TSOT23-6 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:500 系列:- 类型:切换式电容器（充电泵），反相 输出类型:固定 输出数:1 输出电压:-3V 输入电压:2.3 V ~ 5.5 V PWM 型:Burst Mode? 频率 - 开关:900kHz 电流 - 输出:100mA 同步整流器:无 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-6 细型，TSOT-23-6 包装:带卷 (TR) 供应商设备封装:TSOT-23-6 其它名称:LTC1983ES6-3#TRMTR |
| LTC3542ES6-PBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:500mA, 2.25MHz Synchronous Step-Down DC/DC Converter |
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