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参数资料
| 型号： | 4255 |
| 厂商： | Allegro MicroSystems, Inc. |
| 英文描述： | OSC 5V 14PIN TTL |
| 中文描述： | 8位微控制器 |
| 文件页数： | 2/8页 |
| 文件大小： | 142K |
| 代理商： | 4255 |
4255
8-BIT
MICROCONTROLLER
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
Copyright 2000, Allegro MicroSystems, Inc.
A4255CLN
0.65 mm (0.026”) pitch
RECOMMENDED OPERATING CONDITIONS
over operating temperature range
Logic Supply Voltage Range, VDD ............... 4.5 V to 5.5 V
High-Level Input Voltage, VIH ............................ ≥ 0.85VDD
Low-level input voltage, VIL ................................. ≤0.15VDD
Dwg. PP-071-1
PFDA
PHASEA
PFDB
PHASEB
MONITOR OUT
SHIFT CLOCK
SERIAL DATA OUT
STROBE OUT
MODE SELECT0
DIRECTION
CONTROL IN
OSC/CLOCK IN
OSC/CLOCK OUT
SUPPLY
VDD
GROUND
MODE SELECT1
MODE SELECT2
STEP IN
RESET
19
15
6
1
2
3
4
5
10
14
13
12
11
20
18
17
16
9
8
79
SUPPLY
VDD
GROUND
To ease and simplify the design effort, the user only
provides the following signals: (a) direction, (b) stepping
clock (8x the full-step frequency), (c) mode logic (three
inputs determine the operation for full, half, quarter, or
eighth stepping), (d) reset input (initiates a ‘detent’
position), and (e) recirculation control (this allows estab-
lishing the percent of fast- vs slow-decay in the phase
winding). The microcontroller program providess auto-
matic recirculation control. This eliminates the need for
evaluating the impact of stepping rate vs the sinusoidal
current profile.
Although recirculation control can provide slight
improvements (i.e., lower current ripple, reduced motor
heating [a few degrees], and diminish audible noise levels
[minimal differences]), this entails an evaluation of the
motor (and step frequencies) to determine the proper ratio
of fast- and slow-decay. The benefits of tuning the
recirculation ratios are small, and the time and effort
required can be considerable. Hence, the uninitiated user
should opt for the automatic recirculation control, and
avoid the essentially unnecessary activity.
FUNCTIONAL DESCRIPTION
MICROCONTROLLER OPERATION
Although ‘hardware’ control of the microstepping ICs
is feasible, without a specific (ASIC), monolithic IC
controller the prime solution becomes a ‘software’ option.
From the user’s perspective, a ‘preprogrammed’ micro-
controller appears little, or no, different than a ‘dedicated’
controller and sequencer IC expressly created for mi-
crostepping applications of the power-driver ICs. Further,
the flexibility of a software-based drive is certainly a basic
benefit (high-volume production of 8-bit microcontrollers
transposes to low-cost circuitry).
As an indicator of the logic signals needed to control
the power ICs, Table 1 lists the required A3955 inputs to
the 3-bit DAC for eighth-step operation (the similar
A3957 uses a 4-bit DAC for sixteenth-step operation).
These I/O signals are serial data from the microcontroller,
then converted to a parallel mode by a 74HC595 as the
‘interface’ between the microcontroller and the two
microstepping power ICs.
The versatility offered by software control allows the
operating modes listed in Table 1. This table itemizes the
various logic inputs that determine direction, stepping
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相关代理商/技术参数 |
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|---|---|
| 4255 | 制造商:3M Electronic Products Division 功能描述:RESPIRATOR A2P2 |
| 42550 | 制造商:Desco Industries Inc 功能描述:MAT 3-LYR VNYL BL .125''X16''X24 制造商:Desco Industries Inc 功能描述:MAT, STATFREE Z2, 3-LAYER VINYL, BLUE, 0.125x16x24 |
| 425-50,8MM(R06933) | 制造商:3M Electronic Products Division 功能描述:Aluminium adhesive tape 3M 425 50 mm |
| 425-5020-530 | 制造商:TERADYNE 功能描述:HEADER CONNECTOR,PCB MNT,RECEPT,80 CONTACTS,PIN,0.100 PITCH,PC TAIL TERMINAL |
| 42550X55 | 制造商:3M Electronic Products Division 功能描述:425 aluminium foil tape,55m Lx50mm W |
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