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参数资料
| 型号： | LTC3542EDC-1#PBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | SWITCHING REGULATOR, 2700 kHz SWITCHING FREQ-MAX, PDSO6 |
| 封装： | 2 X 2 MM, LEAD FREE, PLASTIC, MO-229WCCD-2, DFN-6 |
| 文件页数： | 4/16页 |
| 文件大小： | 235K |
| 代理商： | LTC3542EDC-1#PBF |
LTC3542-1
12
35421f
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 LTC3542-1 does not dissipate
much heat due to its high efciency. But in applications
where the LTC3542-1 is running at high ambient tem-
perature 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 160°C, both power
switches will be turned off and the SW node will become
high impedance.
To avoid the LTC3542-1 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.
The junction temperature, TJ, is given by:
TJ = TA + TR
where TA is the ambient temperature.
As an example, consider the LTC3542-1 at an input voltage
of 3.6V, a load current of 500mA and an ambient tem-
perature of 70°C. From the typical performance graph of
switch resistance, the RDS(ON) of the P-channel switch at
70°C is approximately 0.6
Ω. Therefore, power dissipated
by the part is:
PD = ILOAD2 RDS(ON) = 150mW
For the DFN package, the
θJA is 89°C/W. Thus, the junction
temperature of the regulator is:
TJ = 70°C + 0.150 89 = 83.4°C
which is below the maximum junction temperature of
125°C.
Notethatathighersupplyvoltages,thejunctiontemperature
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 (>1μF) bypass capacitors.
The discharged bypass capacitors are effectively put in
APPLICATIONS INFORMATION
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PDF描述 |
|---|---|
| LTC3547BIDDB#TRM | 0.7 A DUAL SWITCHING CONTROLLER, 2700 kHz SWITCHING FREQ-MAX, PDSO8 |
| LTC3547BEDDB-1#PBF | 0.7 A DUAL SWITCHING CONTROLLER, 2700 kHz SWITCHING FREQ-MAX, PDSO8 |
| LTC3547BIDDB#PBF | 0.7 A DUAL SWITCHING CONTROLLER, 2700 kHz SWITCHING FREQ-MAX, PDSO8 |
| LTC3560ES6 | 2.1 A SWITCHING REGULATOR, 2700 kHz SWITCHING FREQ-MAX, PDSO6 |
| LTC3560ES6#TR | 2.1 A SWITCHING REGULATOR, 2700 kHz SWITCHING FREQ-MAX, PDSO6 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3542EDC-1-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:500mA, 2.25MHz 2.8V Output Synchronous Step-Down DC/DC Converter |
| LTC3542EDC-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 |
| LTC3542EDC-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:500mA, 2.25MHz Synchronous Step-Down DC/DC Converter |
| 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 |
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