参数资料
| 型号： | ISL6323BCRZ |
| 厂商： | Intersil |
| 文件页数： | 26/36页 |
| 文件大小： | 0K |
| 描述： | IC PWM CTRLR SYNC BUCK DL 48QFN |
| 标准包装： | 43 |
| 应用： | 控制器，AMD SVI |
| 输入电压： | 5 V ~ 12 V |
| 输出数： | 2 |
| 输出电压： | 最高 2V |
| 工作温度： | 0°C ~ 70°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 |
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页当前第26页第27页第28页第29页第30页第31页第32页第33页第34页第35页第36页
ISL6323B
the capability of the MOSFETs to dissipate heat, and the
availability and nature of heat sinking and air flow.
LOWER MOSFET POWER CALCULATION
The calculation for power loss in the lower MOSFET is
A third component involves the lower MOSFET
reverse-recovery charge, Q rr . Since the inductor current has
fully commutated to the upper MOSFET before the
lower-MOSFET body diode can recover all of Q rr , it is
conducted through the upper MOSFET across VIN. The
simple, since virtually all of the loss in the lower MOSFET is
due to current conducted through the channel resistance
(r DS(ON) ). In Equation 21, I M is the maximum continuous
power dissipated as a result is P UP,3 .
P UP , 3 = V IN ? Q rr ? f S
(EQ. 25)
output current, I P-P is the peak-to-peak inductor current
(see Equation 2), and d is the duty cycle (V OUT /V IN ).
Finally, the resistive part of the upper MOSFET is given in
Equation 26 as P UP,4 .
? I M ? 2 I L , PP ? ( 1 – d )
P LOW , 1 = r DS ( ON ) ? ? ------ ? ? ( 1 – d ) + -------------------------------------
? I M ?
I P-P
P UP , 4 ≈ r DS ( ON ) ? ? ------ ? ? d + ----------
? N ? 12
(EQ. 21)
? N ? 12
2 2
(EQ. 26)
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 S , and the length of dead times, t d1 and t d2 , at
the beginning and the end of the lower-MOSFET conduction
interval respectively.
The total power dissipated by the upper MOSFET at full load
can now be approximated as the summation of the results
from Equations 23, 24, 25 and 26. Since the power
equations depend on MOSFET parameters, choosing the
correct MOSFETs can be an iterative process involving
repetitive solutions to the loss equations for different
MOSFETs and different switching frequencies.
P LOW , 2 = V D ( ON ) ? f S ? ? ------ + I ----------- ? ? t
? I ?
? I
?
+ ? ------ – ----------- ? ? t d2
M
P-P
2 ? ?
? N
M P-P
? N 2 ?
d1
?
I
(EQ. 22)
Internal Bootstrap Device
All three integrated drivers feature an internal bootstrap
schottky diode. Simply adding an external capacitor across
the BOOT and PHASE pins completes the bootstrap circuit.
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
The bootstrap function is also designed to prevent the
bootstrap capacitor from overcharging due to the large
negative swing at the PHASE node. This reduces voltage
stress on the boot to phase pins.
The bootstrap capacitor must have a maximum voltage
rating above PVCC + 4V and its capacitance value can be
chosen from Equation 27:
C BOOT_CAP ≥ --------------------------------------
Q G1 ? PVCC
Q GATE = ------------------------------------ ? N Q1
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.
Q GATE
Δ V BOOT_CAP
V GS1
(EQ. 27)
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 23,
the required time for this commutation is t 1 and the
approximated associated power loss is P UP,1 .
where Q G1 is the amount of gate charge per upper MOSFET
at V GS1 gate-source voltage and N Q1 is the number of
control MOSFETs. The Δ V BOOT_CAP term is defined as the
allowable droop in the rail of the upper gate drive.
Gate Drive Voltage Versatility
The ISL6323B provides the user flexibility in choosing the
gate drive voltage for efficiency optimization. The controller
I M
I P-P
P UP , 1 ≈ V IN ? ? ------ + ---------- ? ? ? ---- 1 ? ? f S
? N 2 ? ? 2 ?
? t ?
(EQ. 23)
ties the upper and lower drive rails together. Simply applying
a voltage from 5V up to 12V on PVCC sets both gate drive
rail voltages simultaneously.
At turn on, the upper MOSFET begins to conduct and this
transition occurs over a time t 2 . In Equation 24, the
approximate power loss is P UP,2 .
P UP , 2 ≈ V IN ? ? ------ – ---------- ?
? ? ? ? f S
? t 2 ?
? I M I P-P ?
? N 2 ?
----
? 2 ?
26
(EQ. 24)
FN6879.1
May 12, 2010
相关PDF资料 |
PDF描述 |
|---|---|
| RCA18DTMT | CONN EDGECARD 36POS R/A .125 SLD |
| ISL6323ACRZ | IC PWM CTRLR SYNC BUCK DL 48QFN |
| LD6806CX4/25H,315 | IC REG LDO 2.5V .2A 4WLCSP |
| 420USC390MEFCSN30X40 | CAP ALUM 390UF 420V 20% SNAP-IN |
| 2256-19L | POWER CHOKE 33UH MOLDED AXIAL |
相关代理商/技术参数 |
参数描述 |
|---|---|
| ISL6323BCRZR5381 | 制造商:Intersil Corporation 功能描述:4+1 PHASE CONT. FOR CORE+NORTHBRIDGE, 2 PHASE PSI, 3.4MHZ SV - Rail/Tube 制造商:Intersil Corporation 功能描述:IC PWM CTRLR SYNC BUCK DL 48QFN 制造商:Intersil 功能描述:4+1 PHS CONT CORE + NORTHBRDG PROG |
| ISL6323BCRZ-T | 功能描述:IC PWM CTRLR SYNC BUCK DL 48QFN 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 |
| ISL6323BCRZ-TR5381 | 制造商:Intersil Corporation 功能描述:4+1 PHASE CONT. FOR CORE+NORTHBRIDGE, 2 PHASE PSI, 3.4MHZ S - Tape and Reel 制造商:Intersil Corporation 功能描述:IC PWM CTRLR SYNC BUCK DL 48QFN 制造商:Intersil 功能描述:4+1 PHS CONT CORE + NORTHBRDG PROG |
| ISL6323BCRZ-TR5453 | 制造商:Intersil Corporation 功能描述:STD. ISL6323BCRZ-T WITH GOLD BOND WIRE ONLY, T&R - Tape and Reel |
| ISL6323BIRZ | 功能描述:IC PWM CTRLR SYNC BUCK DL 48QFN 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 |
发布紧急采购，3分钟左右您将得到回复。