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| 型号： | ISL6612BIRZ |
| 厂商： | Intersil |
| 文件页数： | 8/12页 |
| 文件大小： | 0K |
| 描述： | IC MOSFET DRVR SYNC BUCK 10-DFN |
| 标准包装： | 100 |
| 配置： | 高端和低端，同步 |
| 输入类型： | PWM |
| 延迟时间： | 10ns |
| 电流 - 峰： | 1.25A |
| 配置数： | 1 |
| 输出数： | 2 |
| 高端电压 - 最大（自引导启动）： | 36V |
| 电源电压： | 7 V ~ 13.2 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 10-VFDFN 裸露焊盘 |
| 供应商设备封装： | 10-DFN（3x3） |
| 包装： | 管件 |
ISL6612B, ISL6613B
This feature helps prevent a negative transient on the output
voltage when the output is shut down, eliminating the
Schottky diode that is used in some systems for protecting
the load from reversed output voltage events.
In addition, more than 400mV hysteresis also incorporates
into the three-state shutdown window to eliminate PWM
input oscillations due to the capacitive load seen by the
PWM input through the body diode of the controller ’s PWM
output when the power-up and/or power-down sequence of
As an example, suppose two IRLR7821 FETs are chosen as
the upper MOSFETs. The gate charge, Q G , from the data
sheet is 10nC at 4.5V (V GS ) gate-source voltage. Then the
Q GATE is calculated to be 53nC for UVCC (i.e. PVCC in
ISL6613B, VCC in ISL6612B) =12V. We will assume a
200mV droop in drive voltage over the PWM cycle. We find
that a bootstrap capacitance of at least 0.267 μ F is required.
1.6
1.4
bias supplies of the driver and PWM controller are required.
1.2
Power-On Reset (POR) Function
During initial start-up, the VCC voltage rise is monitored.
Once the rising VCC voltage exceeds 6.9V (typically),
operation of the driver is enabled and the PWM input signal
takes control of the gate drives. If VCC drops below the
falling threshold of 5.6V (typically), operation of the driver is
disabled.
1.
0.8
0.6
0.4
Q GATE = 100nC
50nC
Pre-POR Overvoltage Protection
0.2
20nC
Prior to VCC exceeding its POR level, the upper gate is held
low and the lower gate is controlled by the overvoltage
0.0
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
protection circuits during initial startup. The PHASE is
connected to the gate of the low side MOSFET (LGATE),
which provides some protection to the microprocessor if the
upper MOSFET(s) is shorted during initial start-up. For
complete protection, the low side MOSFET should have a
gate threshold well below the maximum voltage rating of the
load/microprocessor.
When VCC drops below its POR level, both gates pull low
and the Pre-POR overvoltage protection circuits are not
activated until VCC resets.
Internal Bootstrap Device
Both drivers feature an internal bootstrap schottky diode.
Simply adding an external capacitor across the BOOT and
PHASE pins completes the bootstrap circuit. The bootstrap
function is also designed to prevent the bootstrap capacitor
from overcharging due to the large negative swing at the
trailing-edge of the PHASE node. This reduces voltage
stress on the boot to phase pins.
The bootstrap capacitor must have a maximum voltage
rating above UVCC + 5V and its capacitance value can be
chosen from the following equation:
Δ V BOOT_CAP (V)
FIGURE 2. BOOTSTRAP CAPACITANCE vs BOOT RIPPLE
VOLTAGE
Gate Drive Voltage Versatility
The ISL6612B and ISL6613B provide the user flexibility in
choosing the gate drive voltage for efficiency optimization.
The ISL6612B upper gate drive can be driven above VCC
rising POR (7V) to 12V, but the lower drive rail can range
from 12V down to 5V depending on what voltage is applied
to PVCC. The ISL6613B ties the upper and lower drive rails
together. Simply applying a voltage from 5V up to 12V on
PVCC sets both gate drive rail voltages simultaneously.
Power Dissipation
Package power dissipation is mainly a function of the
switching frequency (F SW ), the output drive impedance, the
external gate resistance, and the selected MOSFET’s
internal gate resistance and total gate charge. Calculating
the power dissipation in the driver for a desired application is
critical to ensure safe operation. Exceeding the maximum
allowable power dissipation level will push the IC beyond the
maximum recommended operating junction temperature of
C BOOT_CAP ≥ --------------------------------------
Q GATE
Δ V BOOT_CAP
(EQ. 1)
+125°C. The maximum allowable IC power dissipation for
the SO8 package is approximately 800mW at room
temperature, while the power dissipation capacity in the
Q GATE = ------------------------------------ ? N Q1
Q G1 ? UVCC
V GS1
where Q G1 is the amount of gate charge per upper MOSFET
at V GS1 gate-source voltage and N Q1 is the number of
control MOSFETs. The Δ V BOOT_CAP term is defined as the
allowable droop in the rail of the upper gate drive.
8
EPSOIC and DFN packages, with an exposed heat escape
pad, is more than 2W and 1.5W, respectively. Both EPSOIC
and DFN packages are more suitable for high frequency
applications. See Layout Considerations paragraph for
thermal transfer improvement suggestions. When designing
the driver into an application, it is recommended that the
following calculation is used to ensure safe operation at the
FN9205.4
May 1, 2012
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| ISL6612BIRZ-T | 功能描述:IC MOSFET DRVR SYNC BUCK 10-DFN RoHS:是 类别:集成电路 (IC) >> PMIC - MOSFET，电桥驱动器 - 外部开关 系列:- 标准包装:6,000 系列:* |
| ISL6612CB | 功能描述:IC MOSFET DRVR SYNC BUCK 8-SOIC RoHS:否 类别:集成电路 (IC) >> PMIC - MOSFET，电桥驱动器 - 外部开关 系列:- 标准包装:50 系列:- 配置:低端 输入类型:非反相 延迟时间:40ns 电流 - 峰:9A 配置数:1 输出数:1 高端电压 - 最大（自引导启动）:- 电源电压:4.5 V ~ 35 V 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:TO-263-6，D²Pak（5 引线+接片），TO-263BA 供应商设备封装:TO-263 包装:管件 |
| ISL6612CB-T | 功能描述:IC MOSFET DRVR SYNC BUCK 8-SOIC RoHS:否 类别:集成电路 (IC) >> PMIC - MOSFET，电桥驱动器 - 外部开关 系列:- 标准包装:50 系列:- 配置:低端 输入类型:非反相 延迟时间:40ns 电流 - 峰:9A 配置数:1 输出数:1 高端电压 - 最大（自引导启动）:- 电源电压:4.5 V ~ 35 V 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:TO-263-6，D²Pak（5 引线+接片），TO-263BA 供应商设备封装:TO-263 包装:管件 |
| ISL6612CBZ | 功能描述:IC DRVR MOSF SYNC BUCK OTP 8SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - MOSFET，电桥驱动器 - 外部开关 系列:- 标准包装:6,000 系列:* |
| ISL6612CBZA | 功能描述:IC MOSFET DRVR SYNC BUCK 8-SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - MOSFET，电桥驱动器 - 外部开关 系列:- 标准包装:6,000 系列:* |
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