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UDN2961B 参数 Datasheet PDF下载

UDN2961B图片预览
型号: UDN2961B
PDF下载: 下载PDF文件 查看货源
内容描述: 大电流半桥打印头/电机DRIVER.WITH内部电流传感与控制 [HIGH-CURRENT HALF-BRIDGE PRINTHEAD/MOTOR DRIVER.WITH INTERNAL CURRENT SENSING AND CONTROL]
分类和应用: 运动控制电子器件信号电路光电二极管电动机控制电机驱动
文件页数/大小: 12 页 / 95 K
品牌: ALLEGRO [ ALLEGRO MICROSYSTEMS ]
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2961  
HIGH-CURRENT  
HALF-BRIDGE  
PRINTHEAD/MOTOR DRIVER  
A logic high on the MODE pin sets the  
current-control circuitry into the fast-decay  
mode. When the peak current threshold is  
detected, the flip-flop is reset and both the  
source driver and the sink driver turn OFF.  
Load current decays quickly through the  
external ground clamp diode, the load, and  
the internal flyback diode. In the fast-  
decay mode, the OFF time period is one-  
half the time that is set by the external RC  
network for the slow-decay mode:  
V
REF  
V
16  
1
2
BB  
15  
14  
13  
12  
11  
10  
9
INPUT  
3
4
CURRENT-  
CONTROL  
LOGIC  
2940  
±1%  
V
BB  
5
6
V
BB  
ENABLE  
MODE  
47 µF  
RC  
2
tOFF  
=
7
8
V
CC  
The amount of ripple current, when  
chopping in the fast-decay mode, is  
considerably higher than when chopping in  
the slow-decay mode.  
+5 V  
R
V
C
16  
15  
14  
13  
12  
11  
1
2
BB  
The frequency of the PWM current  
control is determined by the time required  
for the load current to reach the set peak  
threshold (a function of the load character-  
istics and VBB) plus the OFF time of the  
switching driver(s) (set by the external RC  
components).  
INPUT  
3
4
CURRENT-  
CONTROL  
LOGIC  
47 µF  
5
6
V
BB  
To prevent false resetting of the flip-  
flop, due to switching transients and noise,  
a blanking time for the comparator can be  
set by the user where tB 3600 x C in the  
slow-decay mode or tB 2400 x C in the  
fast-decay mode. For C between 100 pF  
and 1000 pF, tB is in µs.  
V
BB  
C
7
8
10  
9
V
CC  
+5 V  
Dwg. EP-038A  
R
POWER CONSIDERATIONS  
The UDN2961B/W outputs are opti-  
mized for low power dissipation. The sink  
driver has a maximum saturation voltage  
drop of only 1.4 V at 3.4 A, while the  
and the sink driver) may be greater than 50%, and the power dissipa-  
tion will be greater.  
GENERAL  
source driver has a 2.2 V drop at -3.4 A.  
Device power dissipation is minimized in  
the slow-decay mode, as the chopping  
driver (the source driver) is ON for less  
than 50% of the chop period. When the  
source driver is OFF during a chop cycle,  
power is dissipated on chip only by the sink  
driver; the rest of the power is dissipated  
through the external ground clamp diode.  
In the fast-decay mode, the ON time of the  
chopping drivers (both the source driver  
A logic low on the ENABLE pin prevents the source driver and the  
sink driver from turning ON, regardless of the state of the INPUT pin or  
the supply voltages. With the ENABLE pin high, a logic low on the  
INPUT pin turns ON the output drivers.  
To protect against inductive load voltage transients, an external  
ground clamp diode is required. A fast-recovery diode is recom-  
mended to reduce power dissipation in the UDN2961B/W. The blank-  
ing time prevents false triggering of the current sense comparator,  
which can be caused by the recovery current spike of the ground  
clamp diode when the chopping source driver turns ON.