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参数资料
| 型号： | LTC3811EUHF#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 15/48页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 38-QFN |
| 标准包装： | 2,500 |
| 系列： | PolyPhase® |
| PWM 型： | 电流模式 |
| 输出数： | 2 |
| 频率 - 最大： | 850kHz |
| 占空比： | 90% |
| 电源电压： | 4.5 V ~ 30 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： | 38-WFQFN 裸露焊盘 |
| 包装： | 带卷 (TR) |
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LTC3811
OPERATION
Main Control Loop
(Refer to the Functional Diagram)
In addition to differences in pinout, another difference
The LTC3811 uses a constant frequency peak current
mode control architecture. During normal operation, the
top MOSFET is turned on each cycle when the oscillator
sets the PWM latch and turned off when the main current
comparator (ICMP) resets the latch. The peak current at
which comparator ICMP resets the latch is controlled by
the voltage on the COMP pin, which is the output of the
error ampli?er. The remote sense ampli?er (DIFFAMP)
produces a signal equal to the differential voltage sensed
across the output capacitor and re-references it to the
local IC ground reference (SGND). The FB pin receives
a portion of this voltage feedback signal and compares
it to the internal 0.6V reference. When the load current
increases it causes a slight decrease in the FB pin voltage
relative to the 0.6V reference, which in turn causes the
COMP pin voltage to rise until the average inductor current
is equal to the load current.
The top MOSFET drivers are biased from a ?oating boot-
strap capacitor, C B , which is normally recharged during
the off-time through an external Schottky diode. When V IN
decreases to a voltage close to V OUT , however, the loop
may enter dropout and attempt to turn on the top MOSFET
continuously. A dropout detector senses this condition and
forces the top MOSFET to turn off every 10th cycle for one
third of a cycle to recharge the bootstrap capacitor.
Differences Between the QFN and G36 Package
Options
The LTC3811 is offered in two package options, a 38-pin
QFN and a 36-pin SSOP. The full featured QFN package
option has no leads and an exposed lead frame that needs
between the two package options is their thermal resis-
tance. The QFN package, by virtue of its exposed lead
frame, has a junction-to-ambient thermal resistance of
only 34°C/W, whereas the SSOP package has a thermal
resistance of 100°C/W. The power dissipation of the IC
is a function of the input voltage, the gate charge of the
external power MOSFETs and the operating frequency.
The gate charge losses can be partially mitigated by us-
ing the EXTV CC input to supply power to the IC, but users
should beware that high input voltage applications using
very high gate charge power MOSFETs, that also need to
operate at high frequency, should only be attempted using
the QFN package option. More details covering thermal
management are given later in this data sheet.
Supplying Power to the LTC3811
The LTC3811 features several power supply input pins
and multiple ways of supplying power to the gate drivers
and low voltage analog control circuitry.
The ?rst method of supplying power to the IC uses the
internal low dropout linear regulator (LDO) that draws
power from V IN and regulates DRV CC to 6V, as shown in
Figure 1. The DRV CC input supplies power to the internal
gate drivers, which are capable of very high peak transient
charge (1A) and discharge (5A) currents. The DRV CC supply
should be decoupled to PGND with a minimum of 4.7μF
low ESR ceramic (X5R or better) capacitance. If multiple
power MOSFETs are being driven in parallel for high cur-
rent applications it is recommended that this capacitance
V IN
V IN
to be soldered to the PCB, whereas the 36-pin SSOP has
leads and is therefore slightly easier to solder to a PCB
EXTV CC
4.5V
+
–
6V
LDO
and to debug in the lab.
The primary electrical difference between the QFN and
DRV CC
SSOP options is the SSOP version lacks the CSOUT
and PHASEMODE pins. With no CSOUT pin, the SSOP
INTV CC
GATE DRIVER SUPPLY
ANALOG SUPPLY
version has no provision for output voltage positioning.
With no PHASEMODE input (it is internally connected
to SGND), the SSOP version is limited to 2-phase and
SGND
BIAS
V FB
SS/TRACK
0.600V
EA
3811 F01
4-phase applications.
Figure 1. Supplying Power to the LTC3811 from V IN
3811f
15
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| LTC3812EFE5#PBF | 制造商:Linear Technology 功能描述: |
| LTC3812EFE-5#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 16TSSOP 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 |
| LTC3812EFE-5#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 16TSSOP 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) |
| LTC3812IFE-5#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 16TSSOP 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) |
| LTC3812IFE-5#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 16TSSOP 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) |
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