参数资料
| 型号： | ISL6236AIRZ-T |
| 厂商： | Intersil |
| 文件页数： | 33/37页 |
| 文件大小： | 0K |
| 描述： | IC MAIN PWR CTRLR QUAD 32-QFN |
| 产品培训模块： | Solutions for Industrial Control Applications |
| 标准包装： | 6,000 |
| 应用： | 控制器，笔记本电脑电源系统 |
| 输入电压： | 4.5 V ~ 25 V |
| 输出数： | 4 |
| 输出电压： | 多重 |
| 工作温度： | -40°C ~ 100°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 32-VFQFN 裸露焊盘 |
| 供应商设备封装： | 32-QFN 裸露焊盘（5x5） |
| 包装： | 带卷 (TR) |
第1页第2页第3页第4页第5页第6页第7页第8页第9页第10页第11页第12页第13页第14页第15页第16页第17页第18页第19页第20页第21页第22页第23页第24页第25页第26页第27页第28页第29页第30页第31页第32页当前第33页第34页第35页第36页第37页
ISL6236A
Inductor Selection
The switching frequency (on-time) and operating point
(% ripple or LIR) determine the inductor value using
Examining the 5A circuit example with a maximum
r DS(ON) = 5m Ω at room temperature. At +125°C reveals the
following:
V OUT_ ( V IN + V OUT_ )
V IN ? f ? LIR ? I LOAD ( MAX )
L = ----------------------------------------------------------------- = 8.3 μ H
Equation 8:
L = ---------------------------------------------------------------------
Example: I LOAD(MAX) = 5A, V IN = 12V, V OUT2 = 5V,
f = 200kHz, 35% ripple current or LIR = 0.35:
5V ( 12V – 5V )
12V ? 200kHz ? 0.35 ? 5A
(EQ. 8)
(EQ. 9)
I LIMIT ( LOW ) = ( 25mV ) ? ( ( 5m Ω × 1.2 ) > 5A – ( 0.35 ? 2 ) 5A )
(EQ. 13)
4.17A > 4.12A (EQ. 14)
4.17A is greater than the valley current of 4.12A, so the
circuit can easily deliver the full-rated 5A using the 30mV
nominal current-limit threshold voltage.
Output Capacitor Selection
Find a low-loss inductor having the lowest possible DC
resistance that fits in the allotted dimensions. Ferrite cores
are often the best choice. The core must be large enough
not to saturate at the peak inductor current (IPEAK) shown in
Equation 10:
The output filter capacitor must have low enough equivalent
series resistance (ESR) to meet output ripple and
load-transient requirements, yet have high enough ESR to
satisfy stability requirements. The output capacitance must
also be high enough to absorb the inductor energy while
IPEAK = I LOAD ( MAX ) + [ ( LIR ? 2 ) ? I LOAD ( MAX ) ]
(EQ. 10)
transitioning from full-load to no-load conditions without
tripping the overvoltage fault latch. In applications where the
The inductor ripple current also impacts transient response
performance, especially at low V IN - V OUT differences. Low
inductor values allow the inductor current to slew faster,
replenishing charge removed from the output filter capacitors
output is subject to large load transients, the output
capacitor's size depends on how much ESR is needed to
prevent the output from dipping too low under a load
transient. Ignoring the sag due to finite capacitance:
R SER ≤ ----------------------------------
by a sudden load step. The peak amplitude of the output
transient (VSAG) is also a function of the maximum duty
factor, which can be calculated from the on-time and
V DIP
I LOAD ( MAX )
(EQ. 15)
minimum off-time:
where V DIP is the maximum-tolerable transient voltage drop.
( Δ I LOAD ( MAX ) ) ? L ? K ? ------------------- + t OFF ( MIN ) ? ?
2 ? C OUT ? V OUT K ? -------------------------------- ? - t
R ESR ≤ -----------------------------------------------
V P – P
L IR ? I LOAD ( MAX )
2 ? ? V OUT_ ? ?
? ? V IN ? ?
VSAG = ----------------------------------------------------------------------------------------------------------------------------
? V IN – V OUT ?
? V IN ? OFF ( MIN )
(EQ. 11)
In non-CPU applications, the output capacitor's size
depends on how much ESR is needed to maintain an
acceptable level of output voltage ripple:
(EQ. 16)
where minimum off-time = 0.35μs (max) and K is from
Table 2.
Determining the Current Limit
The minimum current-limit threshold must be great enough
to support the maximum load current when the current limit
is at the minimum tolerance value. The valley of the inductor
current occurs at I LOAD(MAX) minus half of the ripple
current; therefore:
where V P-P is the peak-to-peak output voltage ripple. The
actual capacitance value required relates to the physical size
needed to achieve low ESR, as well as to the chemistry of
the capacitor technology. Thus, the capacitor is usually
selected by ESR and voltage rating rather than by
capacitance value (this is true of tantalum, OS-CON, and
other electrolytic-type capacitors).
When using low-capacity filter capacitors such as polymer
types, capacitor size is usually determined by the capacity
I LIMIT ( LOW ) > I LOAD ( MAX ) – [ ( LIR ? 2 ) ? I LOAD ( MAX ) ]
(EQ. 12)
required to prevent V SAG and V SOAR from tripping the
undervoltage and overvoltage fault latches during load
I PEAK ? L
V SOAR = ------------------------------------------------
2 ? C OUT ? V OUT_
where: I LIMIT(LOW) = minimum current-limit threshold
voltage divided by the r DS(ON) of Q 2 /Q 4 .
Use the worst-case maximum value for r DS(ON) from the
MOSFET Q 2 /Q 4 data sheet and add some margin for the
rise in r DS(ON) with temperature. A good general rule is to
allow 0.2% additional resistance for each °C of temperature
rise.
33
transients in ultrasonic mode.
For low input-to-output voltage differentials (V IN / V OUT < 2),
additional output capacitance is required to maintain stability
and good efficiency in ultrasonic mode. The amount of
overshoot due to stored inductor energy can be calculated
as shown in Equation 17:
2
(EQ. 17)
where I PEAK is the peak inductor current.
FN6453.3
March 18, 2008
相关PDF资料 |
PDF描述 |
|---|---|
| EBA32DTKT | CONN EDGECARD 64POS DIP .125 SLD |
| MIC5335-PGYMT TR | IC REG LDO 3V/1.8V .3A 6-MLF |
| ISL6236IRZA-TR5281 | IC MAIN PWR CTRLR QUAD 32-QFN |
| ESA18DTKS | CONN EDGECARD 36POS DIP .125 SLD |
| ISL6524ACBZA-T | IC CTRLR VRM8.5 PWM TRPL 28-SOIC |
相关代理商/技术参数 |
参数描述 |
|---|---|
| ISL6236EVAL1 | 功能描述:EVAL BOARD 1 FOR ISL6236 RoHS:否 类别:编程器，开发系统 >> 评估板 - 线性稳压器 (LDO) 系列:* 产品变化通告:1Q2012 Discontinuation 30/Mar/2012 设计资源:NCP590MNDPTAGEVB Gerber Files 标准包装:1 系列:- 每 IC 通道数:2 - 双 输出电压:1.8V，2.8V 电流 - 输出:300mA 输入电压:2.1 ~ 5.5 V 稳压器类型:正，固定式 工作温度:-40°C ~ 85°C 板类型:完全填充 已供物品:板 已用 IC / 零件:NCP590MNDP 其它名称:NCP590MNDPTAGEVB-NDNCP590MNDPTAGEVBOS |
| ISL6236EVAL2 | 功能描述:EVAL BOARD 2 FOR ISL6236 RoHS:否 类别:编程器，开发系统 >> 评估板 - 线性稳压器 (LDO) 系列:* 产品变化通告:1Q2012 Discontinuation 30/Mar/2012 设计资源:NCP590MNDPTAGEVB Gerber Files 标准包装:1 系列:- 每 IC 通道数:2 - 双 输出电压:1.8V，2.8V 电流 - 输出:300mA 输入电压:2.1 ~ 5.5 V 稳压器类型:正，固定式 工作温度:-40°C ~ 85°C 板类型:完全填充 已供物品:板 已用 IC / 零件:NCP590MNDP 其它名称:NCP590MNDPTAGEVB-NDNCP590MNDPTAGEVBOS |
| ISL6236IRZA | 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:High-Efficiency, Quad-Output, Main Power Supply Controllers for Notebook Computers |
| ISL6236IRZAR5281 | 功能描述:IC MAIN PWR CTRLR QUAD 32-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 |
| ISL6236IRZA-T | 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:High-Efficiency, Quad-Output, Main Power Supply Controllers for Notebook Computers |
发布紧急采购，3分钟左右您将得到回复。