参数资料
| 型号： | ISL6308ACRZ |
| 厂商： | Intersil |
| 文件页数： | 18/28页 |
| 文件大小： | 0K |
| 描述： | IC CTRLR PWM BUCK 3PHASE 40-QFN |
| 标准包装： | 500 |
| 应用： | 控制器，DDR |
| 输入电压： | 5 V ~ 12 V |
| 输出数： | 1 |
| 输出电压： | 0.6 V ~ 2.3 V |
| 工作温度： | 0°C ~ 70°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 40-VFQFN 裸露焊盘 |
| 供应商设备封装： | 40-QFN（6x6） |
| 包装： | 管件 |
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ISL6308A
Overtemperature Protection
The ISL6308A constantly monitors the temperature of the
die. If it exceeds the Thermal Shutdown Setpoint
(thermal set ), both the controller and the output drivers will be
disabled, shutting down the output. Once the die
temperature cools to the Thermal Recovery Setpoint
(thermal rec ), the ISL6308A will go through an initialization
and soft-start, and attempt to resume normal operation. The
LOWER MOSFET POWER CALCULATION
The calculation for the approximate power loss in the lower
MOSFET can be simplified, since virtually all of the loss in
the lower MOSFET is due to current conducted through the
channel resistance (r DS(ON) ). In Equation 14, I M is the
maximum continuous output current, I PP is the peak-to-peak
inductor current (see Equation 1), and d is the duty cycle
(V OUT /V IN ).
· ? I M ? 2 I L , PP ? ( 1 – d )
P LOW , 1 = r DS ( ON ) ? ? ------ ? ? ( 1 – d ) + -------------------------------------
timing of the on/off cycles depends on the ambient
temperature, the thermal mounting of the IC package and
the FETs on the board, airflow, and other thermal
considerations.
? N ? 12
(EQ. 14)
P LOW , 2 = V D ( ON ) ? F SW ? ? ------ + --------- ? ? t d1 + ? ------ – --------- ? ? t d2
Note that both trip points (nominal 160°C and 135°C ) are
well beyond the maximum ambient temperature, over which
the specifications are guaranteed. Running continuously
above the rated temperature can degrade the life of the IC.
The OTP circuit is designed to protect the IC and system
from an occasional excursion; it should not be allowed as
part of normal operation or testing.
General Design Guide
This design guide is intended to provide a high-level
explanation of the steps necessary to create a multi-phase
power converter. It is assumed that the reader is familiar with
many of the basic skills and techniques referenced in the
following. In addition to this guide, Intersil provides complete
reference designs that include schematics, bills of materials,
and example board layouts for many applications.
Power Stages
The first step in designing a multi-phase converter is to
determine the number of phases. This determination
depends heavily on the cost analysis which in turn depends
on system constraints that differ from one design to the next.
Principally, the designer will be concerned with whether
components can be mounted on both sides of the circuit
board, whether through-hole components are permitted, the
total board space available for power-supply circuitry, and
the maximum amount of load current. Generally speaking,
the most economical solutions are those in which each
phase handles between 25A and 30A. All surface-mount
designs will tend toward the lower end of this current range.
If through-hole MOSFETs and inductors can be used, higher
per-phase currents are possible. In cases where board
space is the limiting constraint, current can be pushed as
high as 40A per phase, but these designs require heat sinks
and forced air to cool the MOSFETs, inductors and heat
An additional term can be added to the lower-MOSFET loss
equation to account for additional loss accrued during the
dead time when inductor current is flowing through the
lower-MOSFET body diode. This term is dependent on the
diode forward voltage at I M , V D(ON) , the switching
frequency, F SW , and the length of dead times, t d1 and t d2 , at
the beginning and the end of the lower-MOSFET conduction
interval respectively.
I M I PP I M I PP
? N 2 ? ? N 2 ?
(EQ. 15)
The total maximum power dissipated in each lower MOSFET
is approximated by the summation of P LOW,1 and P LOW,2 .
UPPER MOSFET POWER CALCULATION
In addition to r DS(ON) losses, a large portion of the upper
MOSFET losses are due to currents conducted across the
input voltage (V IN ) during switching. Since a substantially
higher portion of the upper-MOSFET losses are dependent
on switching frequency, the power calculation is more
complex. Upper MOSFET losses can be divided into
separate components involving the upper-MOSFET
switching times, the lower-MOSFET body-diode reverse
recovery charge, Q rr , and the upper MOSFET r DS(ON)
conduction loss.
When the upper MOSFET turns off, the lower MOSFET does
not conduct any portion of the inductor current until the
voltage at the phase node falls below ground. Once the
lower MOSFET begins conducting, the current in the upper
MOSFET falls to zero as the current in the lower MOSFET
ramps up to assume the full inductor current. In Equation 16,
the required time for this commutation is t 1 and the
approximated associated power loss is P UP,1 .
I M
I PP
P UP , 1 ≈ V IN ? ? ------ + --------- ? ? ? ---- 1 ? ? F SW
dissipating surfaces.
MOSFETs
The choice of MOSFETs depends on the current each
MOSFET will be required to conduct, the switching frequency,
the capability of the MOSFETs to dissipate heat, and the
availability and nature of heat sinking and air flow.
18
? N 2 ? ? 2 ?
? t ?
(EQ. 16)
FN6669.0
September 9, 2008
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相关代理商/技术参数 |
参数描述 |
|---|---|
| ISL6308ACRZR5609 | 制造商:Intersil Corporation 功能描述:PB-FREE DAC-LESS MULTI-PHASE PWM CONTR W/3-DRIVERS, HARD WI - Rail/Tube |
| ISL6308ACRZ-T | 功能描述:IC CTRLR PWM BUCK 3PHASE 40-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 |
| ISL6308ACRZ-TR5609 | 制造商:Intersil Corporation 功能描述:PB-FREE DAC-LESS MULTI-PHASE PWM CONTR W/3-DRIVERS, HARD WIR - Tape and Reel |
| ISL6308AEVAL1Z | 功能描述:EVALUATION BOARD FOR ISL6308A RoHS:是 类别:编程器，开发系统 >> 评估板 - DC/DC 与 AC/DC（离线）SMPS 系列:- 产品培训模块:Obsolescence Mitigation Program 标准包装:1 系列:True Shutdown™ 主要目的:DC/DC，步升 输出及类型:1，非隔离 功率 - 输出:- 输出电压:- 电流 - 输出:1A 输入电压:2.5 V ~ 5.5 V 稳压器拓扑结构:升压 频率 - 开关:3MHz 板类型:完全填充 已供物品:板 已用 IC / 零件:MAX8969 |
| ISL6308AIRZ | 功能描述:IC CTRLR PWM BUCK 3PHASE 40-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 |
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