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| 型号： | ISL6527AIB-T |
| 厂商： | Intersil |
| 文件页数： | 12/16页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BST PWM VM 14-SOIC |
| 标准包装： | 2,500 |
| PWM 型： | 电压模式 |
| 输出数： | 1 |
| 频率 - 最大： | 650kHz |
| 占空比： | 100% |
| 电源电压： | 2.97 V ~ 3.63 V |
| 降压： | 是 |
| 升压： | 是 |
| 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： | 14-SOIC（0.154"，3.90mm 宽） |
| 包装： | 带卷 (TR) |
ISL6527, ISL6527A
approximate response time interval for application and
removal of a transient load:
factors. The power dissipation includes two loss components;
conduction loss and switching loss. The conduction losses are
t RISE =
L x I TRAN
V IN - V OUT
(EQ. 14)
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
t FALL =
L x I TRAN
V OUT
(EQ. 15)
from the switching losses seen when sinking current. When
sourcing current, the upper MOSFET realizes most of the
P UPPER = Io × r DS ( ON ) × D + --- ? Io × V IN × t SW × f s
where: I TRAN is the transient load current step, t RISE is the
response time to the application of load, and t FALL is the
response time to the removal of load. The worst case
response time can be either at the application or removal of
load. Be sure to check both Equations 14 and 15 at the
minimum and maximum output levels for the worst case
response time.
Input Capacitor Selection
Use a mix of input bypass capacitors to control the voltage
overshoot across the MOSFETs. Use small ceramic
capacitors for high frequency decoupling and bulk capacitors
to supply the current needed each time Q 1 turns on. Place the
small ceramic capacitors physically close to the MOSFETs
and between the drain of Q 1 and the source of Q 2 .
The important parameters for the bulk input capacitor are the
voltage rating and the RMS current rating. For reliable
operation, select the bulk capacitor with voltage and current
switching losses. The lower switch realizes most of the
switching losses when the converter is sinking current
(see Equations 17 and 18). These equations assume linear
voltage-current transitions and do not adequately model
power loss due the reverse-recovery of the upper and lower
MOSFET’s body diode. The gate-charge losses are
dissipated by the ISL6527, ISL6527A 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
thermal-resistance specifications. A separate heatsink may be
necessary depending upon MOSFET power, package type,
ambient temperature and air flow.
Losses while Sourcing current
2 1
2
ratings above the maximum input voltage and largest RMS
current required by the circuit. The capacitor voltage rating
P LOWER = Io 2 x r DS(ON) x (1 - D)
(EQ. 17)
P LOWER = Io × r DS ( ON ) × ( 1 – D ) + --- ? Io × V IN × t SW × f s
should be at least 1.25x greater than the maximum input
voltage and a voltage rating of 1.5x is a conservative
guideline. The RMS current rating requirement for the input
capacitor of a buck regulator is approximately 1/2 the DC load
current.
The maximum RMS current required by the regulator may be
closely approximated through Equation 16:
Losses while Sinking current
P UPPER = Io 2 x r DS(ON) x D
2 1
2
(EQ. 18)
where: D is the duty cycle = V OUT /V IN , t SW is the combined
switch ON- and OFF-time, and f S is the switching frequency.
---------------- × ? I OUT
1 ? V IN – V OUT V OUT ? 2 ?
L × f s
? V IN ? ?
I RMS
MAX
=
V OUT ?
V IN ?
MAX
2
+ ------ × ? -------------------------------- × ---------------- ? ?
12
Given the reduced available gate bias voltage (5V), logic-level
or sub-logic-level transistors should be used for both
(EQ. 16)
For a through-hole design, several electrolytic capacitors may
be needed. For surface mount designs, solid tantalum
capacitors can 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 ISL6527, ISL6527A require two 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
12
N-MOSFETs. Caution should be exercised with devices
exhibiting very low V GS(ON) characteristics. The shoot-through
protection present aboard the ISL6527, ISL6527A 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 7. The boot
capacitor, C BOOT , develops a floating supply voltage
referenced to the PHASE pin. This supply is refreshed each
cycle, when D BOOT conducts, to a voltage of CPVOUT less the
boot diode drop, V D , plus the voltage rise across Q LOWER .
FN9056.10
November 18, 2008
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相关代理商/技术参数 |
参数描述 |
|---|---|
| ISL6527AIBZ | 制造商:Rochester Electronics LLC 功能描述: 制造商:Intersil Corporation 功能描述: |
| ISL6527AIR | 功能描述:IC REG CTRLR BST PWM VM 16-QFN RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,000 系列:- PWM 型:电压模式 输出数:1 频率 - 最大:1.5MHz 占空比:66.7% 电源电压:4.75 V ~ 5.25 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:40-VFQFN 裸露焊盘 包装:带卷 (TR) |
| ISL6527AIR-T | 功能描述:IC REG CTRLR BST PWM VM 16-QFN RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,000 系列:- PWM 型:电压模式 输出数:1 频率 - 最大:1.5MHz 占空比:66.7% 电源电压:4.75 V ~ 5.25 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:40-VFQFN 裸露焊盘 包装:带卷 (TR) |
| ISL6527AIRZ | 功能描述:电压模式 PWM 控制器 600KHZ SNG PWM CONTR LR W/EXT. REF. 16LD RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel |
| ISL6527AIRZ-T | 功能描述:IC REG CTRLR BST PWM VM 16-QFN 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) |
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