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| 型号： | LTC3634EFE#PBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | 5.5 A DUAL SWITCHING CONTROLLER, 4600 kHz SWITCHING FREQ-MAX, PDSO28 |
| 封装： | 4.40 MM, LEAD FREE, PLASTIC, TSSOP-28 |
| 文件页数： | 5/28页 |
| 文件大小： | 359K |
| 代理商： | LTC3634EFE#PBF |
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LTC3634
13
3634f
Figure 3. Setting the Output Voltage
applicaTions inForMaTion
When RT is tied to INTVCC, the switching frequency will
default to approximately 2MHz, as set by an internal resis-
tor. This internal resistor is more sensitive to process and
temperature variations than an external resistor (see the
Typical Performance Characteristics section) and is best
used for applications where switching frequency accuracy
is not critical.
Output Voltage Programming
Each regulator’s output voltage is set by an external resis-
tive divider according to the following equation:
VOUT = VFBREG 1+
R2
R1
where VFBREG is the reference voltage as specified in the
Electrical Characteristics Table. The reference voltage is
600mV for channel 1; for channel 2 the reference voltage
is equal to the VTTR pin voltage. The desired output volt-
age is set by appropriate selection of resistors R1 and R2
as shown in Figure 3.
The buffered output voltage on the VTTR pin is nominally
equal to half of the VDDQIN voltage; thus configuring
VOUT2 as a VTT bus termination supply for DDR memory
is as simple as shorting VOUT2 to VFB2 and connecting
VDDQIN directly to the VOUT1 (the VDDQ supply).
Choosing large values for R1 and R2 will result in im-
proved zero-load efficiency but may lead to undesirable
noise coupling or phase margin reduction due to stray
capacitances at the VFB node. Care should be taken to
route the VFB trace away from any noise source, such as
the SW trace.
The LTC3634 controlled on-time architecture is optimized
for an output voltage range of 0.6V to 3V, which is suitable
forpoweringDDRmemory.TheLTC3634iscapableofregu-
lating higher output voltages; however, controlled on-time
behaviorisnotensured.Whentheoutputvoltageisgreater
than 3V, the step-down regulator is forced to increase the
switching frequency in order to achieve output regulation.
Furthermore, external clock synchronization is no longer
possible, and channel 2 cannot maintain 90°/180° phase
operation with respect to channel 1. In short, the LTC3634
will behave like a constant on-time regulator instead of a
controlled on-time regulator. Therefore, output voltages
greater than 3V should only be used in applications where
switchingfrequencyandchannel-to-channelphase-locking
are not critical performance characteristics.
Inductor Selection
Foragiveninputandoutputvoltage,theinductorvalueand
operatingfrequencydeterminetheinductorripplecurrent.
More specifically, the inductor ripple current decreases
with higher inductor value or higher operating frequency
according to the following equation:
IL =
VOUT
f L
1
VOUT
VIN
whereΔIL=inductorripplecurrent,f=operatingfrequency
and L = inductor value. A trade-off between component
size, efficiency and operating frequency can be seen from
this equation. Accepting larger values of ΔIL allows the
use of lower value inductors but results in greater inductor
LTC3634
R2
CF
(OPTIONAL)
VOUT
3634 F03
VFB
SGND
R1
Figure 2. Switching Frequency vs RT
0
FREQUENCY
(kHz)
1000
2000
3000
5000
200
700
600
3634 F02
0
6000
4000
100
300 400 500
RT RESISTOR (k)
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3634EUFD#PBF | 功能描述:IC CONV DDR DDR2 DDR3 28QFN 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 |
| LTC3634EUFD#TRPBF | 功能描述:IC CONV DDR DDR2 DDR3 28QFN 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 |
| LTC3634HFE#PBF | 制造商:Linear Technology 功能描述:IC CONV DDR DDR2 DDR3 28TSSOP 制造商:Linear Technology 功能描述:BUCK 15V 3A 500KHZ-4MHZ TS 制造商:Linear Technology 功能描述:DP-SWREG/Monolithic, 15V Dual 3A Monolithic Step Down Regulator for DDR Power 制造商:Linear Technology 功能描述:DC-DC REGULATOR, BUCK, ADJ, TSSOP-28, Primary Input Voltage:15V, No. of Outputs:2, Output Current:3A, No. of Pins:28, Operating Temperature Min:-40C, Operating Temperature Max:150C, MSL:MSL 1 - Unlimited, Package / Case:28-TSSOP , RoHS Compliant: Yes |
| LTC3634HFE#TRPBF | 制造商:Linear Technology 功能描述:IC REG 15V 3A STEP DOWN 28-TSSOP |
| LTC3634HUFD#PBF | 制造商:Linear Technology 功能描述:IC CONV DDR DDR2 DDR3 28-QFN 制造商:Linear Technology 功能描述:BUCK 15V 3A 500KHZ-4MHZ QF 制造商:Linear Technology 功能描述:DC-DC REGULATOR, BUCK, ADJ, QFN-28, Primary Input Voltage:15V, No. of Outputs:2, Output Current:3A, No. of Pins:28, Operating Temperature Min:-40C, Operating Temperature Max:150C, MSL:MSL 1 - Unlimited, Package / Case:28-QFN , RoHS Compliant: Yes |
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