파트넘버.co.kr A4255CA 데이터시트 PDF


A4255CA 반도체 회로 부품 판매점

8-BIT MICROCONTROLLER



Allegro MicroSystems 로고
Allegro MicroSystems
A4255CA 데이터시트, 핀배열, 회로
4255
A4255CA
MODE SELECT1 1
MODE SELECT2 2
STEP IN 3
RESET 4
GROUND 5
MONITOR OUT 6
SHIFT CLOCK
SERIAL DATA OUT
7
8
STROBE OUT 9
18 MODE SELECT0
DIRECTION
17 CONTROL IN
16 OSC/CLOCK IN
15 OSC/CLOCK OUT
VDD 14 SUPPLY
13 PFDA
12 PHASEA
11 PFDB
10 PHASEB
Dwg. PP-071A
ABSOLUTE MAXIMUM RATINGS
Supply Voltage, VDD .......................... 7.0 V
Input Voltage Range,
VI ........................ -0.3 V to VDD + 0.6 V
RESET Voltage, VRESET ...................... 14 V
Input Clamp Current, IIK ............... ±20 mA
Output Clamp Current, IOK ............ ±20 mA
Operating Temperature Range,
TA .................................... 0°C to +70°C
Storage Temperature Range,
TS .............................. -55°C to +150°C
Caution: These CMOS devices have input
static protection (Class 3) but are still
susceptible to damage if exposed to extremely
high static electrical charges.
8-BIT
MICROCONTROLLER
The A4255CA and A4255CLN microcontrollers make designing
with step motors easy, inexpensive, and productive. A reference design
technique is integral to the implementation of a system that includes the
power circuitry, a low-cost, 8-bit, preprogrammed microcontroller and
the other components needed to complete the control hardware. The
A4255Cx eliminates the need for software development, expedites the
product creation, and hastens the time to market.
The reference design can be utilized directly or integrated into a
larger printed wiring board. A further benefit is the compactness of the
circuit layout. Power-driver output ratings presently available with these
devices are 50 V and ±1.5 A (with the A3955 or A3957). A similar
device for 46 V and either 1.5 A (with the SLA7042M) or 3 A (with the
SLA7044M) is planned. The reference design supports stepping formats
that include full-step, half-step, quarter-step, eighth-step, and sixteenth-
step (microstepping) increments for a two-phase stepping motor.
The A4255CA is furnished in an 18-pin dual in-line plastic package
for through-hole applications. The A4255CLN is furnished in a 20-lead
wide-body, shrink-pitch, small-outline plastic package (SSOP) with gull-
wing leads for minimum area, surface-mount applications.
FEATURES
I Full-, Half-, Quarter-, Eighth-, or Sixteenth-Step Increments
I DC to 20 MHz Clock Input
I Power-On Reset
I Brown-Out Reset
I High-Speed CMOS Technology
I Low Power, <20 mA @ 5 V, 20 MHz
(Typically 9 mA)
Always order by complete part number:
Part Number
A4255CA
A4255CLN
Package
18-pin DIP
20-lead shrink-pitch SOIC


A4255CA 데이터시트, 핀배열, 회로
4255
8-BIT
MICROCONTROLLER
A4255CLN
0.65 mm (0.026”) pitch
MODE SELECT1 1
MODE SELECT2 2
STEP IN 3
RESET 4
GROUND 5
GROUND 6
MONITOR OUT 79
SHIFT CLOCK 8
SERIAL DATA OUT 9
STROBE OUT 10
20 MODE SELECT0
DIRECTION
19 CONTROL IN
18 OSC/CLOCK IN
17 OSC/CLOCK OUT
VDD 16 SUPPLY
VDD 15 SUPPLY
14 PFDA
13 PHASEA
12 PFDB
11 PHASEB
Dwg. PP-071-1
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
FUNCTIONAL DESCRIPTION
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.
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
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
Copyright © 2000, Allegro MicroSystems, Inc.




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A4255CA controller

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A4255CA

8-BIT MICROCONTROLLER - Allegro MicroSystems



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8-BIT MICROCONTROLLER - Allegro MicroSystems