Allegro MicroSystems A1569 User manual

User Manual
A1569 Proto Board
Overview
The A1569 is a unique integrated circuit which combines an
ultrasensitive Hall-effect switch with a linear programmable
current regulator which provides up to 150 mA for driving a
string of high brightness LEDs. This document accompanies
the Allegro A1569 Proto Board. The A1569 Proto Board is
intended to provide the user with a small format platform
for integrating the A1569 into their own prototype designs.
Refer to the latest A1569 datasheet for the operational speci-
fications of the A1569.
Description
The A1569 Proto Board is a small two-layer double-sided
PCB with the A1569 mounted on the front of the board. All
of the basic components are provided. If the A1569 Proto
Board is ordered with an LED installed (see below), the
only requirement is to connect power (VIN) and ground
(GND) via two of the through-hole connections on P1 (see
Figure 1, Figure 2, and Figure 3).
By Peter Tengstrand
Allegro MicroSystems, LLC
Through-hole connections are provided for all of the exter-
nal connections that may be required for the target applica-
tion. All of the through-hole connections with square pads,
which are not labeled, are the ground connections. The
remaining through-hole connections, the ones with round
pads, are labeled for convenience on the bottom side of the
board (see Figure 3).
A mounting hole for a #2 screw is also provided (see upper-
right corner of Figure 2 and upper-left corner of Figure 3).
This screw should be nonferrous to prevent interference
with the operation of the Hall element.
LED Placement
There are three placement options for the LED supported by
the A1569 Demo Board. Only one option should be selected
at any given time, as the A1569 is designed to drive a single
string of LEDs.
The A1569 Proto Board can be ordered with an LED pre-
installed on the front side of the board (the same side as
A1569KLJ-T
LED1
Front
LED2
Back
External
LED
LA
CBYPASS
0.1 µF
CFADE
1 µF
P1
P2
3
2
1
3
2
1
SEN_EN
EXT
FADE
IREF
THTH
RIREF
4.7 kΩ
RSEN_EN
4.7 kΩ
VIN
RTHTH
0 Ω (optional)
LA 2
1
41
2
3
5
6
7
9
8
SEN_EN
EXT
FADE
IREF
THTH
PAD
GND
VIN LA
Figure 1: A1569 Proto Board Schematic
ASEK1569-UM

2
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
the A1569 as shown in Figure 2), pre-installed on the back side
of the board (the opposite side as the A1569 as shown in Figure
3), or with no LED installed (for the case where the LED will be
remotely located from the A1569).
Figure 2: A1569 Proto Board – Top
Figure 3: A1569 Proto Board – Bottom
Basic Connections
The basic connections are boxed and labeled P1 on the front of
the board (see the upper-left corner of Figure 2). This is where
the power and ground connections are made. By turning the
board over, additional labelling can be seen (see the upper-right
corner of Figure 3).
• Ground should be connected to the square pad (which has no
additional labelling).
• VIN should be connected to the middle pad, which is round
and is labeled on the bottom.
• If the application requires the Hall Element be selectively
enabled and disabled, then a connection to SEN_EN can be
made to the remaining round pad.
Connecting Remote LEDs
The A1569 Proto Board provides through-holes for connecting a
string of LEDs which can be mounted remotely from the A1569
Proto Board. To make use of this feature, no other LED should be
mounted on the A1569 Proto Board.
The through-holes for connecting the remote LED string are
boxed and labeled LA on the front of the board (see the lower-left
corner of Figure 2).
• The cathode of the remote LED string should be connected
to the hole with the square pad (which has no additional
labelling).
• The anode of the remote LED string should be connected to
the remaining hole with the round pad (labeled LA on the back
of the board; see Figure 3).
Connecting an External Hall Switch
It is possible to override the A1569 internal Hall element and
turn on the LED output current by driving the EXT input of the
A1569. This allows for a second sensing point, remote from
the A1569, to control the LED string connected to the A1569.
Allegro provides a separate A1126 Proto Board as a mate to the
A1569 Proto Board for this application. Contact your Allegro
sales representative for information on obtaining one of these
boards.
The connections for the external Hall element is boxed and
labeled on the bottom of the A1569 Proto Board (see right-hand
side of Figure 3).
The connections to the A1126 Proto Board are as follows:
• The grounds of the two boards should be connected together
using the square pads (which have no additional labelling).
• The OUT of the A1126 Proto Board should be connected to
EXT of the A1569 Proto Board. Both of these connections are
labeled on the bottom side of their respective boards and are
the middle connections with the round pads.
• The VOUT of the A1569 Proto Board should be connected to
the VIN of the A1126 Proto Board using the remaining round
pads. Both are labeled on the bottom side of their respective
boards.
Refer to the A1126 Proto Board User’s Guide for more informa-
tion.

3
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
For the latest version of this document, visit our website:
www.allegromicro.com
Copyright ©2016, Allegro MicroSystems, LLC
The information contained in this document does not constitute any representation, warranty, assurance, guaranty, or inducement by Allegro to the
customer with respect to the subject matter of this document. The information being provided does not guarantee that a process based on this infor-
mation will be reliable, or that Allegro has explored all of the possible failure modes. It is the customer’s responsibility to do sufficient qualification
testing of the final product to insure that it is reliable and meets all design requirements.
Revision History
Number Date Description
– May 3, 2016 Initial release