参数资料
| 型号： | LTC3831EGN |
| 厂商： | Linear Technology |
| 文件页数： | 11/20页 |
| 文件大小： | 0K |
| 描述： | IC SW REG CONTROLLR SYNC 16-SSOP |
| 标准包装： | 100 |
| 应用： | 控制器，DDR |
| 输入电压： | 3 V ~ 8 V |
| 输出数： | 1 |
| 输出电压： | 1.27 V ~ 4 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-SSOP（0.154"，3.90mm 宽） |
| 供应商设备封装： | 16-SSOP |
| 包装： | 管件 |
| 产品目录页面： | 1336 (CN2011-ZH PDF) |
LTC3831
APPLICATIONS INFORMATION
supply input) by at least one power MOSFET V GS(ON) for
SHDN
ef?cient operation. An internal level shifter allows PV CC1 to
operate at voltages above V CC and V IN , up to 14V maximum.
This higher voltage can be supplied with a separate supply,
or it can be generated using a charge pump.
TRADITIONAL
SYNC METHOD
WITH EARLY
RAMP
TERMINATION
200kHz
FREE RUNNING
RAMP SIGNAL
RAMP SIGNAL
WITH EXT SYNC
Gate drive for the bottom MOSFET Q2 is provided through
PV CC2 . This supply only need to be above the power MOSFET
V GS(ON) for ef?cient operation. PV CC2 can also be driven
from the same supply/charge pump for the PV CC1 , or it can
be connected to a lower supply to improve ef?ciency.
Figure 6 shows a doubling charge pump circuit that can be
RAMP AMPLITUDE
ADJUSTED
LTC3831
KEEPS RAMP
AMPLITUDE
CONSTANT
UNDER SYNC
Figure 4. External Synchronization Operation
3831 F04
used to provide 2V IN gate drive for Q1. The charge pump
consists of a Schottky diode from V IN to PV CC1 and a 0.1μF
capacitor from PV CC1 to the switching node at the drain of
Q2. This circuit provides 2V IN – V F to PV CC1 while Q1 is
ON and V IN – V F while Q1 is OFF where V F is the forward
voltage of the Schottky diode. Ringing at the drain of Q2
can cause transients above 2V IN at PV CC1 ; if V IN is higher
V CC
PV CC2
PV CC1
V IN
controller feedback loop. As a result, the loop crossover
frequency increases and it may cause the feedback loop
TG
Q1
to be unstable if the phase margin is insuf?cient.
To overcome this problem, the LTC3831 monitors the
peak voltage of the ramp signal and adjust the oscillator
INTERNAL
CIRCUITRY
BG
Q2
L O
+
V OUT
C OUT
charging current to maintain a constant ramp peak.
Input Supply Considerations/Charge Pump
The LTC3831 requires four supply voltages to operate: V IN
for the main power input, PV CC1 and PV CC2 for MOSFET
gate drive and a clean, low ripple V CC for the LTC3831
LTC3831
Figure 5. Supplies Input
V IN
3831 F05
internal circuitry (Figure 5).
In many applications, V CC can be powered from V IN
through an RC ?lter. This supply can be as low as 3V. The
low quiescent current (typically 800μA) allows the use
of relatively large ?lter resistors and correspondingly
small ?lter capacitors. 100Ω and 4.7μF usually provide
OPTIONAL
USE FOR V IN ≥ 7V
D Z
12V
1N5242
PV CC2
PV CC1
TG
MBR0530T1
0.1μF
Q1
L O
V OUT
adequate ?ltering for V CC . For best performance, connect
the 4.7μF bypass capacitor as close to the LTC3831 V CC
pin as possible.
LTC3831
BG
Q2
+
C OUT
3831 F06a
Gate drive for the top N-channel MOSFET Q1 is supplied
from PV CC1 . This supply must be above V IN (the main power
Figure 6. Doubling Charge Pump
3831fb
11
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| LTC3831EGN#PBF | 功能描述:IC SW REG CONTROLLR SYNC 16-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 专用型 系列:- 标准包装:43 系列:- 应用:控制器，Intel VR11 输入电压:5 V ~ 12 V 输出数:1 输出电压:0.5 V ~ 1.6 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:48-VFQFN 裸露焊盘 供应商设备封装:48-QFN（7x7） 包装:管件 |
| LTC3831EGN#TR | 功能描述:IC SW REG CONTROLLR SYNC 16-SSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - 专用型 系列:- 标准包装:43 系列:- 应用:控制器，Intel VR11 输入电压:5 V ~ 12 V 输出数:1 输出电压:0.5 V ~ 1.6 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:48-VFQFN 裸露焊盘 供应商设备封装:48-QFN（7x7） 包装:管件 |
| LTC3831EGN#TRPBF | 功能描述:IC SW REG CONTROLLR SYNC 16-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 专用型 系列:- 标准包装:43 系列:- 应用:控制器，Intel VR11 输入电压:5 V ~ 12 V 输出数:1 输出电压:0.5 V ~ 1.6 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:48-VFQFN 裸露焊盘 供应商设备封装:48-QFN（7x7） 包装:管件 |
| LTC3831EGN-1 | 功能描述:IC CTRLR SW REG SYNC DDR 16SSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - 专用型 系列:- 标准包装:43 系列:- 应用:控制器，Intel VR11 输入电压:5 V ~ 12 V 输出数:1 输出电压:0.5 V ~ 1.6 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:48-VFQFN 裸露焊盘 供应商设备封装:48-QFN（7x7） 包装:管件 |
| LTC3831EGN-1#PBF | 功能描述:IC CTRLR SW REG SYNC DDR 16SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 专用型 系列:- 标准包装:43 系列:- 应用:控制器，Intel VR11 输入电压:5 V ~ 12 V 输出数:1 输出电压:0.5 V ~ 1.6 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:48-VFQFN 裸露焊盘 供应商设备封装:48-QFN（7x7） 包装:管件 |
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