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PDF A1667LLTR-T Data sheet ( Hoja de datos )
| Número de pieza | A1667LLTR-T | |
| Descripción | Ring Magnet Sensor IC | |
| Fabricantes | Allegro | |
| Logotipo |  |
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A1667
True Zero-Speed, High Accuracy, Ring Magnet Sensor IC
FEATURES AND BENEFITS
▪ Optimized robustness to magnetic offset variation
▪ Small signal lockout for immunity against vibration
▪ Tight duty cycle and timing accuracy over full operating
temperature range
▪ True zero-speed operation
▪ Air gap independent switch points
▪ Large operating air gaps achieved through use of gain
adjust and offset adjust circuitry
▪ Defined power-on state (POS)
▪ Wide operating voltage range
▪ Digital output representing target profile
▪ Single chip sensing IC for high reliability
▪ Small mechanical size
▪ Fast startup
▪ Undervoltage lockout (UVLO)
Packages:
8-Pin SOIC (suffix L)
4-Pin SIP (suffix K)
Not to scale
DESCRIPTION
The A1667 is a true zero-speed ring magnet sensor integrated
circuit (IC) consisting of an optimized Hall IC available in
two package options that provides a user-friendly solution for
digital ring magnet sensing applications.
The sensor incorporates a dual element Hall IC that switches
in response to differential magnetic signals created by a
ring magnet. The IC contains a sophisticated compensating
circuit designed to eliminate the detrimental effects of magnet
and system offsets. Digital processing of the analog signal
provides zero-speed performance independent of air gap and
also dynamic adaptation of device performance to the typical
operating conditions found in automotive applications (reduced
vibration sensitivity). High-resolution peak detecting DACs
are used to set the adaptive switching thresholds of the device.
Hysteresis in the thresholds reduces the negative effects of any
anomalies in the magnetic signal associated with the targets
used in many automotive applications.
The open-drain output is configured for three-wire applications.
This sensor is ideal for obtaining speed and duty cycle
Continued on the next page…
KEY APPLICATIONS
• Automotive – Transmissions Applications
• 2- and 3-Wheeler Speed Applications
• White Goods – Drum Speed Applications
Functional Block Diagram
VCC
Voltage
Regulator
Hall
Amp
Offset
Adjust
Automatic
Gain
Control
VPROC
PDAC
NDAC
PThresh
Reference
Generator
NThresh
Threshold
Comparator
Threshold
Logic
TEST
A1667-DS, Rev. 1
GND
Current
Limit
Output
Transistor
VOUT
1 page  
A1667
True Zero-Speed, High Accuracy, Ring Magnet Sensor IC
Characteristic Performance
Supply Current (Off) versus Ambient Temperature
14
12
10
VCC (V)
84
12
6 24
4
2
0
-50
0 50 100 150
TA (°C)
Supply Current (On) versus Ambient Temperature
14
12
10
VCC (V)
84
6 12
24
4
2
0
-50
0 50 100 150
TA (°C)
Output Saturation Voltage versus Ambient Temperature
VCC = 12 V
180
160
140
120
100
80
60
40
20
0
-50 0 50 100 150
TA (°C)
Supply Current (Off) versus Supply Voltage
14
12
10
TA (°C)
8 –40
25
6 150
4
2
0
0 10 20 30
VCC (V)
Supply Current (On) versus Supply Voltage
14
12
10
8
6
4
2
0
0
10 20
VCC (V)
TA (°C)
–40
25
150
30
Switchpoints versus Ambient Temperature
100
90
80
70
60
50
40
30
20
10
0
-50
BOP
BRP
0 50 100
TA (°C)
150
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
5
5 Page 
A1667
True Zero-Speed, High Accuracy, Ring Magnet Sensor IC
UNDERVOLTAGE LOCKOUT
When the supply voltage falls below the undervoltage lockout
voltage, VCC(UV) , the device enters Reset, where the output
state returns to the Power-On State (POS) until sufficient VCC
is supplied. ICC levels may not meet datasheet limits when VCC
< VCC(min). This lockout feature prevents false signals, caused
by undervoltage conditions, from propagating to the output of the
IC.
POWER SUPPLY PROTECTION
The device contains an on-chip regulator and can operate over a
wide VCC range. For devices that must operate from an unregu-
lated power supply, transient protection must be added externally.
For applications using a regulated line, EMI/RFI protection may
still be required. Contact Allegro for information on the circuitry
needed for compliance with various EMC specifications. Refer
to figure 7 for an example of a basic application circuit.
AUTOMATIC GAIN CONTROL (AGC)
This feature allows the device to operate with an optimal internal
electrical signal, regardless of the air gap (within the AG speci-
fication). At power-on, the device determines the peak-to-peak
amplitude of the signal generated by the target. The gain of the IC
is then automatically adjusted. Figure 8 illustrates the effect of
this feature.
AUTOMATIC OFFSET ADJUST (AOA)
The AOA circuitry automatically compensates for the effects of
chip, magnet, and installation offsets. This circuitry is continu-
ously active, including during both power-on mode and running
mode, compensating for any offset drift (within the Allowable
User Induced Differential Offset). Continuous operation also
allows it to compensate for offsets induced by temperature varia-
tions over time.
RUNNING MODE LOCKOUT
The A1667 has a running mode lockout feature to prevent switch-
ing in response to small signals that are characteristic of vibra-
tion signals. The internal logic of the chip considers small signal
amplitudes below a certain level to be vibration. The output is
held to the state prior to lockout until the amplitude of the signal
returns to normal operational levels.
VCC
CBYPASS
0.1 µF
(Optional)
A1667
1 VCC
VOUT 2
GND TEST
43
VPULLUP
RL
CL
Target
Ring Magnet
V+
Internal Differential
Analog Signal
Response, without AGC
V+
Internal Differential
Analog Signal
Response, with AGC
N SNS
AGLarge
AGSmall
AGSmall
AGLarge
Figure 7. Typical circuit for proper device operation.
Figure 8. Automatic Gain Control (AGC). The AGC function corrects for
variances in the air gap. Differences in the air gap cause differences in
the magnetic field at the device, but AGC prevents that from affecting
device performance, as shown in the lowest panel.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
11
11 Page | ||
| Páginas | Total 15 Páginas | |
| PDF Descargar | [ Datasheet A1667LLTR-T.PDF ] | |
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