- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄384529 > ISL88550AIRZ-T (INTERSIL CORP) Synchronous Step Down Controller with Sourcing and Sinking LDO Regulator PDF資料下載
參數(shù)資料
| 型號(hào)： | ISL88550AIRZ-T |
| 廠商： | INTERSIL CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Synchronous Step Down Controller with Sourcing and Sinking LDO Regulator |
| 中文描述： | SWITCHING CONTROLLER, 600 kHz SWITCHING FREQ-MAX, PQCC28 |
| 封裝： | 5 X 5 MM, ROHS COMPLIANT, PLASTIC, MO-220WHHD-1, TQFN-28 |
| 文件頁(yè)數(shù)： | 21/25頁(yè) |
| 文件大小： | 928K |
| 代理商： | ISL88550AIRZ-T |
第1頁(yè)第2頁(yè)第3頁(yè)第4頁(yè)第5頁(yè)第6頁(yè)第7頁(yè)第8頁(yè)第9頁(yè)第10頁(yè)第11頁(yè)第12頁(yè)第13頁(yè)第14頁(yè)第15頁(yè)第16頁(yè)第17頁(yè)第18頁(yè)第19頁(yè)第20頁(yè)當(dāng)前第21頁(yè)第22頁(yè)第23頁(yè)第24頁(yè)第25頁(yè)
21
FN6168.0
October 12, 2005
ILIM connected to the center tap. The external 250mV to 2V
adjustment range corresponds to a 25mV to 200mV valley
current-limit threshold. When adjusting the current limit, use
1% tolerance resistors and a divider current of approximately
10μA to prevent significant inaccuracy in the valley current-
limit tolerance.
Setting the Foldback Current Limit (Buck)
Alternately, foldback current limit can be implemented if UVP
is disabled. Foldback current limit reduces the power
dissipation of external components so they can withstand
indefinite output overload or short circuit. With automatic
recovery after the fault condition is removed. To implement
foldback current limit, connect a resistor from V
OUT
to ILIM
(R1 in the typical application circuit), in addition to the
resistor-divider network (R4 and R5) used for setting the
adjustable current limit.
The following is a procedure for calculating the values of R1,
R4, and R5:
1. Calculate the voltage, V
ILIM
:
2. Pick a percentage of foldback, P
FB
, from 15% to 40%.
3. Calculate the voltage,V
VILIM(0V)
, when the output is
shorted (0V).
FIGURE 27. FOLDBACK CURRENT LIMIT
4. The value of R4 can be calculated as:
5. The parallel combination of R1 and R5 is calculated as:
6. Then R5 can be calculated as:
7. Then R1 is calculated as:
Boost-Supply Capacitor Selection (Buck)
The boost capacitor should be 0.1μF to 4.7μF, depending on
the input and output voltages, external components, and PC
board layout. The boost capacitance should be as large as
possible to prevent it from charging to excessive voltage, but
small enough to adequately charge during the minimum low-
side MOSFET conduction time, which happens at maximum
operating duty cycle (this occurs at minimum input voltage).
In addition, ensure that the boost capacitor does not
discharge to below the minimum gate-to-source voltage
required to keep the high-side MOSFET fully enhanced for
lowest on-resistance. This minimum gate to source voltage
(V
GS(MIN)
) is determined by:
where V
DD
is 5V, Q
G
is the total gate charge of the high-side
MOSFET, and C
BOOST
is the boost capacitor value where
C
BOOST
is C7 in the typical application circuit.
Transient Response (Buck)
The inductor ripple current also affects transient response
performance, especially at low V
IN
- V
OUT
differentials. Low
inductor values allow the inductor current to slew faster,
replenishing charge removed from the output filter capacitors
by a sudden load step. The output sag is also a function of
the maximum duty factor, which can be calculated from the
on-time and minimum off-time:
where t
OFF(MIN)
is the minimum off-time (see the Electrical
Characteristics) and K is from Table 1.
The overshoot during a full-load to no-load transient due to
stored inductor energy can be calculated as:
)
2
Q
(
DSON
)
MAX
(
LOAD
I
ILIM
V
R
2
LIR
1
10
×
×
×
=
VDDQ
REF
ILIM
ISL88551A
R4
R5
C
REF
GND
R1
ISL88550A/
ILIM
V
FB
)
V
0
(
ILIM
V
P
×
=
A
10
V
V
2
4
R
)
V
0
(
ILIM
μ
=
4
R
A
10
V
μ
2
R
5
R
//
1
R
=
(
)
(
)
(
)
[
]
5
R
//
1
R
)
V
0
(
ILIM
V
ILIM
V
)
V
0
(
ILIM
V
ILIM
V
5
R
//
1
R
R
4
R
VDDQ
R
4
R
VDDQ
5
R
×
×
×
×
=
[
]
5
R
//
1
R
5
R
//
1
R
R
5
R
R
5
R
1
R
×
=
(
)
BOOST
G
DD
MIN
GS
C
Q
V
V
×
=
(
)
(
)
(
)
(
)
+
×
×
+
×
×
=
MIN
OFF
IN
OUT
V
IN
OUT
V
OUT
MIN
OFF
IN
OUT
V
2
MAX
LOAD
I
SAG
V
t
K
V
V
C
2
t
K
V
L
(
)
V
OUT
OUT
2
MAX
LOAD
C
×
SOAR
V
2
L
I
×
×
=
ISL88550A
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| ISL88694 | Octal Transparent D-Type Latches With 3-State Outputs 20-SOIC -40 to 85 |
| ISL88694IH5 | SMBus Accelerator (SMA) |
| ISL88694IH5-TK | SMBus Accelerator (SMA) |
| ISL88694IH5Z | SMBus Accelerator (SMA) |
| ISL88694IH5Z-TK | SMBus Accelerator (SMA) |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ISL88550AIRZ-T7 | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 Integrated DDR Power Controller, 28LD 5x5 TQFN Pb-free, 1K O RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT |
| ISL88550AIRZ-TR5339 | 制造商:Intersil Corporation 功能描述:SCM ASSY.INTEGRATED DDR POWER CONTROLLER, 28LD 5X5 TQFN PB-F - Tape and Reel 制造商:Intersil Corporation 功能描述:IC SYNCH STEP DOWN CONT 28TQFN 制造商:Intersil 功能描述:SCM ASSY INTEGRTD DDR PWR CNTRLR |
| ISL88550AIRZ-TS2715 | 制造商:Intersil Corporation 功能描述:BROADCOM, ISL88550AIRZ-T W/BUSINESS TRACKING REQUIREMENTS, S - Tape and Reel |
| ISL88694EVAL | 功能描述:EVALUATION BOARD ISL88694 RoHS:否 類別:編程器，開發(fā)系統(tǒng) >> 評(píng)估演示板和套件 系列:- 標(biāo)準(zhǔn)包裝:1 系列:PCI Express® (PCIe) 主要目的:接口，收發(fā)器，PCI Express 嵌入式:- 已用 IC / 零件:DS80PCI800 主要屬性:- 次要屬性:- 已供物品:板 |
| ISL88694IH5 | 功能描述:IC ACCELERATOR SMBUS SOT-5 RoHS:否 類別:集成電路 (IC) >> 接口 - 信號(hào)緩沖器，中繼器，分配器 系列:- 標(biāo)準(zhǔn)包裝:160 系列:- 類型:轉(zhuǎn)發(fā)器 Tx/Rx類型:以太網(wǎng) 延遲時(shí)間:- 電容 - 輸入:- 電源電壓:2.37 V ~ 2.63 V 電流 - 電源:60mA 安裝類型:表面貼裝 封裝/外殼:64-TQFP 裸露焊盤 供應(yīng)商設(shè)備封裝:64-TQFP-EP（10x10） 包裝:托盤 其它名稱:Q5134101 |
發(fā)布緊急采購(gòu)，3分鐘左右您將得到回復(fù)。