- 您现在的位置：买卖IC网 > PDF目录13936 > LT3688EUF#PBF (Linear Technology)IC REG BUCK ADJ 0.8A DL 24QFN PDF资料下载
参数资料
| 型号： | LT3688EUF#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 23/28页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK ADJ 0.8A DL 24QFN |
| 标准包装： | 91 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 2 |
| 输出电压： | 0.8 V ~ 32.4 V |
| 输入电压： | 3.8 V ~ 36 V |
| PWM 型： | 电流模式，Burst Mode? |
| 频率 - 开关： | 500kHz ~ 2.1MHz |
| 电流 - 输出： | 800mA |
| 同步整流器： | 无 |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 24-WFQFN 裸露焊盘 |
| 包装： | 管件 |
| 供应商设备封装： | 24-QFN（4x4） |
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页第22页当前第23页第24页第25页第26页第27页第28页
LT3688
APPLICATIONS INFORMATION
C POR = t RST ? 200 ?
? ms ? ?
C WDT = t WDU ? 50 ?
? ms ? ?
? pF ?
This equation is accurate for reset timeout periods of 1ms,
or greater. To program faster timeout periods, see the
Reset Timeout Period vs Capacitance graph in the Typical
Characteristics section. Leaving the C POR pin unconnected
will generate a minimum reset timeout of approximately
65μs. Maximum reset timeout is limited by the largest
available low leakage capacitor. The accuracy of the
timeout period will be affected by capacitor leakage (the
nominal charging current is 2.5μA), capacitor tolerance
and temperature coef?cient. A low leakage, low tempco,
capacitor is recommended.
Selecting the Watchdog Timing Capacitor
The watchdog timeout period is adjustable and can be
optimized for software execution. The watchdog window
upper boundary, t WDU is adjusted by connecting a capacitor,
C WDT , between the C WDT pin and ground. Given a speci?ed
watchdog timeout period, the capacitor is determined by:
? pF ?
The window lower boundary (t WDL ) and the watchdog
timeout (t WDTO ) have a ?xed relationship to t WDU for a
given capacitor. The window lower boundary is related to
t WDU by the following:
Shorted and Reversed Input Protection
If an inductor is chosen to prevent excessive saturation, the
LT3688 will tolerate a shorted output. When operating in
short-circuit condition, the LT3688 will reduce its frequency
until the valley current is at a typical value of 1.2A (see Figure
12). There is another situation to consider in systems where
the output will be held high when the input to the LT3688 is
absent. This may occur in battery charging applications or
in battery backup systems where a battery or some other
supply is diode ORed with the LT3688’s output. If the V IN
pin is allowed to ?oat and the EN/UVLO pin is held high
(either by a logic signal or because it is tied to V IN ), then
the LT3688’s internal circuitry will pull its quiescent current
through its SW pin. This is ?ne if the system can tolerate a
few mA in this state. If the EN/UVLO pin is grounded, the
SW pin current will drop to essentially zero.
However, if the V IN pin is grounded while the output is
held high, then parasitic diodes inside the LT3688 can
pull large currents from the output through the SW pin
and the V IN pin. Figure 13 shows a circuit that will run
only when the input voltage is present and that protects
against a shorted or reversed input.
V SW
10V/DIV
t WDL =
1
16
? t WDU
I L
500mA/DIV
The watchdog timeout is related to t WDU by the following:
5μs/DIV
3688 F12
t WDTO = ? t WDU
1
8
Leaving the C WDT pin unconnected will generate a minimum
watchdog window upper boundary of approximately 200μs.
Maximum window upper boundary is limited by the largest
available low leakage capacitor. The timing accuracy of the
reset and watchdog signals depends on the initial accuracy
and stability of the programing capacitors. Use capacitors
with speci?ed accuracy, leakage and voltage and temperature
coef?cients. For surface mount ceramic capacitors C0G and
NP0 types are superior to alternatives such as X5R and X7R.
Figure 12. The LT3688 Reduces Its Frequency to Below
70kHz to Protect Against Shorted Output with 36V Input
PCB Layout
For proper operation and minimum EMI, care must be taken
during printed circuit board layout. Figure 14 shows the
recommended component placement with trace, ground
plane and via locations. Note that large, switched currents
?ow in the LT3688’s V IN , DA and SW pins, the catch diode
(D1) and the input capacitor (C1). The loop formed by
3688f
23
相关PDF资料 |
PDF描述 |
|---|---|
| LT3689IUD-5#TRPBF | IC REG BUCK 5V 0.7A 16QFN |
| RCC36DCMH-S288 | CONN EDGECARD 72POS .100 EXTEND |
| RCC36DCMD-S288 | CONN EDGECARD 72POS .100 EXTEND |
| EBC43DCST-S288 | CONN EDGECARD 86POS .100 EXTEND |
| RCC31DCAH-S189 | CONN EDGECARD 62POS R/A .100 SLD |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LT3688HFE#PBF | 功能描述:IC REG BUCK ADJ 0.8A DL 24TSSOP 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:MIC23xxx HyperLight Load™ Regulators 标准包装:5,000 系列:HyperLight Load® 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.8V 输入电压:2.7 V ~ 5.5 V PWM 型:混合物 频率 - 开关:4MHz 电流 - 输出:2A 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:8-VFDFN 裸露焊盘，8-MLF? 包装:带卷 (TR) 供应商设备封装:8-MLF?（2x2） 产品目录页面:1094 (CN2011-ZH PDF) 其它名称:576-3303-2 |
| LT3688HFE#TRPBF | 功能描述:IC REG BUCK ADJ 0.8A DL 24TSSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 设计资源:Design Support Tool 标准包装:1 系列:- 类型:升压（升压） 输出类型:固定 输出数:1 输出电压:3V 输入电压:0.75 V ~ 2 V PWM 型:- 频率 - 开关:- 电流 - 输出:100mA 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:SOT-23-5 细型，TSOT-23-5 包装:剪切带 (CT) 供应商设备封装:TSOT-23-5 其它名称:AS1323-BTTT-30CT |
| LT3688HFEPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual 800mA Step-Down Switching Regulator with Power-On Reset |
| LT3688IFE#PBF | 功能描述:IC REG BUCK ADJ 0.8A DL 24TSSOP 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:MIC23xxx HyperLight Load™ Regulators 标准包装:5,000 系列:HyperLight Load® 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.8V 输入电压:2.7 V ~ 5.5 V PWM 型:混合物 频率 - 开关:4MHz 电流 - 输出:2A 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:8-VFDFN 裸露焊盘，8-MLF? 包装:带卷 (TR) 供应商设备封装:8-MLF?（2x2） 产品目录页面:1094 (CN2011-ZH PDF) 其它名称:576-3303-2 |
| LT3688IFE#TRPBF | 功能描述:IC REG BUCK ADJ 0.8A DL 24TSSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 设计资源:Design Support Tool 标准包装:1 系列:- 类型:升压（升压） 输出类型:固定 输出数:1 输出电压:3V 输入电压:0.75 V ~ 2 V PWM 型:- 频率 - 开关:- 电流 - 输出:100mA 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:SOT-23-5 细型，TSOT-23-5 包装:剪切带 (CT) 供应商设备封装:TSOT-23-5 其它名称:AS1323-BTTT-30CT |
发布紧急采购，3分钟左右您将得到回复。