- 您现在的位置：买卖IC网 > PDF目录14136 > LTC1627CS8#TR (Linear Technology)IC REG BUCK SYNC ADJ 0.5A 8SOIC PDF资料下载
参数资料
| 型号： | LTC1627CS8#TR |
| 厂商： | Linear Technology |
| 文件页数： | 6/16页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK SYNC ADJ 0.5A 8SOIC |
| 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： | 0.8 V ~ 8.5 V |
| 输入电压： | 2.65 V ~ 8.5 V |
| PWM 型： | 电流模式，混合 |
| 频率 - 开关： | 35kHz ~ 350kHz |
| 电流 - 输出： | 500mA |
| 同步整流器： | 是 |
| 工作温度： | 0°C ~ 70°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 |
LTC1627
OPERATIO
Main Control Loop
(Refer to Functional Diagram)
output load exceeds 100mA. The threshold voltage be-
The LTC1627 uses a constant frequency, current mode
step-down architecture. Both the main and synchronous
switches, consisting of top P-channel and bottom
N-channel power MOSFETs, are internal. During normal
operation, the internal top power MOSFET is turned on
each cycle when the oscillator sets the RS latch, and
turned off when the current comparator, I COMP , resets the
RS latch. The peak inductor current at which I COMP resets
the RS latch is controlled by the voltage on the I TH pin,
which is the output of error amplifier EA. The V FB pin,
described in the Pin Functions section, allows EA to
receive an output feedback voltage from an external resis-
tive divider. When the load current increases, it causes a
slight decrease in the feedback voltage relative to the 0.8V
reference, which, in turn, causes the I TH voltage to in-
crease until the average inductor current matches the new
load current. While the top MOSFET is off, the bottom
MOSFET is turned on until either the inductor current
starts to reverse as indicated by the current reversal
comparator I RCMP , or the beginning of the next cycle.
The main control loop is shut down by pulling the RUN/SS
pin low. Releasing RUN/SS allows an internal 2.25 μ A
current source to charge soft-start capacitor C SS . When
C SS reaches 0.7V, the main control loop is enabled with the
I TH voltage clamped at approximately 5% of its maximum
value. As C SS continues to charge, I TH is gradually
released, allowing normal operation to resume.
Comparator OVDET guards against transient overshoots
> 7.5% by turning the main switch off and turning the
synchronous switch on. With the synchronous switch
turned on, the output is crowbarred. This may cause a
large amount of current to flow from V IN if the main switch
is damaged, blowing the system fuse.
Burst Mode Operation
The LTC1627 is capable of Burst Mode operation in which
the internal power MOSFETs operate intermittently based
on load demand. To enable Burst Mode operation, simply
allow the SYNC/FCB pin to float or connect it to a logic
high. To disable Burst Mode operation and enable forced
continuous mode, connect the SYNC/FCB pin to GND. In
this mode, the efficiency is lowest at light loads, but
becomes comparable to Burst Mode operation when the
6
tween Burst Mode operation and forced continuous mode
is 0.8V. This can be used to assist in secondary winding
regulation as described in Auxiliary Winding Control Using
SYNC/FCB Pin in the Applications Information section.
When the converter is in Burst Mode operation, the peak
current of the inductor is set to approximately 200mA,
even though the voltage at the I TH pin indicates a lower
value. The voltage at the I TH pin drops when the inductor’s
average current is greater than the load requirement. As
the I TH voltage drops below 0.12V, the BURST comparator
trips, causing the internal sleep line to go high and turn off
both power MOSFETs.
In sleep mode, both power MOSFETs are held off and the
internal circuitry is partially turned off, reducing the quies-
cent current to 200 μ A. The load current is now being
supplied from the output capacitor. When the output
voltage drops, causing I TH to rise above 0.22V, the top
MOSFET is again turned on and this process repeats.
Short-Circuit Protection
When the output is shorted to ground, the frequency of the
oscillator is reduced to about 35kHz, 1/10 the nominal
frequency. This frequency foldback ensures that the
inductor current has more time to decay, thereby prevent-
ing runaway. The oscillator’s frequency will progressively
increase to 350kHz (or the synchronized frequency) when
V FB rises above 0.3V.
Frequency Synchronization
The LTC1627 can be synchronized with an external
TTL/CMOS compatible clock signal. The frequency range
of this signal must be from 385kHz to 525kHz. Do not
attempt to synchronize the LTC1627 below 385kHz as this
may cause abnormal operation and an undesired fre-
quency spectrum. The top MOSFET turn-on follows the
rising edge of the external source.
When the LTC1627 is clocked by an external source, Burst
Mode operation is disabled; the LTC1627 then operates in
PWM pulse skipping mode. In this mode, when the output
load is very low, current comparator I COMP remains tripped
for more than one cycle and forces the main switch to stay
off for the same number of cycles. Increasing the output
相关PDF资料 |
PDF描述 |
|---|---|
| LTC1503IS8-2#TRPBF | IC REG BUCK SWITCHD CAP 2V 8SOIC |
| LTC1503IS8-2#TR | IC REG BUCK SWITCHD CAP 2V 8SOIC |
| LTC1503IS8-1.8#TR | IC REG BUCK SWITCHED CAP 8SOIC |
| HSM18DRXI | CONN EDGECARD 36POS DIP .156 SLD |
| HMM18DRXI | CONN EDGECARD 36POS DIP .156 SLD |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC1627IS8 | 功能描述:IC REG BUCK SYNC ADJ 0.5A 8SOIC 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: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 |
| LTC1627IS8#PBF | 功能描述:IC REG BUCK SYNC ADJ 0.5A 8SOIC 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 |
| LTC1627IS8#TR | 功能描述:IC REG BUCK SYNC ADJ 0.5A 8SOIC 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: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 |
| LTC1627IS8#TRPBF | 功能描述:IC REG BUCK SYNC ADJ 0.5A 8SOIC 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 |
| LTC1628CG | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
发布紧急采购，3分钟左右您将得到回复。