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参数资料
| 型号： | LTC3823EUH#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 10/26页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 32-QFN |
| 标准包装： | 73 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 1MHz |
| 占空比： | 90% |
| 电源电压： | 4.5 V ~ 36 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 ~ 85°C |
| 封装/外壳： | 32-WFQFN 裸露焊盘 |
| 包装： | 管件 |
LTC3823
OPERATION
Main Control Loop
The LTC3823 is a current mode controller for DC/DC
step-down converters. In normal operation, the top
MOSFET is turned on for a ?xed interval determined by
a one-shot timer, OST. When the top MOSFET is turned
off, the bottom MOSFET is turned on until the current
comparator I CMP trips, restarting the one-shot timer and
initiating the next cycle. Inductor current is determined
by sensing the voltage between the SENSE – and SENSE +
pins using a sense resistor or the bottom MOSFET on-
resistance . The voltage on the I TH pin sets the comparator
threshold corresponding to inductor valley current. The
error ampli?er EA adjusts this voltage by comparing the
feedback signal, V FB , to an internal reference voltage. If
the load current increases, it causes a drop in the feedback
voltage relative to the reference. The I TH voltage then rises
until the average inductor current again matches the load
current.
At low load currents, the inductor current can drop to zero
and become negative. This is detected by current reversal
comparator I REV which then shuts off M2, resulting in
discontinuous operation. Both switches will remain off
with the output capacitor supplying the load current until
the I TH voltage rises above the zero current level (0.75V)
to initiate another cycle. Discontinuous mode operation
is disabled by comparator F when the FCB pin is brought
below 0.6V, forcing continuous synchronous operation.
The operating frequency is determined implicitly by the
top MOSFET on-time and the duty cycle required to main-
tain regulation. The one-shot timer generates an on time
that is proportional to the ideal duty cycle, thus holding
frequency approximately constant with changes in V IN .
The nominal frequency can be adjusted with an external
resistor, R ON .
For applications with stringent constant frequency re-
quirements, the LTC3823 can be synchronized with an
external clock. By programming the nominal frequency
of the LTC3823 the same as the external clock frequency,
the LTC3823 behaves as a constant frequency part against
the load and supply variations.
Overvoltage and undervoltage comparators OV and UV
pull the PGOOD output low if the output feedback voltage
exits a ±10% window around the regulation point after the
internal 20μs power bad mask timer expires. Furthermore,
in an overvoltage condition, M1 is turned off and M2 is
turned on immediately and held on until the overvoltage
condition clears.
Foldback current limiting is provided if the output is shorted
to ground. As V FB drops, the buffered current threshold
voltage, I THB , is pulled down and clamped to 0.9V. This
reduces the inductor valley current level to one-tenth of its
maximum value as V FB approaches 0V. Foldback current
limiting is disabled at start-up.
Pulling the RUN pin low forces the controller into its
shutdown state, turning off both M1 and M2. Forcing a
voltage above 1.5V will turn on the device.
INTV CC Power
Power for the top and bottom MOSFET drivers and most of
the internal controller circuitry is derived from the INTV CC
pin. The top MOSFET driver is powered from a ?oating
bootstrap capacitor, C B . This capacitor is recharged from
INTV CC through an external Schottky diode, D B , when the
top MOSFET is turned off. If the input voltage is low and
INTV CC drops below 3V, undervoltage lockout circuitry
prevents the power switches from turning on.
3823fd
10
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3823IGN#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:2,000 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:1MHz 占空比:50% 电源电压:9 V ~ 10 V 降压:无 升压:是 回扫:是 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:8-TSSOP（0.173"，4.40mm 宽） 包装:带卷 (TR) |
| LTC3823IGN#PBF | 制造商:Linear Technology 功能描述:IC SYNC STEP-DOWN DC/DC CTRL SSOP-28 |
| LTC3823IGN#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 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 ~ 125°C 封装/外壳:24-WQFN 裸露焊盘 包装:带卷 (TR) |
| LTC3823IUH#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 32-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 特色产品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 标准包装:1 系列:PowerWise® PWM 型:电压模式 输出数:1 频率 - 最大:1MHz 占空比:81% 电源电压:4.5 V ~ 18 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:-5°C ~ 125°C 封装/外壳:32-WFQFN 裸露焊盘 包装:Digi-Reel® 产品目录页面:1303 (CN2011-ZH PDF) 其它名称:LM3754SQDKR |
| LTC3823IUH#PBF | 制造商:Linear Technology 功能描述:IC SYNC STEP-DOWN DC/DC CONTROLLER QFN32 |
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