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參數(shù)資料
| 型號： | ISL6406IV |
| 廠商： | INTERSIL CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Quadruple 2-Input Positive-NAND Gates 14-SO -40 to 85 |
| 中文描述： | SWITCHING CONTROLLER, 770 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封裝： | PLASTIC, MO-153-AB, TSSOP-16 |
| 文件頁數(shù)： | 6/18頁 |
| 文件大小： | 380K |
| 代理商： | ISL6406IV |
14
FN9073.7
January 16, 2007
Given the reduced available gate bias voltage (5V), logic-
level or sub-logic-level transistors should be used for both
N-MOSFETs. Caution should be exercised with devices
exhibiting very low VGS(ON) characteristics. The shoot-
through protection present aboard the ISL6406 may be
circumvented by these MOSFETs if they have large parasitic
impedances and/or capacitances that would inhibit the gate
of the MOSFET from being discharged below its threshold
level before the complementary MOSFET is turned on.
Bootstrap Component Selection
External bootstrap components, a diode and capacitor, are
required to provide sufficient gate enhancement to the upper
MOSFET. The internal MOSFET gate driver is supplied by
the external bootstrap circuitry as shown in Figure 9. The
boot capacitor, CBOOT, develops a floating supply voltage
referenced to the PHASE pin. This supply is refreshed each
cycle, when DBOOT conducts, to a voltage of CPVOUT less
the boot diode drop, VD, plus the voltage rise across
QLOWER.
Just after the PWM switching cycle begins and the charge
transfer from the bootstrap capacitor to the gate capacitance
is complete, the voltage on the bootstrap capacitor is at its
lowest point during the switching cycle. The charge lost on
the bootstrap capacitor will be equal to the charge
transferred to the equivalent gate-source capacitance of the
upper MOSFET as shown:
where QGATE is the maximum total gate charge of the upper
MOSFET, CBOOT is the bootstrap capacitance, VBOOT1 is
the bootstrap voltage immediately before turn-on, and
VBOOT2 is the bootstrap voltage immediately after turn-on.
The bootstrap capacitor begins its refresh cycle when the gate
drive begins to turn-off the upper MOSFET. A refresh cycle
ends when the upper MOSFET is turned on again, which
varies depending on the switching frequency and duty cycle.
The minimum bootstrap capacitance can be calculated by
Typical gate charge values for MOSFETs considered in
these types of applications range from 20nC to 100nC.
Since the voltage drop across QLOWER is negligible,
VBOOT1 is simply VCPVOUT - VD. A schottky diode is
recommended to minimize the voltage drop across the
bootstrap capacitor during the on-time of the upper
MOSFET. Initial calculations with VBOOT2 no less than 4V
will quickly help narrow the bootstrap capacitor range.
For example, consider an upper MOSFET is chosen with a
maximum gate charge, Qg, of 100nC. Limiting the voltage
drop across the bootstrap capacitor to 1V results in a value
of no less than 0.1
μF. The tolerance of the ceramic capacitor
should also be considered when selecting the final bootstrap
capacitance value.
A fast recovery diode is recommended when selecting a
bootstrap diode to reduce the impact of reverse recovery
charge loss. Otherwise, the recovery charge, QRR, would
have to be added to the gate charge of the MOSFET and
taken into consideration when calculating the minimum
bootstrap capacitance.
ISL6406
GND
LGATE
UGATE
PHASE
BOOT
VIN
NOTE:
VG-S = VCC
CBOOT
DBOOT
QUPPER
QLOWER
+
-
FIGURE 9. UPPER GATE DRIVE BOOTSTRAP
VG-S = VCC -VD
+
VD
-
CPVOUT
Q
GATE
C
BOOT
V
BOOT1
V
BOOT2
–
()
×
=
(EQ. 13)
C
BOOT
Q
GATE
V
BOOT1
V
–
BOOT2
-----------------------------------------------------
=
(EQ. 14)
ISL6406
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| ISL6406IV-T | 功能描述:IC REG CTRLR BUCK PWM VM 16TSSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標準包裝: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 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 85°C 封裝/外殼:40-VFQFN 裸露焊盤 包裝:帶卷 (TR) |
| ISL6406IVZ | 功能描述:電壓模式 PWM 控制器 VER OF ISL6406IV RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓撲結(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開關(guān)頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel |
| ISL6406IVZ-T | 功能描述:電壓模式 PWM 控制器 VER OF ISL6406IV-T RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓撲結(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開關(guān)頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel |
| ISL6406MREPZ | 制造商:Intersil Corporation 功能描述:V62/08610-01XE, -55 TO 125C PB-FREE VID VERSION OF THE ISL64 - Rail/Tube |
| ISL6406MREPZ-TK | 制造商:Intersil Corporation 功能描述:V62/08610-01XE, -55 TO 125C PB-FREE VID VERSION OF THE ISL64 - Tape and Reel |
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