- 您现在的位置：买卖IC网 > PDF目录1830 > LTC3564IS5#TRPBF (Linear Technology)IC REG BUCK SYNC ADJ TSOT23-5 PDF资料下载
参数资料
| 型号： | LTC3564IS5#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 12/20页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK SYNC ADJ TSOT23-5 |
| 标准包装： | 2,500 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 0.6 V ~ 5.5 V |
| 输入电压： | 2.5 V ~ 5.5 V |
| PWM 型： | 电流模式，混合 |
| 频率 - 开关： | 2.25MHz |
| 电流 - 输出： | 1.25A |
| 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： | SOT-23-5 细型，TSOT-23-5 |
| 包装： | 带卷 (TR) |
| 供应商设备封装： | TSOT-23-5 |
LTC3564
APPLICATIO S I FOR ATIO
The R DS(ON) for both the top and bottom MOSFETs can
be obtained from the Typical Performance Characteris-
tics curves. Thus, to obtain I 2 R losses, simply add R SW
to R L and multiply the result by the square of the
average output current.
Other losses including C IN and C OUT ESR dissipative
losses and inductor core losses which generally account
for less than 2% total additional loss.
Thermal Considerations
In most applications the LTC3564 does not dissipate
much heat due to its high efficiency. But, in applications
where the LTC3564 is running at high ambient tempera-
ture with low supply voltage and high duty cycles, such
as in dropout, the heat dissipated may exceed the maxi-
mum 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 LTC3564 from exceeding the maximum
junction temperature, the user will 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 tempera-
ture rise is given by:
T R = (P D )( θ JA )
where P D is the power dissipated by the regulator and θ JA
is the thermal resistance from the junction of the die to the
ambient temperature.
The junction temperature, T J , is given by:
T J = T A + T R
where T A is the ambient temperature.
As an example, consider the LTC3564 in dropout at an
input voltage of 2.7V, a load current of 1.2A and an
ambient temperature of 70 ° C. From the typical perfor-
mance graph of switch resistance, the R DS(ON) of the
P-channel switch at 70 ° C is approximately ~0.2 Ω . There-
fore, power dissipated by the part is:
P D = I LOAD2 ? R DS(ON) = 288mW
For the SOT-23 package, the θ JA is 215 ° C/ W. Thus, the
junction temperature of the regulator is:
T J = 70 ° C + (0.288)(215) = 131.9 ° C
which is above the maximum junction temperature of
125 ° C.
Note that at higher supply voltages, the junction tempera-
ture is lower due to reduced switch resistance (R DS(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, V OUT immediately shifts by an amount
equal to ( Δ I LOAD ? ESR), where ESR is the effective series
resistance of C OUT . Δ I LOAD also begins to charge or
discharge C OUT , which generates a feedback error signal.
The regulator loop then acts to return V OUT to its steady-
state value. During this recovery time V OUT can be moni-
tored for overshoot or ringing that would indicate a stability
problem. For a detailed explanation of switching control
loop theory, see Application Note 76.
A second, more severe transient is caused by switching in
loads with large (>1 μ F) supply bypass capacitors. The
discharged bypass capacitors are effectively put in parallel
with C OUT , causing a rapid drop in V OUT . No regulator can
deliver enough current to prevent this problem if the load
switch resistance is low and it is driven quickly. The only
solution is to limit the rise time of the switch drive so that
the load rise time is limited to approximately (25 ? C LOAD ).
Thus, a 10 μ F capacitor charging to 3.3V would require a
250 μ s rise time, limiting the charging current to about
130mA.
3564f
12
相关PDF资料 |
PDF描述 |
|---|---|
| LTC3565IMSE#TRPBF | IC REG BUCK SYNC ADJ 10MSOP |
| LTC3568IDD#TRPBF | IC REG BUCK SYNC ADJ 1.8A 10DFN |
| LTC3569IFE#TRPBF | IC REG BUCK SYNC ADJ 16TSSOP |
| LTC3600EMSE#PBF | IC REG BUCK SYNC ADJ 1.5A 12MSOP |
| LTC3601IUD#TRPBF | IC REG BUCK SYNC ADJ 1.5A 16QFN |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3565 | 制造商:LINER 制造商全称:Linear Technology 功能描述:1.25A, 4MHz, Synchronous Step-Down DC/DC Converter |
| LTC3565_1 | 制造商:LINER 制造商全称:Linear Technology 功能描述:1.25A, 4MHz, Synchronous Step-Down DC/DC Converter |
| LTC3565_12 | 制造商:LINER 制造商全称:Linear Technology 功能描述:1.25A, 4MHz, Synchronous Step-Down DC/DC Converter |
| LTC3565EDD | 制造商:LINER 制造商全称:Linear Technology 功能描述:1.25A, 4MHz, Synchronous Step-Down DC/DC Converter |
| LTC3565EDD#PBF | 功能描述:IC REG BUCK SYNC ADJ 1.25A 10DFN 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 |
发布紧急采购，3分钟左右您将得到回复。