参数资料
型号: IR3621FTR
厂商: International Rectifier
文件页数: 12/29页
文件大小: 0K
描述: IC REG CTRLR BUCK PWM VM 28TSSOP
产品变化通告: (EP) Parts Discontinuation 25/May/2012
标准包装: 0
PWM 型: 电压模式
输出数: 2
频率 - 最大: 345kHz
占空比: 86.5%
电源电压: 5.5 V ~ 14.5 V
降压:
升压:
回扫:
反相:
倍增器:
除法器:
Cuk:
隔离:
工作温度: -40°C ~ 125°C
封装/外壳: 28-TSSOP(0.173",4.40mm 宽)
包装: 标准包装
产品目录页面: 1383 (CN2011-ZH PDF)
配用: IRDC3621-ND - BOARD EVAL DUAL SYNC BUCK CTRLR
其它名称: IR3621FDKR
IR3621 & (PbF)
I RMS = (I 1 D 1 (1-D 1 )+I D 2 (1-D 2 )-2I 1 I 2 D 1 D 2 ) --- (6)
? I O
Input Capacitor Selection
The 180 0 out of phase will reduce the RMS value of the
ripple current seen by input capacitors. This reduces
numbers of input capacitors. The input capacitors must
be selected that can handle both the maximum ripple
RMS at highest ambient temperature as well as the
maximum input voltage. The RMS value of current ripple
for duty cycles under 50% is expressed by:
2 2
2
Where:
I RMS is the RMS value of the input capacitor current
D 1 and D 2 are the duty cycle for each output
I 1 and I 2 are the current for each output
For this application the I RMS =4.8A
For higher efficiency, low ESR capacitors are recom-
mended.
Choose two Poscap from Sanyo 16TPB47M (16V, 47 μ F,
70m ? ) with a maximum allowable ripple current of 1.4A
for inputs of each channel.
Inductor Selection
The inductor is selected based on operating frequency,
transient performance and allowable output voltage ripple.
Low inductor values result in faster response to step
load (high ? i/ ? t) and smaller size but will cause larger
output ripple due to increased inductor ripple current. As
a rule of thumb, select an inductor that produces a ripple
current of 10-40% of full load DC.
For the buck converter, the inductor value for desired
operating ripple current can be determined using the fol-
lowing relation:
For ? i (1.8V) = 35%(I O(1.8V) ), then the output inductor will
be:
L 3 = 1.1 μ H
Panasonic provides a range of inductors in different val-
ues and low profile for large currents.
Choose ETQP6F1R1BFA (1.1 μ H, 16A, 2.2m ? ) both for
L 3 and L 4.
For 2-phase application, equation (7) can be used for
calculating the inductors value. In such case the induc-
tor ripple current is usually chosen to be between 10-
40% of maximum phase current.
Output Capacitor Selection
The criteria to select the output capacitor is normally
based on the value of the Effective Series Resistance
(ESR). In general, the output capacitor must have low
enough ESR to meet output ripple and load transient
requirements, yet have high enough ESR to satisfy sta-
bility requirements. The ESR of the output capacitor is
calculated by the following relationship:
(ESL, Equivalent Series Inductance is neglected)
? V O
ESR ≤ ---(8)
Where:
? V O = Output Voltage Ripple
? i = Inductor Ripple Current
? V O = 3% of V O will result to ESR (2.5V) =16.6m ? and
ESR (1.8V) =16m ?
The Sanyo TPC series, Poscap capacitor is a good choice.
The 6TPC330M, 330 μ F, 6.3V has an ESR 40m ? . Se-
lecting three of these capacitors in parallel for 2.5V out-
put, results to an ESR of ? 13.3m ? which achieves our
low ESR goal. And selecting three of these capacitors in
parallel for 1.8V output, results in an ESR of ? 13.3m ?
V IN - V OUT = L ×
? i
? t
; ? t = D ×
1
f S
;D=
V OUT
V IN
which achieves our low ESR goal.
The capacitors value must be high enough to absorb the
L = (V IN - V OUT ) ×
V OUT
V IN ×? i × f S
---(7)
inductor's ripple current.
Where:
V IN = Maximum Input Voltage
V OUT = Output Voltage
? i = Inductor Ripple Current
f S = Switching Frequency
? t = Turn On Time
D = Duty Cycle
For ? i (2.5V) = 45%(I O(2.5V) ), then the output inductor will
be:
L 4 = 1.1 μ H
Power MOSFET Selection
The IR3621 uses four N-Channel MOSFETs. The selec-
tion criteria to meet power transfer requirements is based
on maximum drain-source voltage (V DSS ), gate-source
drive voltage (V GS ), maximum output current, On-resis-
tance R DS(ON) and thermal management.
The both control and synchronous MOSFETs must have
a maximum operating voltage (V DSS ) that exceeds the
maximum input voltage (V IN ).
12
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IR3621MPBF 功能描述:IC REG CTRLR BUCK PWM VM 32MLPQ 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:4,000 系列:- PWM 型:电压模式 输出数:1 频率 - 最大:1.5MHz 占空比:66.7% 电源电压:4.75 V ~ 5.25 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:40-VFQFN 裸露焊盘 包装:带卷 (TR)
IR3621MTR 功能描述:IC REG CTRLR BUCK PWM VM 32MLPQ 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
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