參數(shù)資料
型號(hào)： ISL6244HRZ
廠商： INTERSIL CORP
元件分類(lèi)： 穩(wěn)壓器
英文描述： Multi-Phase PWM Controller
中文描述： SWITCHING CONTROLLER, 1000 kHz SWITCHING FREQ-MAX, PQCC32
封裝： 5 X 5 MM, LEAD FREE, PLASTIC, MO-220-VHHD, QFN-32
文件頁(yè)數(shù)： 17/25頁(yè)
文件大?。?/td> 845K
代理商： ISL6244HRZ
17
FN9106.3
December 28, 2004
During the soft-start interval, the over-current protection
circuitry remains active. As the output voltage ramps up, if
an over-current condition is detected, the ISL6244
immediately places all PWM signals in a high-impedance
state. The ISL6244 repeats the 2048-cycle wait period and
follows with another soft-start attempt, as shown in
Figure 24. This hiccup mode of operation repeats up to
seven times. On the eighth soft-start attempt, the part
latches off. Once latched off, the ISL6244 can only be reset
when the voltage on EN is brought below 1.23V or VCC is
brought below the POR falling threshold. Upon completion of
a successful soft-start attempt, operation will continue as
normal, PGOOD will return high, and the OC latch counter is
reset.
During VID-on-the-fly transitions, the OC comparator output
is blanked. The quality and mix of output capacitors used in
different applications leads to a wide output capacitance
range. Depending upon the magnitude and direction of the
VID change, the change in voltage across the output
capacitors could result in significant current flow. Summing
this instantaneous current with the load current already
present could drive the average current above the reference
current level and cause an OC trip during the transition. By
blanking the OC comparator during the VID-on-the-fly
transition, nuisance tripping is avoided.
Application Information
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 below. In
addition to this guide, Intersil provides complete reference
designs that include schematics, bills of materials, and
example board layouts for all common microprocessor
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 and the total board space available for power-supply
circuitry. Generally speaking, the most economical solutions
are those where each phase handles between 15 and 20A.
In cases where board space is the limiting constraint, current
can be pushed as high as 30A per phase, but these designs
require heat sinks and forced air to cool the MOSFETs.
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.
LOWER MOSFET POWER CALCULATION
The calculation for heat dissipated in the lower MOSFET is
simple, since virtually all of the heat 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); d is the duty cycle (V
OUT
/V
IN
); and
L is the per-channel inductance.
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.
Thus the total maximum power dissipated in each lower
MOSFET is approximated by the summation of P
L
and P
D
.
0A
0V
5ms/DIV
OUTPUT VOLTAGE,
500mV/DIV
OUTPUT CURRENT, 20A/DIV
FIGURE 24. OVERCURRENT BEHAVIOR IN HICCUP MODE
P
L
r
DS ON
(
)
I
M
N
-----
2
1
d
–
(
)
I
,
-------------12
2
1
d
–
(
)
+
=
(EQ. 14)
P
D
V
D ON
)
f
S
I
M
N
-----
I
---2
+
t
d1
I
M
N
-----
I
---2
–
t
d2
+
=
(EQ. 15)
ISL6244
相關(guān)PDF資料
PDF描述
ISL6244HRZ-T Multi-Phase PWM Controller
ISL6244 Multi-Phase PWM Controller(多相PWM控制器)
ISL6244CRZ Octal D-Type Transparent Latches With 3-State Outputs 20-PDIP -40 to 85
ISL6244CRZ-T Octal D-Type Transparent Latches With 3-State Outputs 20-SO -40 to 85
ISL6244HR Multi-Phase PWM Controller
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
ISL6244HRZ-T 功能描述:電流型 PWM 控制器 VER OF ISL6244HR-T RoHS:否 制造商:Texas Instruments 開(kāi)關(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14
ISL6246C WAF 制造商:Intersil Corporation 功能描述:
ISL6247 6248 WAF 制造商:Intersil Corporation 功能描述:
ISL6247ACR-T 制造商:Rochester Electronics LLC 功能描述:- Tape and Reel 制造商:Intersil Corporation 功能描述:
ISL6247CR 功能描述:IC REG CTRLR PWM 40-QFN RoHS:否 類(lèi)別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:4,000 系列:- PWM 型:電壓模式 輸出數(shù):1 頻率 - 最大:1.5MHz 占空比:66.7% 電源電壓:4.75 V ~ 5.25 V 降壓:是 升壓:無(wú) 回掃:無(wú) 反相:無(wú) 倍增器:無(wú) 除法器:無(wú) Cuk:無(wú) 隔離:無(wú) 工作溫度:-40°C ~ 85°C 封裝/外殼:40-VFQFN 裸露焊盤(pán) 包裝:帶卷 (TR)
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