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参数资料
| 型号： | LTM4601AHVMPV |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | SWITCHING REGULATOR, PBGA133 |
| 封装： | 15 X 15 MM, 2.82 MM HEIGHT, LEAD FREE, LGA-133 |
| 文件页数： | 13/30页 |
| 文件大小： | 519K |
| 代理商： | LTM4601AHVMPV |
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LTM4601AHV
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4601ahvfb
Example for 5V Output
LTM4601AHV minimum on-time = 100ns
tON = [(VOUT 10pF)/IfSET], for VOUT > 4.8V use 4.8V
LTM4601AHV minimum off-time = 400ns
tOFF = t – tON, where t = 1/Frequency
Duty Cycle = tON/t or VOUT/VIN
Equations for setting frequency:
IfSET = [VIN/(3 RfSET)], for 28V operation, IfSET = 238A,
tON = [(4.8 10pF)/IfSET], tON = 202ns, where the internal
RfSET is 39.2k. Frequency = [VOUT/(VIN tON)] = [5V/(28
202ns)] ~ 884kHz. The inductor ripple current begins to
get high at the higher input voltages due to a larger voltage
across the inductor. This is noted in the Inductor Ripple
Current vs Duty Cycle graph (Figure 3) where IL ≈ 10A at
20%dutycycle.Theinductorripplecurrentcanbelowered
at the higher input voltages by adding an external resistor
from fSET to ground to increase the switching frequency.
A 7A ripple current is chosen, and the total peak current
is equal to 1/2 of the 7A ripple current plus the output
current. The 5V output current is limited to 8A, so the
total peak current is less than 11.5A. This is below the
14A peak specified value. A 100k resistor is placed from
fSET to ground, and the parallel combination of 100k and
39.2k equates to 28k. The IfSET calculation with 28k and
28V input voltage equals 333A. This equates to a tON of
144ns. This will increase the switching frequency from
~884kHz to ~1.24MHz for the 28V to 5V conversion. The
minimum on time is above 100ns at 28V input. Since the
switching frequency is approximately constant over input
and output conditions, then the lower input voltage range
is limited to 10V for the 1.24MHz operation due to the
400ns minimum off time. Equation: tON = (VOUT/VIN) (1/
Frequency) equates to a 400ns on time, and a 400ns off
time. The VIN to VOUT Step-Down Ratio curves reflect an
operating range of 10V to 28V for 1.24MHz operation with
a 100k resistor to ground as shown in Figure 18, and an
8V to 16V operation for fSET floating. These modifications
are made to provide wider input voltage ranges for the 5V
output designs while limiting the inductor ripple current,
and maintaining the 400ns minimum off-time.
Example for 3.3V Output
LTM4601AHV minimum on-time = 100ns
tON = [(VOUT 10pF)/IfSET]
LTM4601AHV minimum off-time = 400ns
tOFF = t – tON, where t = 1/Frequency
Duty Cycle (DC) = tON/t or VOUT/VIN
Equations for setting frequency:
IfSET = [VIN/(3 RfSET)], for 28V operation, IfSET = 238A,
tON=[(3.310pF)/IfSET],tON=138.7ns,wheretheinternal
RfSETis39.2k.Frequency=[VOUT/(VINtON)]=[3.3V/(28
138.7ns)] ~ 850kHz. The minimum on-time and minimum
off-time are within specification at 139ns and 1037ns. The
4.5V minimum input for converting 3.3V output will not
meet the minimum off-time specification of 400ns. tON =
868ns, Frequency = 850kHz, tOFF = 315ns.
Solution
Lower the switching frequency at lower input voltages to
allow for higher duty cycles, and meet the 400ns minimum
off-timeat4.5Vinputvoltage.Theoff-timeshouldbeabout
500ns, which includes a 100ns guard band. The duty cycle
for (3.3V/4.5V) = ~73%. Frequency = (1 – DC)/tOFF or
(1 – 0.73)/500ns = 540kHz. The switching frequency
needs to be lowered to 540kHz at 4.5V input. tON = DC/
frequency, or 1.35s. The fSETpinvoltageis1/3ofVIN,and
the IfSET current equates to 38A with the internal 39.2k.
The IfSET current needs to be 24A for 540kHz operation.
As shown in Figure 19, a resistor can be placed from VOUT
to fSET to lower the effective IfSET current out of the fSET
pin to 24A. The fSET pin is 4.5V/3 =1.5V and VOUT = 3.3V,
therefore 130k will source 14A into the fSET node and
lower the IfSET current to 24A. This enables the 540kHz
operation and the 4.5V to 28V input operation for down
converting to 3.3V output. The frequency will scale from
540kHz to 1.1 MHz over this input range. This provides
for an effective output current of 8A over the input range.
applicaTions inForMaTion
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTM4601AHVMPV#3DJPBF | 制造商:Linear Technology 功能描述:DC to DC Converter and Switching Regulator Chip 制造商:LINEAR_TECH 功能描述: |
| LTM4601AHVMPV#PBF | 功能描述:IC DC/DC UMODULE 12A 133-LGA RoHS:是 类别:电源 - 板载 >> DC DC Converters 系列:µModule® 设计资源:Maxi/Mini/Micro Design Guide, Appl Manual 标准包装:1 系列:微型 类型:隔离 输出数:1 电压 - 输入（最小）:18V 电压 - 输入（最大）:36V Voltage - Output 1:48V Voltage - Output 2:- Voltage - Output 3:- 电流 - 输出（最大）:* 电源（瓦） - 制造商系列:100W 电压 - 隔离:* 特点:* 安装类型:通孔 封装/外壳:模块 尺寸/尺寸:2.28" L x 1.45" W x 0.62" H（57.9mm x 36.8mm x 15.7mm） 包装:散装 工作温度:-20°C ~ 100°C 效率:* 电源（瓦特）- 最大:* 其它名称:1102-1290V24C48C100BL-ND |
| LTM4601AHVMPV#PBF | 制造商:Linear Technology 功能描述:DC/DC Converter IC |
| LTM4601AHVMPV-PBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:12A, 28VIN DC/DC μModule with PLL, Output Tracking and Margining |
| LTM4601AHVMPY#PBF | 功能描述:IC DC/DC UMODULE 12A 133-BGA RoHS:是 类别:电源 - 板载 >> DC DC Converters 系列:µModule® 设计资源:VI-200, VI-J00 Design Guide, Appl Manual 标准包装:1 系列:* 类型:隔离 输出数:1 电压 - 输入（最小）:66V 电压 - 输入（最大）:160V Voltage - Output 1:12V Voltage - Output 2:- Voltage - Output 3:- 电流 - 输出（最大）:* 电源（瓦） - 制造商系列:50W 电压 - 隔离:* 特点:* 安装类型:通孔 封装/外壳:9-FinMod 尺寸/尺寸:4.60" L x 1.86" W x 0.79" H（116.8mm x 47.2mm x 20.1mm） 包装:散装 工作温度:-25°C ~ 85°C 效率:* 电源（瓦特）- 最大:* |
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