参数资料
| 型号： | ISL6540AIRZA-T |
| 厂商： | Intersil |
| 文件页数： | 20/22页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM VM 28-QFN |
| 产品培训模块： | Solutions for Industrial Control Applications |
| 标准包装： | 1 |
| PWM 型： | 电压模式 |
| 输出数： | 1 |
| 频率 - 最大： | 2MHz |
| 占空比： | 100% |
| 电源电压： | 2.97 V ~ 22 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： | 28-VFQFN 裸露焊盘 |
| 包装： | 标准包装 |
| 产品目录页面： | 1243 (CN2011-ZH PDF) |
| 其它名称： | ISL6540AIRZA-TDKR |
ISL6540A
However, the equivalent series inductance (ESL) of these
capacitors increases with case size and can reduce the
0.6
usefulness of the capacitor to high slew-rate transient
loading. Unfortunately, ESL is not a specified parameter.
Work with your capacitor supplier and measure the
capacitor ’s impedance with frequency to select a suitable
component. In most cases, multiple electrolytic capacitors of
small case size perform better than a single large case
capacitor.
Output Inductor Selection
The output inductor is selected to meet the output voltage
0.5
0.4
0.3
0.2
0.1
Δ I LOUT = 0.5 x I out
Δ I LOUT = 0.25 x I out
Δ I LOUT = 0
ripple requirements and minimize the converter ’s response
time to the load transient. The inductor value determines the
converter ’s ripple current and the ripple voltage is a function
0.0
0
0.1 0.2
0.3 0.4 0.5 0.6 0.7
0.8 0.9 1.0
of the ripple current. The ripple voltage and current are
approximated by Equation 19:
DUTY CYCLE (D)
FIGURE 11. INPUT-CAPACITOR CURRENT MULTIPLIER FOR
V IN - V OUT V OUT
Δ I = -------------------------------- ? ----------------
F S x L V IN
Δ V OUT = Δ I × ESR
(EQ. 19)
SINGLE-PHASE BUCK CONVERTER
to supply the current needed each time Q 1 turns on. Place the
small ceramic capacitors physically close to the MOSFETs
Increasing the value of inductance reduces the ripple current
and voltage. However, the large inductance values reduce
the converter ’s response time to a load transient.
One of the parameters limiting the converter ’s response to a
load transient is the time required to change the inductor
current. Given a sufficiently fast control loop design, the
ISL6540A will provide either 0% or 100% duty cycle in
response to a load transient. The response time is the time
required to slew the inductor current from an initial current
value to the transient current level. During this interval the
difference between the inductor current and the transient
and between the drain of Q 1 and the source of Q 2 .
The important parameters for the bulk input capacitor are the
voltage rating and the RMS current rating. For reliable
operation, select the bulk capacitor with voltage and current
ratings above the maximum input voltage and largest RMS
current required by the circuit. The capacitor voltage rating
should be at least 1.25x greater than the maximum input
voltage and a voltage rating of 1.5x is a conservative
guideline. The RMS current rating requirement for the input
capacitor of a buck regulator is approximated in Equation 21.
I O ( D – D 2 ) + -------- D
V O
current level must be supplied by the output capacitor.
Minimizing the response time can minimize the output
capacitance required.
I IN , RMS =
OR
2 Δ I 2
12
D = ----------
VIN
The response time to a transient is different for the
application of load and the removal of load. Equation 20
gives the approximate response time interval for application
I
INRMS
= K ICM ? I O
(EQ. 21)
and removal of a transient load:
For a through-hole design, several electrolytic capacitors
(Panasonic HFQ series or Nichicon PL series or Sanyo
t RISE = --------------------------------
t FALL = -------------------------------
L O × I TRAN
V IN – V OUT
L O × I TRAN
V OUT
(EQ. 20)
MV-GX or equivalent) may be needed. For surface mount
designs, solid tantalum capacitors can be used, but caution
where: I TRAN is the transient load current step, t RISE is the
response time to the application of load, and t FALL is the
response time to the removal of load. With a lower input
source such as 1.8V or 3.3V, the worst case response time
can be either at the application or removal of load and
dependent upon the output voltage setting. Be sure to check
both of these equations at the minimum and maximum
output levels for the worst case response time.
Input Capacitor Selection
Use a mix of input bypass capacitors to control the voltage
overshoot across the MOSFETs. Use small ceramic
capacitors for high frequency decoupling and bulk capacitors
20
must be exercised with regard to the capacitor surge current
rating. These capacitors must be capable of handling the
surge-current at power-up. Figure 11 provides an easy
graphical approximation of the input RMS requirements for a
single-phase buck converter.
MOSFET Selection/Considerations
The ISL6540A requires 2 N-Channel power MOSFETs.
These should be selected based upon r DS(ON) , gate supply
requirements, and thermal management requirements.
In high-current applications, the MOSFET power dissipation,
package selection and heatsink are the dominant design
factors. The power dissipation includes two loss
FN6288.5
October 7, 2008
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相关代理商/技术参数 |
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| ISL6540AIRZR5359 | 制造商:Rochester Electronics LLC 功能描述: 制造商:Intersil Corporation 功能描述: |
| ISL6540AIRZ-T | 功能描述:IC REG CTRLR BUCK PWM VM 28-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:275kHz 占空比:50% 电源电压:18 V ~ 110 V 降压:无 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:是 工作温度:-40°C ~ 85°C 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) |
| ISL6540AIRZ-TR5359 | 制造商:Intersil Corporation 功能描述: |
| ISL6540AIRZ-TR5453 | 制造商:Intersil Corporation 功能描述:STD. ISL6540AIRZ-T WITH GOLD BOND WIRE ONLY - Tape and Reel |
| ISL6540CRZ | 制造商:Intersil Corporation 功能描述:VOLT MODE PWM CNTRLR 0.6V TO 20V 30A 28QFN EP - Rail/Tube |
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