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参数资料
| 型号： | ISL6341IRZ |
| 厂商： | Intersil |
| 文件页数： | 16/17页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM VM 10-TDFN |
| 标准包装： | 100 |
| PWM 型： | 电压模式 |
| 输出数： | 1 |
| 频率 - 最大： | 330kHz |
| 占空比： | 85% |
| 电源电压： | 4.5 V ~ 14.4 V |
| 降压： | 是 |
| 升压： | 无 |
| 回扫： | 无 |
| 反相： | 无 |
| 倍增器： | 无 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 无 |
| 工作温度： | -40°C ~ 85°C |
| 封装/外壳： | 10-WFDFN 裸露焊盘 |
| 包装： | 管件 |
ISL6341, ISL6341A, ISL6341B, ISL6341C
For a through-hole design, several electrolytic capacitors may
be needed. For surface mount designs, solid tantalum
capacitors can also be used, but caution must be exercised
with regard to the capacitor surge current rating. These
capacitors must be capable of handling the surge current at
power-up. Some capacitor series available from reputable
manufacturers are surge current tested.
MOSFET Selection/Considerations
The ISL6341x requires 2 N-Channel power MOSFETs. These
should be selected based upon r DS(ON) , gate supply
requirements, and thermal management requirements.
In high-current applications, the MOSFET power dissipation,
package selection and heatsink are the dominant design
factors. The power dissipation includes two loss components;
conduction loss and switching loss. The conduction losses are
the largest component of power dissipation for both the upper
and the lower MOSFETs. These losses are distributed between
the two MOSFETs according to duty factor. The switching
losses seen when sourcing current will be different from the
switching losses seen when sinking current. When sourcing
current, the upper MOSFET realizes most of the switching
losses. The lower switch realizes most of the switching losses
when the converter is sinking current (see Equation 12).
Equation 12 assumes linear voltage-current transitions and
does not adequately model power loss due to the reverse-
recovery of the upper and lower MOSFET’s body diode. The
gate-charge losses are dissipated by the ISL6341x and don't
heat the MOSFETs. However, large gate-charge increases the
switching interval, t SW which increases the MOSFET switching
losses. Ensure that both MOSFETs are within their maximum
junction temperature at high ambient temperature by
calculating the temperature rise according to package
For 5V only operation, given the reduced available gate bias
voltage (5V), logic-level transistors should be used for both
N-MOSFETs. Look for r DS(ON) ratings at 4.5V. Caution
should be exercised with devices exhibiting very low
V GS(ON) characteristics. The shoot-through protection
present aboard the ISL6341x may be circumvented by these
MOSFETs if they have large parasitic impedences 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. Also avoid MOSFETs
with excessive switching times; the circuitry is expecting
transitions to occur in under 50ns or so.
BOOTSTRAP Considerations
Figure 15 shows the upper gate drive (BOOT pin) supplied
by a bootstrap circuit from V GD . For convenience, V GD
usually shares the V IN or V CC supply; it can be any voltage
in the 5V to 12V range. The boot capacitor, C BOOT ,
develops a floating supply voltage referenced to the PHASE
pin. The supply is refreshed to a voltage of V GD less the
boot diode drop (V D ) each time the lower MOSFET, Q 2 ,
turns on. Check that the voltage rating of the capacitor is
above the maximum V CC voltage in the system; a 16V rating
should be sufficient for a 12V system. A value of 0.1μF is
typical for many systems driving single MOSFETs.
If V CC is 12V, but V IN is lower (such as 5V), then another
option is to connect the BOOT pin to 12V, and remove the
BOOT cap (although, you may want to add a local capacitor
from BOOT to GND). This will make the UGATE V GS voltage
equal to (12V - 5V = 7V). That should be high enough to
drive most MOSFETs, and low enough to improve the
efficiency slightly. This also saves a boot diode and
capacitor.
thermal-resistance specifications. A separate heatsink may be
+V CC
+V GD
+V IN
necessary depending upon MOSFET power, package type,
ambient temperature and air flow.
VCC
P UPPER = Io × r DS ( ON ) × D + --- ? Io × V IN × t SW × F S
Losses while Sourcing Current
2 1
2
P LOWER = Io 2 x r DS(ON) x (1 - D)
Losses while Sinking Current
ISL6341x
BOOT
UGATE
PHASE
C BOOT
Q1
V G-S ≈ V GD - V D
P UPPER = Io 2 x r DS(ON) x D
P LOWER = Io × r DS ( ON ) × ( 1 – D ) + --- ? Io × V IN × t SW × F S
(EQ. 12)
2 1
2
Where: D is the duty cycle = V OUT / V IN ,
t SW is the combined switch ON and OFF time, and
-
+
VCC
LGATE/OCSET
Q2
V G-S ≈ V CC
f SW is the switching frequency.
When operating with a 12V power supply for V CC (or down
to a minimum supply voltage of 4.5V), a wide variety of
N-MOSFETs can be used. Check the absolute maximum
V GS rating for both MOSFETs; it needs to be above the
highest V CC voltage allowed in the system; that usually
means a 20V V GS rating (which typically correlates with a
30V V DS maximum rating). Low threshold transistors
(around 1V or below) are not recommended, as explained in
the following.
16
GND
FIGURE 15. UPPER GATE DRIVE BOOTSTRAP
FN6538.2
December 2, 2008
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相关代理商/技术参数 |
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|---|---|
| ISL6341IRZ-T | 功能描述:IC REG CTRLR BUCK PWM VM 10-TDFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:275kHz 占空比:50% 电源电压:18 V ~ 110 V 降压:无 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:是 工作温度:-40°C ~ 85°C 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) |
| ISL6353CRTZ | 功能描述:电流型 PWM 控制器 VR12 MEMORY CNTRLR 3 PHS 2 INT 5V DRVRS RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| ISL6353CRTZ-T | 功能描述:电流型 PWM 控制器 VR12 MEMORY CNTRLR 3 PHS 2 INT 5V DRVRS RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| ISL6353CRTZ-TS2568 | 制造商:Intersil Corporation 功能描述:INTEL, ISL6353CRTZ-T W/BARCODE LABELS, 12 MONTH D/C RESTRICT - Tape and Reel |
| ISL6353CRZ | 制造商:Intersil 功能描述:Multiphase PWM Regulator for VR12 DDR Memory Systems |
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