参数资料
| 型号： | LTC3735EUHF |
| 厂商： | Linear Technology |
| 文件页数： | 21/32页 |
| 文件大小： | 0K |
| 描述： | IC CTRLR DC/DC 2PH HI EFF 38-QFN |
| 标准包装： | 52 |
| 应用： | 控制器，Intel 移动式 CPU |
| 输出数： | 1 |
| 输出电压： | 0.7 V ~ 1.71 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 38-WFQFN 裸露焊盘 |
| 供应商设备封装： | 38-QFN（5x7） |
| 包装： | 管件 |
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LTC3735
APPLICATIONS INFORMATION
t ON ( MIN ) <
R SENSE R3
AVP ? –35.5 ? ? ,
if g m ? R3 > 10 ? OUT
R AVP ?
35.5 ? R3 ? R SENSE
MinimumOn-TimeConsiderations
Minimum on-time, t ON(MIN) , is the smallest time duration
that the LTC3735 is capable of turning on the top MOSFET.
It is determined by internal timing delays and the gate
charge required to turn on the top MOSFET. Low duty
cycle applications may approach this minimum on-time
limit and care should be taken to ensure that:
V OUT
V IN ( f )
If the duty cycle falls below what can be accommodated
by the minimum on-time, the LTC3735 will begin to skip
cycles resulting in variable frequency operation. The output
voltage will continue to be regulated, but the ripple current
and ripple voltage will increase.
m R AVP
(9)
V
0.6V
where R SENSE is the current sense resistor, m is the number
of phases, (m = 2 for LTC3735) R3 and R AVP are defined
in Figure 9. g m is the transconductance gain for the error
amplifier, it is about 4.5mmho for LTC3735. Rewriting
Equation 9 we can estimate the AVP resistor to be:
(10)
m ? | AVP|
V OUT+
The minimum on-time for the LTC3735 is generally less
than 150ns. However, as the peak sense voltage decreases,
the minimum on-time gradually increases. This is of par-
ticular concern in forced continuous applications with low
ripple current at light loads. If the duty cycle drops below
the minimum on-time limit in this situation, a significant
amount of cycle skipping can occur with correspondingly
larger ripple current and ripple voltage.
R2
R1
R3
V OA+
V OA–
R AVP
+
–
OAOUT
If an application can operate close to the minimum
on-time limit, an inductor must be chosen that has a low
enough inductance to provide sufficient ripple amplitude
to meet the minimum on-time requirement. As a general
rule, keep the inductor ripple current of each phase equal
to or greater than 15% of I OUT(MAX) at V IN(MAX) .
VID
0.6V
FB
–
+
I TH
3735 F09
R SENSE R3 R
if g m ? R3 >> OUT
ActiveVoltagePositioning
Active voltage positioning can be used to minimize peak-to-
peak output voltage excursion under worst-case transient
loading conditions. The open-loop DC gain of the control
loop is reduced depending upon the maximum load step
specifications. Active voltage positioning can easily be
added to the LTC3735. Figure 9 shows the equivalent circuit
for implementing AVP. The load line slope is estimated to be:
Figure 9. Simplified Schematic Diagram
for AVP Design in LTC3735
We also adopt the current sense resistors as part of
voltage positioning slopes. So the total load line slope is
estimated to be:
AVP ? –35.5 ? ? – SENSE ,
m R AVP m
(11)
V
0.6V
3735fa
21
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相关代理商/技术参数 |
参数描述 |
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| LTC3735EUHF#PBF | 功能描述:IC CTRLR DC/DC 2PH HI EFF 38-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 专用型 系列:- 标准包装:2,000 系列:- 应用:控制器，DSP 输入电压:4.5 V ~ 25 V 输出数:2 输出电压:最低可调至 1.2V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:30-TFSOP（0.173"，4.40mm 宽） 供应商设备封装:30-TSSOP 包装:带卷 (TR) |
| LTC3735EUHF#TR | 功能描述:IC CTRLR DC/DC 2PH HI EFF 38-QFN 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 |
| LTC3735EUHF#TRPBF | 功能描述:IC CTRLR DC/DC 2PH HI EFF 38-QFN 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 |
| LTC3736EGN | 功能描述:IC REG CTRLR BUCK PWM CM 24-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: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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