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參數(shù)資料
| 型號： | ISL9440A |
| 廠商： | Intersil Corporation |
| 英文描述： | Triple, 180∑ Out-of-Phase, Step-Down PWM and Single Linear Controller |
| 中文描述： | 三，180Σ門診的階段，降壓型PWM和線性控制器單 |
| 文件頁數(shù)： | 13/20頁 |
| 文件大小： | 978K |
| 代理商： | ISL9440A |
13
FN6383.1
December 5, 2007
ISL9440, ISL9440A, ISL9441
Functional Description
General Description
The ISL9440, ISL9440A and ISL9441 integrate control
circuits for three synchronous buck converters and one
linear controller. The three synchronous bucks operate out of
phase to substantially reduce the input ripple and thus
reduce the input filter requirements. The chip has 3 control
lines (EN1, EN2 and EN3), which provide independent
control for each of the synchronous buck outputs.
The buck PWM controllers employ free-running frequency of
300kHz (ISL9440 and ISL9441) and 600kHz (ISL9440A).
The current mode control scheme with an input voltage feed-
forward ramp input to the modulator provides an excellent
rejection of input voltage variations and provides simplified
loop compensations.
The linear controller can drive either a PNP or PFET to provide
ultra low-dropout regulation with programmable voltages.
Internal 5V Linear Regulator (VCC_5V)
All ISL9440, ISL9440A and ISL9441 functions are internally
powered from an on-chip, low dropout 5V regulator. The
maximum regulator input voltage is 24V. Bypass the
regulator’s output (VCC_5V) with a 4.7μF capacitor to
ground. The dropout voltage for this LDO is typically 600mV,
so when VIN is greater than 5.6V, VCC_5V is typically 5V.
The ISL9440, ISL9440A and ISL9441 also employ an
undervoltage lockout circuit that disables both regulators
when VCC_5V falls below 4.4V.
The internal LDO can source over 60mA to supply the IC,
power the low side gate drivers and charge the external boot
capacitor. When driving large FETs especially at 300kHz
(ISL9440, ISL9441)/600kHz (ISL9440A) frequency, little or
no regulator current may be available for external loads.
For example, a single large FET with 15nC total gate charge
requires 15nC x 300kHz = 4.5mA (15nC x 600kHz = 9mA).
Also, at higher input voltages with larger FETs, the power
dissipation across the internal 5V will increase. Excessive
dissipation across this regulator must be avoided to prevent
junction temperature rise. Larger FETs can be used with 5V
±10% input applications. The thermal overload protection
circuit will be triggered, if the VCC_5V output is short-circuit.
Connect VCC_5V to V
IN
for 5V ±10% input applications.
Digital Enable Signals
The typical applications for the ISL9440, ISL9440A and
ISL9441 are using digital sequencing controllers for the
power rails. Using a digital enable rather than an analog soft-
start provides a well controlled method for sequencing up
and down on the power rails.
Soft-Start Operation
The ISL9440, ISL9440A and ISL9441 have a fixed soft-start
time, 1.7ms (TYP). PGOOD will not toggle to high until soft-
start is done and all the four outputs are up and in
regulations.
Output Voltage Programming
The ISL9440, ISL9440A and ISL9441 use a precision
internal reference voltage to set the output voltage. Based
on this internal reference, the output voltage can thus be set
from 0.8V up to a level determined by the input voltage, the
maximum duty cycle, and the conversion efficiency of the
circuit.
A resistive divider from the output to ground sets the output
voltage of either PWM channel. The center point of the
divider shall be connected to FBx pin. The output voltage
value is determined by Equation 1.
0.8VR1
R2
where R1 is the top resistor of the feedback divider network
and R2 is the resistor connected from FBx to ground.
Out-of-Phase Operation
To reduce input ripple current, Channel 1 and Channel 2
operate 180° out-of-phase, Channel 3 keeps 0 phase degree
with Channel 1. Channel 1 and Channel 2 typically output
higher load compared to Channel 3 because of their stronger
drivers. This reduces the input capacitor ripple current
requirements, reduces power supply-induced noise, and
improves EMI. This effectively helps to lower component cost,
save board space and reduce EMI.
Triple PWMs typically operate in-phase and turn on both upper
FETs at the same time. The input capacitor must then support
the instantaneous current requirements of the three switching
regulators simultaneously, resulting in increased ripple voltage
and current. The higher RMS ripple current lowers the
efficiency due to the power loss associated with the ESR of the
input capacitor. This typically requires more low-ESR capacitors
in parallel to minimize the input voltage ripple and ESR-related
losses, or to meet the required ripple current rating.
With synchronized out-of-phase operation, the high-side
MOSFETs turn on 180° out-of-phase. The instantaneous input
current peaks of both regulators no longer overlap, resulting in
reduced RMS ripple current and input voltage ripple. This
reduces the required input capacitor ripple current rating,
allowing fewer or less expensive capacitors, and reducing the
shielding requirements for EMI. The typical operating curves
show the synchronized 180° out-of-phase operation.
Input Voltage Range
The ISL9440, ISL9440A and ISL9441 are designed to
operate from input supplies ranging from 4.5V to 24V.
For 5V ±10% input applications, ISL9441 is suggested. The
reason is that VIN and VCC_5V Pin should be tied together
for this input application. The early warning function will pull
PGOOD and RST low for ISL9440 and ISL9440A. ISL9441
has not been implemented with early warning function.
V
OUTx
R2
+
=
(EQ. 1)
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| ISL9440AEVAL1Z | 功能描述:EVALUATION BOARD FOR ISL9440 RoHS:是 類別:編程器，開發(fā)系統(tǒng) >> 評估板 - DC/DC 與 AC/DC（離線）SMPS 系列:- 產品培訓模塊:Obsolescence Mitigation Program 標準包裝:1 系列:True Shutdown™ 主要目的:DC/DC，步升 輸出及類型:1，非隔離 功率 - 輸出:- 輸出電壓:- 電流 - 輸出:1A 輸入電壓:2.5 V ~ 5.5 V 穩(wěn)壓器拓撲結構:升壓 頻率 - 開關:3MHz 板類型:完全填充 已供物品:板 已用 IC / 零件:MAX8969 |
| ISL9440AIRZ | 功能描述:IC REG QD BCK/LINEAR SYNC 32-QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 線性 + 切換式 系列:- 標準包裝:2,500 系列:- 拓撲:降壓（降壓）同步（3），線性（LDO）（2） 功能:任何功能 輸出數(shù):5 頻率 - 開關:300kHz 電壓/電流 - 輸出 1:控制器 電壓/電流 - 輸出 2:控制器 電壓/電流 - 輸出 3:控制器 帶 LED 驅動器:無 帶監(jiān)控器:無 帶序列發(fā)生器:是 電源電壓:5.6 V ~ 24 V 工作溫度:-40°C ~ 85°C 安裝類型:* 封裝/外殼:* 供應商設備封裝:* 包裝:* |
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| ISL9440BEVAL1Z | 功能描述:EVAL BOARD 1 FOR ISL9440B RoHS:是 類別:編程器，開發(fā)系統(tǒng) >> 評估板 - DC/DC 與 AC/DC（離線）SMPS 系列:* 產品培訓模塊:Obsolescence Mitigation Program 標準包裝:1 系列:True Shutdown™ 主要目的:DC/DC，步升 輸出及類型:1，非隔離 功率 - 輸出:- 輸出電壓:- 電流 - 輸出:1A 輸入電壓:2.5 V ~ 5.5 V 穩(wěn)壓器拓撲結構:升壓 頻率 - 開關:3MHz 板類型:完全填充 已供物品:板 已用 IC / 零件:MAX8969 |
| ISL9440BIRZ | 功能描述:IC REG QD BCK/LINEAR SYNC 32-QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 線性 + 切換式 系列:- 標準包裝:2,500 系列:- 拓撲:降壓（降壓）同步（2），線性（LDO）（1） 功能:任何功能 輸出數(shù):3 頻率 - 開關:300kHz 電壓/電流 - 輸出 1:控制器 電壓/電流 - 輸出 2:控制器 電壓/電流 - 輸出 3:控制器 帶 LED 驅動器:無 帶監(jiān)控器:無 帶序列發(fā)生器:是 電源電壓:4.5 V ~ 24 V 工作溫度:-40°C ~ 85°C 安裝類型:* 封裝/外殼:28-TSSOP（0.173"，4.40mm 寬） 供應商設備封裝:* 包裝:帶卷 (TR) 其它名稱:ISL6402IVZ-TTR |
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