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| 型号： | LTC1876EG |
| 厂商： | Linear Technology |
| 文件页数： | 12/36页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BST PWM CM 36-SSOP |
| 标准包装： | 37 |
| 系列： | PolyPhase® |
| PWM 型： | 电流模式 |
| 输出数： | 3 |
| 频率 - 最大： | 360kHz |
| 占空比： | 99.4% |
| 电源电压： | 3.5 V ~ 36 V |
| 降压： | 是 |
| 升压： | 是 |
| 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 ~ 85°C |
| 封装/外壳： | 36-SSOP（0.209"，5.30mm 宽） |
| 包装： | 管件 |
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LTC1876
OPERATIO
(Refer to Functional Diagram)
cycles, followed by a variable “sleep” interval depending
upon the load current. The resultant output voltage ripple
is held to a very small value by having the hysteretic
comparator after the error amplifier gain block.
Constant Frequency Operation
When the FCB pin is tied to INTV CC , Burst Mode operation
is disabled and the forced minimum output current re-
quirement is removed. This provides constant frequency,
discontinuous (preventing reverse inductor current) cur-
rent operation over the widest possible output current
range. This constant frequency operation is not as efficient
as Burst Mode operation, but does provide a lower noise,
constant frequency operating mode down to approxi-
mately 1% of designed maximum output current.
Constant Current (PWM) Operation
Tying the FCB pin to ground will force continuous current
operation. This is the least efficient operating mode, but
may be desirable in certain applications. The output can
source or sink current in this mode. When sinking current
while in forced continuous operation, current will be
forced back into the main power supply potentially boost-
ing the input supply to dangerous voltage levels—
BEWARE!
Frequency Setting
The FREQSET pin provides frequency adjustment to the
controllers’ internal oscillator from approximately 140kHz
to 310kHz. This input is nominally biased through an
internal resistor to the 1.19V reference, setting the oscil-
lator frequency to approximately 220kHz. This pin can be
driven from an external AC or DC signal source to control
the instantaneous frequency of the oscillator. The auxillary
boost regulator operates at a constant 1.2MHz frequency.
INTV CC /EXTV CC Power
Power for the top and bottom MOSFET drivers and most
other internal circuitry is derived from the INTV CC pin.
When the EXTV CC pin is left open, an internal 5V low
dropout linear regulator supplies INTV CC power. If EXTV CC
is taken above 4.7V, the 5V regulator is turned off and an
internal switch is turned on connecting EXTV CC to INTV CC .
This allows the INTV CC power to be derived from a high
efficiency external source such as the output of the regu-
lator itself or a secondary winding, as described in Appli-
cations Information.
Standby Mode Pin
The STBYMD pin is a three-state input that controls
common circuitry within the IC as follows: When the
STBYMD pin is held at ground, both controller RUN/SS
pins are pulled to ground providing a single control pin to
shut down both controllers. When the pin is left open, the
internal RUN/SS currents are enabled to charge the
RUN/SS capacitor(s), allowing the turn-on of either con-
troller and activating necessary common internal biasing.
When the STBYMD pin is taken above 2V, both internal
linear regulators are turned on independent of the state of
the two switching regulator controllers, providing output
power to “wake-up” other circuitry. Decouple the pin with
a small capacitor (0.01 μ F) to ground if the pin is not
connected to a DC potential.
Output Overvoltage Protection
An overvoltage comparator, OV, guards against transient
overshoots (>7.5%) as well as other more serious condi-
tions that may overvoltage the output. In this case, the top
MOSFET is turned off and the bottom MOSFET is turned on
until the overvoltage condition is cleared.
Power Good (PGOOD) Pin
The PGOOD pin is connected to an open drain of an internal
MOSFET. The MOSFET turns on and pulls the pin low when
both the outputs are not within ± 7.5% of their nominal
output levels as determined by their resistive feedback
dividers. When both controller outputs meet the ± 7.5%
requirement, the MOSFET is turned off within 10 μ s and the
pin is allowed to be pulled up by an external resistor to a
source of up to 7V. The auxiliary regulator’s output is not
monitored.
Foldback Current, Short-Circuit Detection and Short-
Circuit Latchoff
The RUN/SS capacitors are used initially to limit the inrush
current of each step-down switching regulator. After the
1876fa
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| LTC1876EG#PBF | 功能描述:IC REG CTRLR BST PWM CM 36-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 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 |
| LTC1876EG#TR | 功能描述:IC REG CTRLR BST PWM CM 36-SSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 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 |
| LTC1876EG#TRPBF | 功能描述:IC REG CTRLR BST PWM CM 36-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 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 |
| LTC1877EMS8 | 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: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 |
| LTC1877EMS8#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 |
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