5秒后页面跳转
A89503KLPTR-5 PDF预览

A89503KLPTR-5

更新时间: 2024-10-28 20:06:27
品牌 Logo 应用领域
急速微 - ALLEGRO /
页数 文件大小 规格书
45页 2739K
描述
Motion Control Electronic,

A89503KLPTR-5 技术参数

生命周期:ActiveReach Compliance Code:compliant
Base Number Matches:1

A89503KLPTR-5 数据手册

 浏览型号A89503KLPTR-5的Datasheet PDF文件第37页浏览型号A89503KLPTR-5的Datasheet PDF文件第38页浏览型号A89503KLPTR-5的Datasheet PDF文件第39页浏览型号A89503KLPTR-5的Datasheet PDF文件第41页浏览型号A89503KLPTR-5的Datasheet PDF文件第42页浏览型号A89503KLPTR-5的Datasheet PDF文件第43页 
A89503  
80 V Automotive Half-Bridge MOSFET Driver  
APPLICATION INFORMATION  
Bootstrap Capacitor Selection  
CBOOT × ∆V  
tCHARGE  
=
The A89503 requires a bootstrap capacitor C. To simplify this  
description of the bootstrap capacitor selection criteria, generic  
naming is used here. So, for example, CBOOT, QBOOT, and VBOOT  
refer to the bootstrap capacitor, and QGATE refers to the high-side  
MOSFET. CBOOT must be correctly selected to ensure proper  
operation of the device—too large and time will be wasted charg-  
ing the capacitor, resulting in a limit on the maximum duty cycle  
and PWM frequency; too small and there can be a large volt-  
age drop at the time the charge is transferred from CBOOT to the  
MOSFET gate.  
100  
where CBOOT is the value of the bootstrap capacitor in nF and ∆V  
is the required voltage of the bootstrap capacitor. At power up and  
when the drivers have been disabled for a long time, the bootstrap  
capacitor can be completely discharged. In this case, ∆V can be  
considered to be the full high-side drive voltage, 12 V. Otherwise,  
∆V is the amount of voltage dropped during the charge transfer,  
which should be 400 mV or less. The capacitor is charged when-  
ever the S terminal is pulled low and current flows from the capaci-  
tor connected to the VREG terminal through the internal bootstrap  
To keep the voltage drop due to charge sharing small, the charge  
in the bootstrap capacitor, QBOOT, should be much larger than  
QGATE, the charge required by the gate:  
diode circuit to CBOOT  
.
VREG Capacitor Selection  
QBOOT >> QGATE  
A factor of 20 is a reasonable value, so  
QBOOT = CBOOT × VBOOT = QGATE × 20  
The internal reference, VREG, supplies current for the low-side  
gate-drive circuits and the charging current for the bootstrap  
capacitors. When a low-side MOSFET is turned on, the gate-  
drive circuit will provide the high transient current to the gate that  
is necessary to turn the MOSFET on quickly. This current, which  
can be several hundred milliamperes, cannot be provided directly  
by the limited output of the VREG regulator but must be supplied  
by an external capacitor, CREG, connected between the VREG  
terminal and GND.  
or  
QGATE × 20  
CBOOT  
=
VBOOT  
where VBOOT is the voltage across the bootstrap capacitor.  
The turn-on current for the high-side MOSFET is similar in value  
but is mainly supplied by the bootstrap capacitor. However, the  
bootstrap capacitor must then be recharged from CREG through  
the VREG terminal. Unfortunately, the bootstrap recharge can  
occur a very short time after the low-side turn on occurs. This  
means that the value of CREG between VREG and GND should  
be high enough to minimize the transient voltage drop on  
VREG for the combination of a low-side MOSFET turn on and  
a bootstrap capacitor recharge. For block commutation control  
(trapezoidal drive), where only one high side and one low side  
are switching during each PWM period, a minimum value of 20 ×  
CBOOT is reasonable. For sinusoidal control schemes, a minimum  
value of 40 × CBOOT is recommended. As the maximum work-  
ing voltage of CREG will never exceed VREG, the part’s voltage  
rating can be as low as 15 V. However, it is recommended that  
a capacitor rated to at least twice the maximum working volt-  
age should be used to reduce any impact operating voltage may  
have on capacitance value. For best performance, CREG should be  
ceramic rather than electrolytic. CREG should be mounted as close  
to the VREG terminal as possible.  
The voltage drop, ∆V, across the bootstrap capacitor as the MOS-  
FET is being turned on, can be approximated by:  
QGATE  
V  
=
CBOOT  
so for a factor of 20, ∆V will be 5% of VBOOT  
.
The maximum voltage across the bootstrap capacitor under  
normal operating conditions is VREG (max). However in some  
circumstances the voltage may transiently reach a maximum of  
18 V, which is the clamp voltage of the Zener diode between the  
C terminal and the S terminal. In most applications with a good  
ceramic capacitor, the working voltage can be limited to 16 V.  
Bootstrap Charging  
It is necessary to ensure the high-side bootstrap capacitor is com-  
pletely charged before a high-side PWM cycle is requested. The time  
required to charge the capacitor, tCHARGE, in µs, is approximated by:  
40  
Allegro MicroSystems  
955 Perimeter Road  
Manchester, NH 03103-3353 U.S.A.  
www.allegromicro.com  

与A89503KLPTR-5相关器件

型号 品牌 获取价格 描述 数据表
A8951CLW ETC

获取价格

Servo Motor Controller/Driver
A8952CLW ETC

获取价格

Servo Motor Controller/Driver
A8958CEA ETC

获取价格

Servo Motor Controller/Driver
A8958CLB ALLEGRO

获取价格

VOICE COIL MOTOR DRIVER
A8958CLBTR ALLEGRO

获取价格

Voice Coil Motor Controller, 1A, PDSO24, BATWING, POWER, SOIC-24
A8958CLW ETC

获取价格

Industrial Control IC
A8958SEA ALLEGRO

获取价格

Voice Coil Motor Controller, 1A, BIPolar, PQCC28, POWER, PLASTIC, LCC-28
A8980 ETC

获取价格

Peripheral IC
A8980CJT ALLEGRO

获取价格

SUPERSERVO SPINDLE & VOICE-COIL ACTUATION MANAGER/DRIVER
A-8981-4R-1-LF MOLEX

获取价格

5.08mm (.200") Pitch Disk Drive Power Connection System Header, Right Angle, Through Hole,