参数资料
| 型号： | ISL6236AIRZ-T |
| 厂商： | Intersil |
| 文件页数： | 34/37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页第33页当前第34页第35页第36页第37页
ISL6236A
PD ( Q H Resistance ) = ? ------------------------ ? ( I LOAD ) ? r DS ( ON )
Input Capacitor Selection
The input capacitors must meet the input-ripple-current
(I RMS ) requirement imposed by the switching current. The
? V OUT_ ? 2
? V IN ( MIN ) ?
(EQ. 19)
ISL6236A dual switching regulator operates at different
frequencies. This interleaves the current pulses drawn by
the two switches and reduces the overlap time where they
add together. The input RMS current is much smaller in
comparison than with both SMPSs operating in phase. The
input RMS current varies with load and the input voltage.
The maximum input capacitor RMS current for a single
SMPS is given by Equation 18:
Generally, a small high-side MOSFET reduces switching
losses at high input voltage. However, the r DS(ON) required
to stay within package power-dissipation limits often limits
how small the MOSFET can be. The optimum situation
occurs when the switching (AC) losses equal the conduction
(r DS(ON) ) losses.
Switching losses in the high-side MOSFET can become an
insidious heat problem when maximum battery voltage is
? V OUT ( V IN – V OUT_ ) ?
I RMS ≈ I LOAD ? ?
? V IN ?
------------------------------------------------------------
(EQ. 18)
applied, due to the squared term in the CV 2 f switching-loss
equation. Reconsider the high-side MOSFET chosen for
adequate r DS(ON) at low battery voltages if it becomes
PD ( Q H Switching ) = ( V IN ( MAX ) ) ? ----------------------------------------------------- ?
When V IN = 2 ? V OUT_ ( D = 50% ) , IRMS has maximum
current of I LOAD ? 2 .
The ESR of the input-capacitor is important for determining
capacitor power dissipation. All the power (I RMS2 x ESR)
heats up the capacitor and reduces efficiency. Nontantalum
chemistries (ceramic or OS-CON) are preferred due to their
low ESR and resilience to power-up surge currents. Choose
input capacitors that exhibit less than +10°C temperature
rise at the RMS input current for optimal circuit longevity.
Place the drains of the high-side switches close to each
other to share common input bypass capacitors.
Power MOSFET Selection
Most of the following MOSFET guidelines focus on the
challenge of obtaining high load-current capability (>5A)
when using high-voltage (>20V) AC adapters. Low-current
applications usually require less attention.
Choose a high-side MOSFET (Q 1 /Q 3 ) that has conduction
losses equal to the switching losses at the typical battery
extraordinarily hot when subjected to V IN(MAX) .
Calculating the power dissipation in NH (Q 1 /Q 3 ) due to
switching losses is difficult since it must allow for quantifying
factors that influence the turn-on and turn-off times. These
factors include the internal gate resistance, gate charge,
threshold voltage, source inductance, and PC board layout
characteristics. The following switching-loss calculation
provides only a very rough estimate and is no substitute for
bench evaluation, preferably including verification using a
thermocouple mounted on NH (Q 1 /Q 3 ):
2 ? C RSS ? f SW ? I LOAD ?
? I GATE ?
(EQ. 20)
where C RSS is the reverse transfer capacitance of Q H
(Q 1 /Q 3 ) and I GATE is the peak gate-drive source/sink
current.
For the synchronous rectifier, the worst-case power
dissipation always occurs at maximum battery voltage:
PD ( Q L ) = ? 1 – -------------------------- ? I LOAD ? r DS ( ON )
voltage for maximum efficiency. Ensure that the conduction
losses at the minimum input voltage do not exceed the
package thermal limits or violate the overall thermal budget.
? V OUT ? 2
? V IN ( MAX ) ?
(EQ. 21)
Ensure that conduction losses plus switching losses at the
maximum input voltage do not exceed the package ratings
or violate the overall thermal budget.
Choose a synchronous rectifier (Q 2 /Q 4 ) with the lowest
possible r DS(ON) . Ensure the gate is not pulled up by the
The absolute worst case for MOSFET power dissipation
occurs under heavy overloads that are greater than
I LOAD(MAX) but are not quite high enough to exceed the
current limit and cause the fault latch to trip. To protect
against this possibility, "overdesign" the circuit to tolerate:
high-side switch turning on due to parasitic drain-to-gate
capacitance, causing cross-conduction problems. Switching
I LOAD = I LIMIT ( HIGH ) + ( ( LIR ) ? 2 ) ? I LOAD ( MAX )
(EQ. 22)
losses are not an issue for the synchronous rectifier in the
buck topology since it is a zero-voltage switched device
when using the buck topology.
MOSFET Power Dissipation
Worst-case conduction losses occur at the duty-factor
extremes. For the high-side MOSFET, the worst-case power
dissipation (PD) due to the MOSFET's r DS(ON) occurs at the
minimum battery voltage, as shown in Equation 19:
34
where I LIMIT(HIGH) is the maximum valley current allowed
by the current-limit circuit, including threshold tolerance and
resistance variation.
Rectifier Selection
Current circulates from ground to the junction of both
MOSFETs and the inductor when the high-side switch is off.
As a consequence, the polarity of the switching node is
negative with respect to ground. This voltage is
approximately -0.7V (a diode drop) at both transition edges
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。