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参数资料
| 型号： | LTC1877IMS8#TRPBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | 1.5 A SWITCHING REGULATOR, 605 kHz SWITCHING FREQ-MAX, PDSO8 |
| 封装： | LEAD FREE, PLASTIC, MSOP-8 |
| 文件页数： | 2/16页 |
| 文件大小： | 234K |
| 代理商： | LTC1877IMS8#TRPBF |
LTC1877
10
1877fa
pacitors. The POSCAP solid electrolytic capacitor available
from Sanyo is an excellent choice for output bulk capacitors
due to its low ESR/size ratio. Once the ESR requirement
for COUT has been met, the RMS current rating generally
far exceeds the IRIPPLE(P-P) requirement.
When using tantalum capacitors, it is critical that they are
surge tested for use in switching power supplies. A good
choice is the AVX TPS series of surface mount tantalum,
available in case heights ranging from 2mm to 4mm. Other
capacitor types include KEMET T510 and T495 series and
Sprague 593D and 595D series. Consult the manufacturer
for other specic recommendations.
Output Voltage Programming
The output voltage is set by a resistive divider according
to the following formula:
VV
R
OUT =+
08
1
2
1
.
(2)
The external resistive divider is connected to the output,
allowing remote voltage sensing, as shown in Figure 3.
The output of the phase detector is a pair of complementary
current sources charging or discharging the external lter
network on the PLL LPF pin. The relationship between the
voltage on the PLL LPF pin and operating frequency is
shown in Figure 4. A simplied block diagram is shown
in Figure 5.
If the external frequency (VSYNC/MODE) is greater than
550kHz, the center frequency, current is sourced con-
tinuously, pulling up the PLL LPF pin. When the external
frequency is less than 550kHz, current is sunk continuously,
pulling down the PLL LPF pin. If the external and internal
frequencies are the same but exhibit a phase difference,
the current sources turn on for an amount of time cor-
responding to the phase difference. Thus, the voltage on
the PLL LPF pin is adjusted until the phase and frequency
of the external and internal oscillators are identical. At
Figure 3. Setting the LTC1877 Output Voltage
VFB
GND
LTC1877
0.8V
VOUT 10V
R2
R1
1877 F03
Figure 4. Relationship Between Oscillator
Frequency and Voltage at PLL LPF Pin
Figure 5. Phase-Locked Loop Block Diagram
0
0.4
0.8
1.2
1.6
2.0
800
700
600
500
400
300
OSCILLA
TOR
FREQUENCY
(kHz)
V
PLL LPF (V)
1877 F04
SYNC/
MODE
PHASE
DETECTOR
DIGITAL
PHASE/
FREQUENCY
DETECTOR
2.4V
RLP
CLP
VCO
1877 F05
PLL LPF
Phase-Locked Loop and Frequency Synchronization
The LTC1877 has an internal voltage-controlled oscillator
and phase detector comprising a phase-locked loop. This
allows the top MOSFET turn-on to be locked to the rising
edge of an external frequency source. The frequency range
of the voltage-controlled oscillator is 400kHz to 700kHz.
The phase detector used is an edge sensitive digital type
that provides zero degrees phase shift between the external
and internal oscillators. This type of phase detector will
not lock up on input frequencies close to the harmonics
of the VCO center frequency. The PLL hold-in range ΔfH is
equal to the capture range, ΔfH = ΔfC = ±150kHz.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC1878EMS8 | 功能描述:IC REG BUCK SYNC ADJ 0.6A 8MSOP RoHS:否 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:升压（升压） 输出类型:可调式 输出数:1 输出电压:1.24 V ~ 30 V 输入电压:1.5 V ~ 12 V PWM 型:电流模式，混合 频率 - 开关:600kHz 电流 - 输出:500mA 同步整流器:无 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) 供应商设备封装:8-SOIC |
| LTC1878EMS8#PBF | 功能描述:IC REG BUCK SYNC ADJ 0.6A 8MSOP 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 |
| LTC1878EMS8#TR | 功能描述:IC REG BUCK SYNC ADJ 0.6A 8MSOP RoHS:否 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:升压（升压） 输出类型:可调式 输出数:1 输出电压:1.24 V ~ 30 V 输入电压:1.5 V ~ 12 V PWM 型:电流模式，混合 频率 - 开关:600kHz 电流 - 输出:500mA 同步整流器:无 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) 供应商设备封装:8-SOIC |
| LTC1878EMS8#TRPBF | 功能描述:IC REG BUCK SYNC ADJ 0.6A 8MSOP 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:升压（升压） 输出类型:可调式 输出数:1 输出电压:1.24 V ~ 30 V 输入电压:1.5 V ~ 12 V PWM 型:电流模式，混合 频率 - 开关:600kHz 电流 - 输出:500mA 同步整流器:无 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) 供应商设备封装:8-SOIC |
| LTC1878EMS8PBF | 制造商:Linear Technology 功能描述: 制造商:Linear Technology 功能描述:DC-DC Converter Step-Down 2.65-6V MSOP8 |
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