參數(shù)資料
型號(hào)： ISL6420AIAZ
廠商： INTERSIL CORP
元件分類： 穩(wěn)壓器
英文描述： Advanced Single Synchronous Buck Pulse-Width Modulation (PWM) Controller
中文描述： 0.05 A SWITCHING CONTROLLER, 1400 kHz SWITCHING FREQ-MAX, PDSO20
封裝： 0.150 INCH, GREEN, PLASTIC, QSOP-20
文件頁(yè)數(shù)： 14/20頁(yè)
文件大?。?/td> 560K
代理商： ISL6420AIAZ
14
FN9169.1
October 13, 2005
Undervoltage
If the voltage on the FB pin is less than 15% of the reference
voltage for 8 consecutive PWM cycles, then the circuit enters
into soft-start hiccup mode. This mode is identical to the
overcurrent hiccup mode.
Overvoltage Protection
If the voltage on the FB pin exceeds the reference voltage by
15%, the lower gate driver is turned on continuously to
discharge the output voltage. If the overvoltage condition
continues for 32 consecutive PWM cycles, then the chip is
turned off with the gate drivers three-stated. The voltage on
the FB pin will fall and reach the 15% undervoltage
threshold. After 8 clock cycles, the chip will enter soft-start
hiccup mode. This mode is identical to the overcurrent
hiccup mode.
Gate Control Logic
The gate control logic translates generated PWM control
signals into the MOSFET gate drive signals providing
necessary amplification, level shifting and shoot-through
protection. Also, it has functions that help optimize the IC
performance over a wide range of operational conditions.
Since MOSFET switching time can vary dramatically from
type to type and with the input voltage, the gate control logic
provides adaptive dead time by monitoring the gate-to-
source voltages of both upper and lower MOSFETs. The
lower MOSFET is not turned on until the gate-to-source
voltage of the upper MOSFET has decreased to less than
approximately 1V. Similarly, the upper MOSFET is not turned
on until the gate-to-source voltage of the lower MOSFET has
decreased to less than approximately 1V. This allows a wide
variety of upper and lower MOSFETs to be used without a
concern for simultaneous conduction, or shoot-through.
Startup into Pre-Biased Load
The ISL6420A is designed to power up into a pre-biased
load. This is achieved by transitioning from Diode Emulation
mode to a Forced Continuous Conduction mode during
startup. The lower gate turns ON for a short period of time
and the voltage on the phase pin is sensed. When this goes
negative the lower gate is turned OFF and remains OFF till
the next cycle. As a result the inductor current will not go
negative during soft-start and thus will not discharge the pre-
biased load. The waveform for this condition is shown below.
Application Guidelines
Layout Considerations
As in any high frequency switching converter, layout is very
important. Switching current from one power device to
another can generate voltage transients across the
impedances of the interconnecting bond wires and circuit
traces. These interconnecting impedances should be
minimized by using wide, short printed circuit traces. The
critical components should be located as close together as
possible using ground plane construction or single point
grounding.
FIGURE 13. PREBIASED OUTPUT AT 25mA LOAD
V
IN
= 12V, V
OUT
= 3.3V at 25mA LOAD
GND
L
O
C
O
LGATE
UGATE
PHASE
Q1
Q2
D2
FIGURE 14. PRINTED CIRCUIT BOARD POWER AND
GROUND PLANES OR ISLANDS
V
IN
V
OUT
RETURN
ISL6420A
C
IN
L
ISL6420A
相關(guān)PDF資料
PDF描述
ISL6420AIRZ Advanced Single Synchronous Buck Pulse-Width Modulation (PWM) Controller
ISL6420AIRZ-TK Advanced Single Synchronous Buck Pulse-Width Modulation (PWM) Controller
ISL6420A Advanced Single Synchronous Buck Pulse-Width Modulation (PWM) Controller(單片同步降壓脈寬調(diào)制控制器)
ISL6420AIAZ-TK Circular Connector; No. of Contacts:22; Series:MS27473; Body Material:Aluminum; Connecting Termination:Crimp; Connector Shell Size:12; Circular Contact Gender:Socket; Circular Shell Style:Straight Plug; Insert Arrangement:12-35 RoHS Compliant: No
ISL6420IAZ-TK PCB Relay; Contacts:SPDT; Contact Carry Current:500mA; Coil Voltage DC Max:9V; Relay Terminals:SMT Gullwing; Coil Resistance:405ohm; Contact Rating:10mA at 30VAC; Leaded Process Compatible:Yes; Peak Reflow Compatible (260 C):No RoHS Compliant: Yes
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
ISL6420AIAZS2698 制造商:Intersil Corporation 功能描述:PB-FREE SYNC BUCK PWM CONT. W/ 4.5V-28V INPUT,20LD QSOP - Rail/Tube 制造商:Rochester Electronics LLC 功能描述:
ISL6420AIAZ-TK 功能描述:IC REG CTRLR BUCK PWM VM 20-QSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,500 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:275kHz 占空比:50% 電源電壓:18 V ~ 110 V 降壓:無(wú) 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:是 工作溫度:-40°C ~ 85°C 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 包裝:帶卷 (TR)
ISL6420AIAZ-TKS2698 制造商:Intersil Corporation 功能描述:PB-FREE SYNC BUCK PWM CONT. W/ 4.5V-28V INPUT,20LD QSOP, T&R - Tape and Reel
ISL6420AIR 制造商:Intersil Corporation 功能描述:VOLT MODE PWM CNTRLR 0.6V TO 27.5V 700MA 20QFN - Rail/Tube
ISL6420AIR-TK 功能描述:IC REG CTRLR BUCK PWM VM 20-QFN RoHS:否 類別: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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