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| 型号： | LT3689EMSE-5#TRPBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | 1.95 A SWITCHING REGULATOR, 2160 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封装： | LEAD FREE, PLASTIC, MSOP-16 |
| 文件页数： | 6/32页 |
| 文件大小： | 2188K |
| 代理商： | LT3689EMSE-5#TRPBF |
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LT3689/LT3689-5
14
3689fd
Maximum Operating Voltage
The maximum input voltage for LT3689 applications
depends on switching frequency, the absolute maximum
ratings of the VIN and BST pins, and by the minimum
duty cycle (DCMIN). The LT3689 can operate from input
voltages up to 36V, and safely withstand input transient
voltages up to 60V. Note that while VIN > 38V (typical),
the LT3689 will stop switching, allowing the output to fall
out of regulation.
DCMIN = tON(MIN) fSW
where tON(MIN) is equal to 130ns (for TJ > 125°C tON(MIN)
is equal to 150ns) and fSW is the switching frequency.
Running at a lower switching frequency allows a lower
minimum duty cycle. The maximum input voltage before
pulse-skipping occurs depends on the output voltage and
the minimum duty cycle:
VIN(PS) =
VOUT + VD
DCMIN
– VD + VSW
Example: fSW = 790kHz, VOUT = 3.3V,
DCMIN = 130ns 790kHz = 0.103
VIN(PS) =
3.3V + 0.4V
0.103
– 0.4V + 0.4V = 36V
The LT3689 will regulate the output current at input volt-
ages greater than VIN(PS). For example, an application
with an output voltage of 1.8V and switching frequency
of 1.5MHz has a VIN(PS) of 11.3V, as shown in Figure 1.
Figure 2 shows operation at 24V. Output ripple and peak
inductor current have significantly increased. A saturating
inductor may further reduce performance. For input volt-
ages over 30V, there are restrictions on the inductor size
and saturation rating. See the Inductor Selection section
formoredetails.Inpulse-skippingmode,theLT3689skips
switchingpulsestomaintainoutputregulation.Above38V
(typical) switching will stop. Transients of up to 60V are
acceptable, regardless of switching frequency.
Minimum Operating Voltage Range
The minimum input voltage is determined either by the
LT3689’s minimum operating voltage of ~3.4V or by its
maximum duty cycle. The duty cycle is the fraction of
time that the internal switch is on and is determined by
the input and output voltages:
DC =
VOUT + VD
VIN – VSW + VD
Unlike many fixed frequency regulators, the LT3689 can
extend its duty cycle by remaining on for multiple cycles.
TheLT3689willnotswitchoffattheendofeachclockcycle
if there is sufficient voltage across the boost capacitor (C3
in the Block Diagram). Eventually, the voltage on the boost
capacitor falls and requires refreshing. Circuitry detects
APPLICATIONS INFORMATION
Figure 1. Operation Below VIN(PS). VIN = 10V,
VOUT = 1.8V and fSW = 1.5MHz
Figure 2. Operation Above VIN(PS). VIN = 24V,
VOUT = 1.8V and fSW = 1.5MHz. Output Ripple
and Peak Inductor Current Increase
5s/DIV
VOUT
50mV/DIV
(AC)
IL
0.5A/DIV
3689 F01
5s/DIV
VOUT
50mV/DIV
(AC)
IL
0.5A/DIV
3689 F02
相关PDF资料 |
PDF描述 |
|---|---|
| LT3689EUD-5#TRPBF | 1.95 A SWITCHING REGULATOR, 2160 kHz SWITCHING FREQ-MAX, PQCC16 |
| LT3689EMSE-5#PBF | 1.95 A SWITCHING REGULATOR, 2160 kHz SWITCHING FREQ-MAX, PDSO16 |
| LT3689IUD-5#TRPBF | 1.95 A SWITCHING REGULATOR, 2160 kHz SWITCHING FREQ-MAX, PQCC16 |
| LT3689IMSE-5#TRPBF | 1.95 A SWITCHING REGULATOR, 2160 kHz SWITCHING FREQ-MAX, PDSO16 |
| LT3692IUH#TRPBF | 5.8 A DUAL SWITCHING CONTROLLER, 2750 kHz SWITCHING FREQ-MAX, PQCC32 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LT3689EMSE-PBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:700mA Step-Down Regulator with Power-On Reset and Watchdog Timer |
| LT3689EMSE-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:700mA Step-Down Regulator with Power-On Reset and Watchdog Timer |
| LT3689EUD#PBF | 功能描述:IC REG BUCK ADJ 0.7A 16QFN 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 |
| LT3689EUD#TRPBF | 功能描述:IC REG BUCK ADJ 0.7A 16QFN 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:2,500 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V，1.5V，1.8V，2.5V 输入电压:2.7 V ~ 20 V PWM 型:- 频率 - 开关:- 电流 - 输出:50mA 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:10-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 包装:带卷 (TR) 供应商设备封装:10-MSOP 裸露焊盘 |
| LT3689EUD-5#PBF | 功能描述:IC REG BUCK 5V 0.7A 16QFN 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:2,500 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V，1.5V，1.8V，2.5V 输入电压:2.7 V ~ 20 V PWM 型:- 频率 - 开关:- 电流 - 输出:50mA 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:10-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 包装:带卷 (TR) 供应商设备封装:10-MSOP 裸露焊盘 |
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