- 您现在的位置：买卖IC网 > PDF目录69007 > LTC4269CDKD-2#TR (LINEAR TECHNOLOGY CORP) SWITCHING CONTROLLER, 560 kHz SWITCHING FREQ-MAX, PDSO32 PDF资料下载
参数资料
| 型号： | LTC4269CDKD-2#TR |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | SWITCHING CONTROLLER, 560 kHz SWITCHING FREQ-MAX, PDSO32 |
| 封装： | 7 X 4 MM, PLASTIC, M0-229, DFN-32 |
| 文件页数： | 22/34页 |
| 文件大小： | 383K |
| 代理商： | LTC4269CDKD-2#TR |
第1页第2页第3页第4页第5页第6页第7页第8页第9页第10页第11页第12页第13页第14页第15页第16页第17页第18页第19页第20页第21页当前第22页第23页第24页第25页第26页第27页第28页第29页第30页第31页第32页第33页第34页
LTC4269-2
42692fb
applicaTions inForMaTion
tCHARGE is calculated by assuming the following:
VREF = 2.5V, RT = 35.7k, RB = 100k, CSS = 0.1F and
VSS(MIN) = 0.45V.
tCHARGE = t(VSS = 0.8V) – t(VSS = 0.45V)
Step 1:
SS_MAXDC(DC) = 2.5[100k/(35.7k + 100k)] = 1.84V
RCHARGE = (35.7k 100k/135.7k) = 26.3k
Step 2:
t(VSS = 0.45V) is calculated from:
t = RCHARGE CSS (–1) ln(1 – VSS/SS_MAXDC(DC))
= 2.63e4 1e–7 (–1) ln(1 – 0.45/1.84)
= 2.63e–3 (–1) ln(0.755) = 7.3e–4 s
Step 3:
t(VSS = 0.8V) is calculated from:
t = RCHARGE CSS (–1) ln(1 – VSS/SS–MAXDC(DC))
= 2.63e4 1e–7 (–1) ln(1 – 0.8/1.84)
= 2.63e–3 (–1) ln(0.565) = 1.5e–3 s
From Step 1 and Step 2
tCHARGE = (1.5 – 0.73)e–3 s = 7.7e–4 s
The total time of no switching for the converter due to a
soft-start event
= tDISCHARGE + tCHARGE = 1.85e–4 + 7.7e–4 = 9.55e–4 s
Example (2) Converter Output Rise Time
The rise time for the converter output to reach regulation
can be closely approximated as the time between the start
ofswitching(SS_MAXDC=VSS(ACTIVE))andthetimewhere
converter duty cycle is in regulation (DC(REG)) and no
longercontrolledbySS_MAXDC(SS_MAXDC=VSS(REG)).
Converter output rise time can be expressed as:
Output Rise Time = t(VSS(REG)) – t(VSS(ACTIVE))
Step1:DetermineconverterdutycycleDC(REG)foroutput
in regulation.
The natural duty cycle DC(REG) of the converter depends
on several factors. For this example it is assumed that
DC(REG) = 60% for power supply input voltage near the
power supply UVLO. This gives SD_VSEC = 1.32V.
Also assume that the maximum duty cycle clamp pro-
grammed for this condition is 72% for SS_MAXDC(DC)
= 1.84V, fOSC = 200kHz and RDELAY = 40k.
Step 2: Calculate VSS(REG)
To calculate the level of SS_MAXDC (VSS(REG)) that no
longer clamps the natural duty cycle of the converter, the
equation for maximum duty cycle clamp must be used
(see previous section Programming Maximum Duty Cycle
Clamp).
The point where the maximum duty cycle clamp meets
DC(REG) during soft-start is given by:
DC(REG) = Max Duty Cycle Clamp
0.6 = k 0.522(SS_MAXDC(DC)/SD_VSEC) – (tDELAY
fOSC)
For SD_VSEC = 1.32V, fOSC = 200kHz and
RDELAY = 40k
This gives k = 1 and tDELAY = 40ns.
Rearranging the above equation to solve for SS_MAXDC
= VSS(REG)
= [0.6 + (tDELAY fOSC)(SD_VSEC)]/(k 0.522)
= [0.6 + (40ns 200kHz)(1.32V)]/(1 0.522)
= (0.608)(1.32)/0.522 = 1.537V
Step 3: Calculate t(VSS(REG)) – t(VSS(ACTIVE))
Recall the time for SS_MAXDC to charge to a given volt-
age VSS is given by:
t = RCHARGE CSS (–1) ln(1 – VSS/SS_MAXDC(DC))
(Figure 16 gives the model for SS_MAXDC charging)
For RT = 35.7k, RB = 100k, RCHARGE = 26.3k
For CSS = 0.1F, this gives t(VSS(ACTIVE))
= t(VSS(0.8V)) = 2.63e4 1e–7 (–1) ln(1 – 0.8/1.84)
= 2.63e–3 (–1) ln(0.565) = 1.5e–3 s
t(VSS(REG)) = t(VSS(1.537V)) = 26.3k 0.1F –1
ln(1 – 1.66/1.84) = 2.63e–3 (–1) ln(0.146) = 5e–3 s
The rise time for the converter output:
= t(VSS(REG)) – t(VSS(ACTIVE)) = (5 – 1.5)e–3 s
= 3.5e–3 s
相关PDF资料 |
PDF描述 |
|---|---|
| LTC4269IDKD-2 | SWITCHING CONTROLLER, 560 kHz SWITCHING FREQ-MAX, PDSO32 |
| LTC4269CDKD-2 | SWITCHING CONTROLLER, 560 kHz SWITCHING FREQ-MAX, PDSO32 |
| LTC4269IDKD-2#TR | SWITCHING CONTROLLER, 560 kHz SWITCHING FREQ-MAX, PDSO32 |
| LTC4412IS6#TR | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO6 |
| LTC4412IS6#TRM | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO6 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC4269CDKD-2-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:IEEE 802.3at High Power PD and Synchronous Forward Controller with AUX Support |
| LTC4269IDKD-1#PBF | 功能描述:IC PD/OPTO FLYBACK CTRLR 32-DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 热交换 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:119 系列:- 类型:热交换控制器 应用:通用型，PCI Express? 内部开关:无 电流限制:- 电源电压:3.3V，12V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:80-TQFP 供应商设备封装:80-TQFP（12x12） 包装:托盘 产品目录页面:1423 (CN2011-ZH PDF) |
| LTC4269IDKD-1#TRPBF | 功能描述:IC PD/OPTO FLYBACK CTRLR 32-DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 热交换 系列:- 产品培训模块:Obsolescence Mitigation Program 标准包装:100 系列:- 类型:热插拔开关 应用:通用 内部开关:是 电流限制:可调 电源电压:9 V ~ 13.2 V 工作温度:-40°C ~ 150°C 安装类型:表面贴装 封装/外壳:10-WFDFN 裸露焊盘 供应商设备封装:10-TDFN-EP（3x3） 包装:管件 |
| LTC4269IDKD-1-PBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:IEEE 802.3at PD with Synchronous No-Opto Flyback Controller |
| LTC4269IDKD-1-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:IEEE 802.3at PD with Synchronous No-Opto Flyback Controller |
发布紧急采购，3分钟左右您将得到回复。