A1340 Datasheet

A1340
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
FEATURES AND BENEFITS
DESCRIPTION
• Advanced 32-segment output linearization functionality
enables high output accuracy and linearity in the
presence of non-linear input magnetic fields
• Customer adjustable sensitivity and offset, bandwidth,
output clamps, and 1st and 2nd order temperature
compensation
• Simultaneous programming of all parameters for accurate
and efficient system optimization
• Factory trimmed magnetic input range (coarse sensitivity)
and signal offset
• Sensitivity temperature coefficient and magnetic offset drift
preset at Allegro, for maximum device accuracy without
requiring customer temperature testing
• Temperature-stable, mechanical stress immune, and
extremely low noise device output via proprietary
four-phase chopper stabilization and differential circuit
design techniques
• Diagnostics for open circuit and undervoltage
• Wide ambient temperature range: –40°C to 150°C
• Operates with 4.5 to 5.5 V supply voltage
The A1340 device is a high precision, programmable Hall
effect linear sensor integrated circuit (IC) for both automotive
and non-automotive applications. The signal path of the A1340
provides flexibility through external programming that allows
the generation of an accurate, and customized output voltage
from an input magnetic signal. The A1340 provides 12 bits of
output resolution, and supports a maximum bandwidth of 3 kHz.
Package: 4-pin SIP (suffix KT)
A key feature of the A1340 is its ability to produce a highly
linear device output for nonlinear input magnetic fields.
To achieve this, the device divides the output into 32 equal
segments and applies a unique linearization coefficient factor
to each segment. Linearization coefficients are stored in a
look-up table in EEPROM.
1 mm case thickness
The BiCMOS, monolithic integrated circuit incorporates a
Hall sensor element, precision temperature-compensating
circuitry to reduce the intrinsic sensitivity and offset drift of the
Hall element, a small-signal high-gain amplifier, proprietary
dynamic offset cancellation circuits, and advanced output
linearization circuitry.
With on-board EEPROM and advanced signal processing
functions, the A1340 provides an unmatched level of customer
reprogrammable options for characteristics such as gain and
offset, bandwidth, and output clamps. Multiple input magnetic
range and signal offset choices can be preset at the factory. In
addition, the device supports separate hot and cold, 1st and 2nd
order temperature compensation.
The A1340 sensor is available in a lead (Pb) free 4-pin single
in-line package (KT suffix), with 100% matte tin leadframe
plating.
Not to scale
Analog Subsystem
Digital Signal Processing
Output Stage
...00110011...
Magnetic
Signal
12-bit
Hall
Element
Factory Preset
Magnetic Range
and
Signal Offset
A to D
Conversion
Bandwidth
and
Temperature
Compensation
Sensitivity
and
Fine Offset
Adjustment
Linearization
Clamps
Figure 1: A1340 Signal Processing Path.
D to A
Conversion
Functions with programmable parameters indicated by double-headed arrows.
A1340-DS, Rev. 2
Output
Voltage
12-bit
Output
Driver
A1340
Selection Guide
Part Number
A1340LKTTN-4-T
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
Packing*
4000 pieces per 13-in. reel
*Contact Allegro™ for additional packing options
Specifications
Absolute Maximum Ratings
Thermal Characteristics
Functional Block Diagram
Pin-out Diagram and Terminal List
Electrical Characteristics
Magnetic Characteristics
Programmable Characteristics
Thermal Characteristics
Characteristic Performance
Functional Description
Signal Processing Parameter Setting
Digital Signal Processing
Bandwidth Selection
Temperature Compensation
Digital Output Sensitivity (Gain) Adjustment
Output Fine Offset Adjustment
Linearization of Output
Output Polarity
Output Signal Clamps Setting
Protection Features
Typical Application
Programming Serial Interface
Transaction Types
Writing the Access Code
Writing to Non-Volatile EEPROM 3
3
3
4
4
5
6
7
10
11
14
14
14
14
14
16
16
16
17
18
18
18
19
19
19
19
Table of Contents
Writing to Volatile Registers
20
Reading from EEPROM
20
Error Checking
20
Serial Interface Reference
21
Serial Interface Message Structure
22
Read23
Read Acknowledge
24
Write24
Write Access Code
25
Write Disable Code
25
Write Enable Code
26
EEPROM Structure
27
Definitions of Terms
37
Package Outline Drawing
40
EEPROM Customer-Programmable Parameter
Reference
29
Power-On Time, tPO37
Respnse TIme, tRESP37
Quiescent Voltage Output (QVO), VOUT(Q)37
Sensitivity, Sens
37
Magnetic Offset Drift Through Temperature Range 37
Sensitivity Drift Through Temperature Range
38
Sensitivity Drift Due to Package Hysteresis,
DSensPKG38
Linearity Sensitivity Error
38
Ratiometric38
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
2
A1340
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
SPECIFICATIONS
Absolute Maximum Ratings
Characteristic
Symbol
Notes
Rating
Unit
Forward Supply Voltage
VCC
19
V
Reverse Supply Voltage
VRCC
–20
V
Forward Supply Current
ICC
30
mA
Reverse Supply Current
IRCC
–30
mA
Forward Output Voltage (VOUT Pin)
VOUT
29
V
Reverse Output Voltage (VOUT Pin)
VROUT
–0.5
V
ISINK
50
mA
Forward Output Sink Current (VOUT Pin)
Maximum Number of EEPROM Write
Cycles
Maximum voltage depends on programmed voltage settings
EEPROMW(max)
100
cycle
Operating Ambient Temperature
TA
–40 to 150
ºC
Maximum Junction Temperature
TJ(max)
165
ºC
Tstg
–65 to 165
ºC
Storage Temperature
L temperature range
Thermal Characteristics may require derating at maximum conditions, see application information
Characteristic
Symbol
Test Conditions*
Value
Unit
Package Thermal Resistance
RθJA
1-layer PCB with copper limited to solder pads
174
ºC/W
*Additional thermal information available on the Allegro website.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
3
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
A1340
VCC
UVLO
Factory Coarse Sensitivity
and Magnetic Range
Setting
POR
Analog
Regulator
Factory
Coarse Offset
Trim
Digital
Regulator
Clock
Generator
EEPROM
Analog
Front End
Digital
Subsystem
ADC
Hall
Element
Serial
Decode
Anti-Alias
Filter
Temperature
Sensor
ADC
Precision
Reference
A/D
12
12
Serial
Interface
Bandwidth
Select
Temperature
Compensation
HV Pulse
Master
Control
Digital Sensitivity
and Offset Trim
Pulse
Detect
EEPROM
Control
Scan/
IDDQ
Linearization
Clamp
DAC
Driver
VOUT
GND
Functional Block Diagram
Pin-out Diagram and Terminal List Table
Terminal List Table
1
Number
Name
1
VCC
2
VOUT
3
NC
4
GND
Function
Input power supply, use bypass capacitor to connect to ground
Analog output pin; EEPROM strobe input
Not connected; connect to GND for optimal ESD performance
Device ground
2 3 4
Package KT, 4-Pin SIP
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
4
A1340
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
ELECTRICAL CHARACTERISTICS: valid through full operating temperature range, TA , and supply voltage, VCC ,
CBYPASS = 10 nF, unless otherwise specified
Characteristics
Symbol
Test Conditions
Min.
Typ.
Max.
Unit1
4.5
–
5.5
V
General Electrical Characteristics
Supply Voltage
Supply Current
Supply Zener Clamp Voltage
Hall Chopping
Frequency4
Undervoltage Lockout Threshold2
VCC
ICC
VZSUPPLY
fC
TA = 25°C; ICC = ICC(max) + 3 mA
5
–
15
mA
19
–
–
V
TA = 25°C
–
128
–
kHz
VCC(UV_low) TA = 25°C, UVLO falling
3.5
–
4.2
V
VCC(UV_high) TA = 25°C, UVLO rising
3.7
–
4.45
V
V
Output Electrical Characteristics
Output Saturation Voltage
Output Current Limit
Output Noise Peak to Peak3
VSAT(H)
ROUT = 10 kΩ to GND, VCC – VOUT ,TA = 25°C
–
0.2
0.3
VSAT(L)
ROUT = 10 kΩ to VCC, TA = 25°C
–
0.2
0.3
V
ILIMIT(SNK)
VOUT = VCC(max), TA = 25°C
25
35
42
mA
ILIMIT(SRC)
VOUT = GND, TA = 25°C
–4
–1.6
–
mA
–
6
–
mVpp
Vnpp
Output Zener Clamp Voltage
VZOUT
TA = 25°C
29
–
–
V
Output Load Resistance4
RLOAD
VOUT to VCC, VOUT to GND
10
–
–
kΩ
Output Load Capacitance4,5
CLOAD
VOUT to GND
–
–
10
nF
BW = 3000 Hz
–
0.6
0.75
ms
BW = 1500 Hz
–
1.1
1.4
ms
BW = 375 Hz
–
3.2
4.0
ms
BW = 3000 Hz
–
0.5
–
ms
BW = 1500 Hz
–
0.9
–
ms
BW = 375 Hz
–
3.24
–
ms
Power-On Time4,6,7
Response Time7,8
tPO
tRESP
11
G (gauss) = 0.1 mT (millitesla).
2See Protection Features section.
3Capacitor of 10 nF connected between output and ground.
4Determined by design.
5Clarity of a Read Acknowledge message from the device to the controller will be affected by the amount of capacitance and wire inductance on the device output. In such
case, it is recommended to slow down the communication speed, and to lower the receiver threshold for reading digital Manchester signal to 1 V.
6Defined as time from V
CC reaching VCC(min) to VOUT reaching 90% of its steady state. See Definitions of Terms section.
7Parameter is verified by lab characterization with a limited amount of samples.
8Defined time from step in gauss of applied magnetic field to V
OUT step reaching 90% of its steady state. See Definitions of Terms section.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
5
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
A1340
MAGNETIC CHARACTERISTICS: valid across full operating temperature range, TA , and supply voltage range, VCC ,
CBYPASS = 10 nF; unless otherwise specified
Characteristics
Factory Programmed Device
Symbol
Test Conditions
Min.
Typ.
Max.
Unit1
–
±300
–
G
Values2
Magnetic Input Signal Range
BIN
Magnetic Input Signal Offset
BINOFFSET
Output Sensitivity
Quiescent Voltage Output
Output Clamp Initial Voltage
Sensitivity Drift Over Temperature3
Offset (QVO) Drift Over Temperature4
SENS_COARSE = 4
–
0
–
V
SENS_MULT = 0, TA = 25°C
8.08
8.33
8.58
mV/G
BIN = 0 G, TA = 25°C
2.42
2.50
2.58
V
VCLP(H)init
–
VCC –
VSAT(H)
–
V
VCLP(L)init
–
VSAT(L)
–
V
TA = –40°C to 25°C
–
<±0.03
–
%/°C
TA = 25°C to 150°C
–
<±0.02
–
%/°C
TA = –40°C to 25°C
–
<±0.7
–
mV/°C
TA = 25°C to 150°C
–
<±0.1
–
mV/°C
Sens
VOUT(Q)
DSens
DVOUT(Q)
SIG_OFFSET = 0
11
G (gauss) = 0.1 mT (millitesla).
2Device performance is optimized for the input magnetic range of SENS_COARSE = 4 and input offset of SIG_OFFSET=0. If a different magnetic input range or signal
offset is required, please see the tables in the section EEPROM Customer-Programmable Parameter Reference, near the end of this document.
3Does not include drift over lifetime and package hysteresis.
4Offset drifts with temperature changes will be altered from the factory programmed values if Magnetic Input Signal Range is changed. If changes in Magnetic Input Signal
Range cannot be avoided because of application requirements, please contact Allegro for detailed information.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
6
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
A1340
PROGRAMMABLE CHARACTERISTICS: valid through full operating temperature range, TA , and supply voltage, VCC ,
CBYPASS = 10 nF, unless otherwise specified
Characteristics
Internal Bandwidth
Symbol
Test Conditions
Min.
Typ.
Max.
Unit1
–
2
–
bit
375
–
3000
Hz
TA = 25°C, measured as a percentage of BW
–
±5
–
%
QVO_FINE
–
12
–
bit
–1
–
+1
V
TA = 25°C, BIN = 0 G
–
1.22
–
mV
SENS_COARSE = 4, Measured at VCC = 5 V,
TA = 25°C
5
–
11.6
mV/G
SENS_MULT
–
12
–
bit
Programming2
Bandwidth Programming Bits
BW
Bandwidth Programming Range
BW
Bandwidth Post-Programming
Tolerance
∆BW
TA = 25°C; for programming values, see BW in
EEPROM Structure section
Fine Quiescent Voltage Output (QVO)2
Fine Quiescent Voltage Output
Programming Bits
Fine Quiescent Voltage Output
Programming Range
Fine Quiescent Voltage Output
Programming Step Size
QVO_FINE TA = 25°C, BIN = 0 G, VOUT(Q) = 2.5 V
StepQVO_
FINE
Output Sensitivity2
Output Sensitivity
SENS_OUT
Sensitivity Multiplier Programming Bits
Sensitivity Multipler Programming
Range
SENS_MULT TA = 25°C
0
–
2
–
Sensitivity Multiplier Programming
Step Size
StepSENS_
TA = 25°C
MULT
–
0.00048
–
–
–
33
–
data
sampling
point
LIN_x, programmed with output fitting method
–
12
–
bit
Output Polarity Bit
LIN_OUTPUT_INVERT
–
1
–
bit
Input Polarity Bit
LIN_INPUT_INVERT
–
1
–
bit
Linearization2
Linearization Positions
Linearization Position Coefficient Bits
LINPOS_
COEFF
Continued on the next page…
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
7
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
A1340
PROGRAMMABLE CHARACTERISTICS (continued): valid through full operating temperature range, TA , and supply volt-
age, VCC , CBYPASS = 10 nF, unless otherwise specified
Characteristics
Symbol
Temperature Compensation
Test Conditions
Min.
Typ.
Max.
Unit1
TC1_SENS_CLD, TA = –40°C
–
8
–
bit
TC1_SENS_HOT, TA = 150°C
(TC)2
1st Order Sensitivity TC Programming
Bits
–
8
–
bit
Typical 1st Order Sensitivity TC
Programming Range3
TC1_SENS_
CLD
TC1_SENS_
HOT
– 98
–
+291
m%/°C
Typical 1st Order Sensitivity TC
Programming Step Size3
StepTC1SENS
–
1.53
–
m%/°C
2nd Order Sensitivity TC Programming
Bits
Typical 2nd Order Sensitivity TC
Programming Range4
TC2_SENS_CLD, TA = –40°C
–
9
–
bit
TC2_SENS_HOT, TA = 150°C
–
9
–
bit
–1.53
–
+1.53
m%/°C2
–
0.00596
–
m%/°C2
–
8
–
bit
–122
–
+122
mG/°C
–
0.954
–
mG/°C
TC2_SENS_
CLD
TC2_SENS_
HOT
2nd Order Sensitivity TC Programming
StepTC2SENS
Step Size4
1st Order Magnetic Offset TC
Programming Bits
Typical 1st Order Magnetic Offset TC
Programming Range
1st Order Magnetic Offset TC Step
Size
TC1_OFFSET
TC1_OFFSET
StepTC1_
OFFSET
Output Clamping Range2
Clamp Programming Bits
Output Clamp Programming
Range5
Clamp Programming Step Size
CLAMP_HIGH
–
6
–
bit
CLAMP_LOW
–
6
–
bit
VCLP(H)
CLAMP_HIGH, measured as VOUT , TA = 25°C,
VCC = 5 V
2.54
–
VCC –
VSAT(H)
V
VCLP(L)
CLAMP_LOW, measured as VOUT , TA = 25°C,
VCC = 5 V
VSAT(L)
–
2.46
V
StepCLP(H) Measured as ΔVOUT , TA = 25°C
–
39
–
mV
StepCLP(L) Measured as ΔVOUT , TA = 25°C
–
39
–
mV
Continued on the next page…
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
8
A1340
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
PROGRAMMABLE CHARACTERISTICS (continued): valid through full operating temperature range, TA , and supply volt-
age, VCC , CBYPASS = 10 nF, unless otherwise specified
Characteristics
Symbol
Test Conditions
Min.
Typ.
Max.
Unit1
–1
–
1
%
–
<±1
–
%
–
±2
–
%
<±0.5
–
%
Accuracy
Linearity Sensitivity Error
LinERR
Sensitivity Drift Due to Package
Hysteresis
Variation on final programmed Sensitivity value;
∆SensPKG measured at TA = 25°C after temperature cycling
from 25°C to 150°C and back to 25°C
Sensitivity Drift Over Lifetime
∆SensLIFE
Ratiometry Quiescent Voltage
Output Error
RatVOUTQERR
Ratiometry Sensitivity Error
RatSENSERR
–
<±1
–
%
Ratiometry Clamp Error
RatCLPERR
–
<±1
–
%
TA = 25°C, shift after AEC Q100 grade 0
qualification testing
–
11
G (gauss) = 0.1 mT (millitesla).
by design.
unit m% / C means: (10–3 × %) / C.
4The unit m% / C2 means: (10–3 × %) / C2.
5Clamp_High minimum value trim can not be lower than QVO trim. Clamp_Low maximum value trim can not be higher than QVO trim.
2Determined
3The
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
9
A1340
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
Thermal Characteristics may require derating at maximum conditions
Characteristic
Symbol
Package Thermal Resistance
Test Conditions*
1-layer PCB with copper limited to solder pads
RθJA
Value
Units
174
ºC/W
*Additional thermal information available on Allegro website.
Power Dissipation versus Ambient Temperature
1100
Power Dissipation, PD (mW)
1000
900
800
1-layer PCB, Package KT
(RθJA = 174 C/W)
700
600
500
400
300
200
100
0
20
40
60
80
100
120
140
160
180
Temperature (°C)
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
10
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
A1340
CHARACTERISTIC PERFORMANCE
Average Supply Current (On) versus Temperature
12.0
12.0
11.6
11.6
11.2
TA (°C)
10.8
-40
10.4
0
-20
25
10.0
50
9.6
75
9.2
125
100
150
8.8
8.4
8.0
4.0
4.5
5.0
5.5
Supply Current, ICC(av) (mA)
Supply Current, ICC(av) (mA)
Average Supply Current versus Supply Voltage
VCC (V)
11.2
4.5
10.8
5.0
5.5
10.4
10.0
6.0
9.6
9.2
8.8
8.4
8.0
-60
-40
-20
Supply Voltage, VCC (V)
Output Saturation Voltage (Low) versus
Average Supply Voltage
40
60
80
100
120
140
160
300
250
TA (°C)
-40
-20
200
0
25
50
150
75
100
125
100
150
50
0
4.0
4.5
5.0
5.5
Output Saturation Voltage,
VSAT(L) (mV)
Output Saturation Voltage,
VSAT(L) (mV)
20
Output Saturation Voltage (Low) versus
Average Temperature
300
250
200
VCC (V)
4.5
150
5.0
5.5
100
50
0
-60
6.0
-40
Supply Voltage, VCC (V)
-20
200
0
25
50
150
75
100
125
100
150
50
Supply Voltage, VCC (V)
5.5
6.0
Output Saturation Voltage,
VSAT(H) (mV)
TA (°C)
-40
5.0
20
40
60
80
100
120
140
160
300
250
4.5
0
Output Saturation Voltage (High) versus
Average Temperature
300
0
4.0
-20
Ambient Temperature, TA (°C)
Output Saturation Voltage (High) versus
Average Supply Voltage
Output Saturation Voltage,
VSAT(H) (mV)
0
Ambient Temperature, TA (°C)
250
200
VCC (V)
4.5
150
5.0
5.5
100
50
0
-60
-40
-20
0
20
40
60
80
100
120
140
160
Ambient Temperature, TA (°C)
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
11
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
A1340
8.580
0.040
Average + 3 sigma
0.020
Average
0.010
0
-0.010
Average – 3 sigma
-0.020
-0.030
-0.040
-0.050
-80
Factory Programmed Sensitivity
versus Ambient Temperature
8.530
0.030
Sensitivity, Sens (mV/G)
Sensitivity Drift, ∆Sens (%/°C)
0.050
Factory Programmed Sensitivity Drift
versus Ambient Temperature
∆TA relative to TA = 25°C
-60
-40
-20
0
20
40
60
80
100
120
8.480
8.430
8.380
Average
8.280
8.230
Average – 3 sigma
8.180
8.130
8.080
-60
140
Average + 3 sigma
8.330
-40
Factory Programmed Quiescent Voltage Output
Drift versus Ambient Temperature
0.300
QVO, VOUT(Q) (V)
QVO (mV/°C)
40
60
80
100
120
140
160
2.580
Average + 3 sigma
Average
0.100
-0.200
-0.300
Average – 3 sigma
-0.500
∆TA relative to TA = 25°C
-60
-40
-20
0
20
40
60
80
100
2.540
Average + 3 sigma
2.520
2.500
2.460
2.440
120
2.420
-60
140
-40
-20
1.0
0.2
Average
VCC (V)
4.5
5.5
Average – 3 sigma
-2.0
-0.3
-20
-20
0
0
20
20
40
40
60
60
80
80
100
100
Ambient Temperature, TA (°C)
Ambient Temperature, TA (°C)
120
120
140
140
160
160
Linearity
(%) (%)
Sensitivity
Ratiometry
0.3
-40
-40
40
60
80
100
120
140
160
0.5
0.4
2.0
-0.1
-1.0
-0.2
20
Negative Linearity versus Ambient Temperature
Average Sensitivity Ratiometry
versus Ambient Temperature
3.0
0.5
Average + 3 sigma
0
Ambient Temperature, TA (°C)
Positive Linearity versus Ambient Temperature
Average Quiescent Voltage Output Ratiometry
versus Ambient Temperature
3.0
0.1
0
0
Average
Average – 3 sigma
2.480
Change in Ambient Temperature, ∆TA (°C)
QVO Linearity
Ratiometry
(%)(%)
20
2.560
0.500
-0.4
-3.0
-0.5-60
-60
0
Factory Programmed Quiescent Voltage Output
versus Ambient Temperature
0.700
-0.700
-80
-20
Ambient Temperature, TA (°C)
Change in Ambient Temperature, ∆TA (°C)
0.4
2.0
0.3
1.0
0.2
Average
Average + 3 sigma
0.1
0
0
VCC (V)
4.5
5.5
-0.1
-1.0
-0.2
Average – 3 sigma
-2.0
-0.3
-0.4
-3.0
-0.5-60
-60
-40
-40
-20
-20
0
0
20
20
40
40
60
60
80
80
100
100
Ambient Temperature, TA (°C)
Ambient Temperature, TA (°C)
120
120
140
140
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
160
160
12
2.560
Average + 3 sigma
0.300
Average
0.100
A1340
-0.200
-0.300
Average – 3 sigma
-0.500
-0.700
-80
QVO, VOUT(Q) (V)
QVO (mV/°C)
0.500
-40
-20
0
20
Average + 3 sigma
2.520
40
60
80
100
2.500
Average – 3 sigma
2.480
2.460
2.440
120
2.420
-60
140
-40
-20
Change in Ambient Temperature, ∆TA (°C)
0.5
0.4
0.4
0.3
0.2
VCC (V)
0.1
4.5
0
5.5
-0.1
-0.2
-0.3
-0.4
-20
0
20
40
60
80
100
Ambient Temperature, TA (°C)
120
140
160
Sensitivity Ratiometry (%)
QVO Ratiometry (%)
0.5
-40
0
20
40
60
80
100
120
140
160
Ambient Temperature, TA (°C)
Average Quiescent Voltage Output Ratiometry
versus Ambient Temperature
-0.5
-60
Average
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
∆TA relative to TA = 25°C
-60
2.540
Average Sensitivity Ratiometry
versus Ambient Temperature
0.3
0.2
VCC (V)
0.1
4.5
0
5.5
-0.1
-0.2
-0.3
-0.4
-0.5
-60
-40
-20
0
20
40
60
80
100
120
140
160
Ambient Temperature, TA (°C)
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
13
A1340
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
FUNCTIONAL DESCRIPTION
This section provides descriptions of the operating features
and subsystems of the A1340. For more information on specific terms, refer to the Definitions of Terms section. Tables of
EEPROM parameter values are provided in the EEPROM Structure section.
Signal Processing Parameter Setting
The A1340 has customer-programmable parameters that allow
the user to optimize the signal processing performed by the
A1340. Customer-programmable parameters apply to digital
signal processing (DSP) stage. Programmed settings are stored in
onboard EEPROM. The programming communication protocol is
described in the Programming Serial Interface section.
The initial analog processing is factory programmed to match
the application environment in terms of magnetic field range and
offset. This allows optimization of the electrical signal presented
to the DSP stage:
YAD (V) = SENS_COARSE (mV/G) × BIN
+ SIG_OFFSET (V) + VOUT(Q)(1)
where:
YAD is the output of the analog subsystem to the A-to-D converter,
BANDWIDTH SELECTION
The 3-dB bandwidth, BW , determines the frequency at which
the DSP function imports data from the analog front end A-to-D
convertor. It is programmed by setting the BW parameter in the
EEPROM. The values chosen for BW and RANGE affect the
DSP stage output resolution and the Response Time, tRESP . These
tradeoffs are represented in the Electrical Characteristics table,
above.
TEMPERATURE COMPENSATION
The magnetic properties of materials can be affected by changes
in temperature, even within the rated ambient operating temperature range, TA . Any change in the magnetic circuit due to temperature variation causes a proportional change in the device output.
The device can be compensated internally using the Temperature
Compensation (TC) circuitry. TC coefficients can be programmed
for Sensitivity and magnetic offset. The effect of temperature is
referred to as drift.
Table 1: Bandwidth-Related Tradeoffs
Bandwidth Selection, BW
(kHz)
SENS_COARSE is the factory-set coarse sensitivity,
BIN is the current magnetic input signal,
DSP Output Resolution
(bit)
0.375
12
1.500
11 to 12
3.000
10 to 11
SIG_OFFSET the factory-set signal offset, and
The DSP stage provides customer-programmable sensitivity
(gain) fine offset adjusting, TC processing, bandwidth, clamp,
and linearization selection.
Output is a digital voltage signal, proportional to the applied
magnetic signal.
Digital Signal Processing
The digitized analog signal is digitally processed to optimize
accuracy and resolution for conversion to the device output stage.
An advanced linearization feature also is available.
TC1_OFFSET (G/°C)
VOUT(Q) is the quiescent voltage output with no factory compensation.
QOUT
TC
1_O
FFS
ET
TC1_OFFSET Code 0
Min
Cod
e
TC
1_O
E
FFS
TM
ax
Cod
e
TA
Figure 2: The 1st Order Magnetic Offset Temperature
Compensation Coefficient (TC1_OFFSET)
TC1_OFFSET is used for linear adjustment of device output for temperature changes.
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115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
14
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
TC1_SENS(m%/C2)
For magnetic offset, compensation for 1st Order Magnetic Offset
TC, TC1_OFFSET , is a linear algorithm accounting for effects of
ambient temperature changes during device operation (see Figure 2). It can be programmed using the TC1_OFFSET parameter
in a range of ±122 mG/°C. This compensation is applied in DSP,
after bandwidth selection.
Sensitivity drift compensation is customer-programmed
(described below), within a framework of programmed temperature compensation. Optional temperature compensation for Sensitivity can be applied using built-in first-order and second-order
algorithms. Both approaches adjust the device gain in response
to input signal drift by adding or subtracting a value. The coefficients are programmed separately for temperatures above 25°C
and below 25°C, as shown in Table 2. The resulting functions are
illustrated in figure 4).
TC
25°C
1_S
EN
S_C
LD
Ma
TC1_SENS_CLD Code 0
TC
S_
1_SEN
CLD M
xC
TC
ode
in Cod
1_S
EN
H
S_
OT
Ma
xC
ode
TC1_SENS_HOT Code 0
e
TC1_SE
NS_HO
T Min C
ode
_S
EN
CL
DM
i n Co d e
e
EN
T C2 _S
T C2 _ S E
S_H
OT
x
Ma
TC2_SENS_HOT Code 0
NS _
HO
TM
in
C
e
2_
NS
L
_C
ax C od e
od
SE
TC2_SENS_CLD Code 0
DM
od
25°C
S_
C
T C2
TC1_SENS(m%/C2)
TA
TC
A1340
TA
Table 2: Sensitivity Temperature Compensation Options
Figure 4: Sensitivity TC Functions:
(upper) first order; (lower) second order
TA Range
< 25°C
> 25°C
1st Order
TC1_SENS_CLD
TC1_SENS_HOT
2nd Order
TC2_SENS_CLD
TC2_SENS_HOT
Sensitivity
Multiplier
/Fine QVO
Adjustment
TC Codes
Applied for
TA = 25°C
Output
Sensitivity
and Offset
Applied
Linearization
Linearization
Coefficients
Applied
Clamps
Are Set
Figure 3: Signal Path for Digital Subsystem
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115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
15
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
Either first-order or second-order, or both TC algorithms can
be applied. To apply an algorithm, select non-zero coefficients
for the corresponding EEPROM parameters (TC1_SENS_CLD
and TC1_SENS_HOT for first-order, TC2_SENS_CLD and
TC2_SENS_HOT for second order). If a method should not be
used, set the corresponding EEPROM parameter values to zero. If
both are selected, the A1340 applies the first-order, and then the
second-order algorithm during this stage.
The programmed values set the temperature compensation, YTC,
according to the following formula:
YTC (V) = YAD (V) + [ (TC1_SENS (m%/°C)
× ΔTA (°C)) + (TC2_SENS (m%/°C2) × ΔTA2 (°C)) ]
× ( YAD (V) – SIG_OFFSET (V) )
+ TC1_OFFSET (G/°C) × SENS_COARSE_COEF
× 5 (mV/G) × ΔTA (°C)
(2)
where:
YAD is the input from the analog subsystem via the A-to-D converter,
TC1_SENS is the first-order coefficient: either TC1_SENS_HOT
or TC1_SENS_CLD depending on TA ,
TC2_SENS is the second-order coefficient: either TC2_SENS_
HOT or TC2_SENS_CLD depending on TA ,
ΔTA is the change in ambient temperature from 25°C (for example: at 150°C, ΔTA = 150°C – 25°C = 125°C, or at –40°C,
ΔTA = –40°C – 25°C = –65°C), and
SIG_OFFSET (set to 0) is the factory programmed addition to the
magnetic offset parameter (sets the centerpoint of YAD ), and
SENS_COARSE_COEF = SENS_COARSE(code 0) /
SENS_COARSE(factory code) (sets the factory-programmed sensitivity of the YAD function).
DIGITAL OUTPUT SENSITIVITY (GAIN) ADJUSTMENT
Sensitivity is applied in the DSP subsystem, after bandwidth
selection and temperature compensation.
Note: If Sensitivity must be adjusted more than 20% from the
nominal value, please consider switching input magnetic range
for the optimization of A-to-D input.
OUTPUT FINE OFFSET ADJUSTMENT
The Fine Offset adjustment is the segment of the DSP signal used
to trim the device output, VOUT .
QVO_FINE is a customer-programmable parameter that sets the
Quiescent Voltage Output, VOUT(Q) , which is device output when
there is no significant applied magnetic field. The programmed
value sets the DSP output, YDA , taking into account the selected
Sensitivity:
YDA = SENS_MULT × YTC (V) + QVO_FINE (V)
(2)
SENS_OUT (mV/G) = SENS_MULT × SENS (mV/G) (3)
where SENS_MULT is the multiplication factor from 0.6 to 1.4.
QVO_FINE is set as a percentage of VOUT .
LINEARIZATION OF OUTPUT
Magnetic fields are not always linear throughout the full range
of target positions, such as in the case of ring magnet targets
rotated in front of a non-back-biased linear Hall sensor IC, shown
in Figure 5. The A1340 provides a programmable linearization
feature that allows adjustment of the transfer characteristic of the
device so that, as the actual position of the target changes, the
resulting changes in the applied magnetic field can be output as
corresponding linear increments.
Device Output (%)
A1340
100
90
80
70
60
50
40
30
20
10
0
-4
Initial Output
Linearized Output
-3
-2
-1
0
1
2
3
4
Ring Magnet Rotation (°)
Figure 5: Example of Linearization of a Sinusoidal Magnetic Signal Generated by a Rotating Ring Magnet
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
16
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
A1340
In order to achieve this, an initial set of linearization coefficients
has to be created. The user takes 33 samples of BIN: at the start
and at every 1/32 interval of the full input range. The user then
enters these 33 values into the Allegro ASEK programming utility
for the A1340, or an equivalent customer software program, and
generates coefficients corresponding to the values. The user then
uses the software load function to transmit the coefficients to the
EEPROM (LINPOS_COEFF parameter). The user then sets the
LIN_TABLE_DONE parameter to 1.
Each of the coefficient values can be individually overwritten
during normal operation. Figure 6 shows an example input-output
curve. The y axis represents the 32 equal full scale position
segments, and the x axis represents the the range of movement.
When the A1340 is in operation, it applies a linearization curve
built from the 33 coefficients provided by the user. For example,
at position 5 the device originally would output 384 LSB of magnetic field internal to device before the D-to-A converter. This
384 LSB is treated as input to the inverse linearization function,
after rescaling to the x axis as follows:
(384 – 128(offset)) × [32 / (3968(LSBmax)
– 128(LSBmin))] + 1 = 3.2
For x = 3.2, the inverse function will give output of 570 LSB
which is right on the curve of the linear output signal.
OUTPUT POLARITY
Device Output Polarity can be changed using the linearization
table, and the LIN_INPUT_INVERT and LIN_OUT_INVERT
bits.
In order to invert the device output polarity with no linearization, the linearization function must be set to gain 1 (linearization table coefficients are decimal values from 0 to 4096 with
steps of 128 codes), and one of the bits LIN_INPUT_INVERT or
LIN_OUT_INVERT must be set to 1.
4096
3968
3840
3712
3584
3456
Output Signal
3328
3200
Device Digital Output (LSBs)
3072
Input Signal
2944
2816
2688
2560
Linearization
Function
2432
2304
2176
2048
1920
1792
1664
(2) Rescaled x = 3.2,
yields LSB = 570
1536
1408
1280
1152
1024
896
768
640
(3) Final result is LSB = 570 for the input point 5
512
384
256
(1) x at 5, preprocessing LSB = 384
128
0
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33
Positions
Figure 6: Sample of Linearization Function Transfer Characteristic.
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17
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
A1340
If the goal is to change output polarity and apply linearization,
the output polarity should be changed by setting the gain of the
linearization function to 1 and setting the LIN_INPUT_INVERT
bit to 1. Then user can collect 33 points for linearization and
calculate the coefficients. After the coefficients are loaded
into the device, successful linearization will be applied by
leaving the LIN_INPUT_INVERT bit set to 1 and setting the
LIN_TABLE _DONE bit to 1.
OUTPUT SIGNAL CLAMPS SETTING
To eliminate the effects of outlier points, the A1340 Clamp
Range, VCLP , is initially set to a high limit of VCC – Vsat for high
clamp and 0 V + Vsat for low clamp, and can be adjusted using
the CLAMP_HIGH and CLAMP_LOW parameters.
PROTECTION FEATURES
Lockout and clamping features protect the A1340 internal circuitry and prevent spurious output when supply voltage is out of
specification. Open circuit detection is also provided.
Operating Undervoltage Lockout
Lockout features protect the A1340 internal circuitry and prevent
spurious output when VCC is out of specification. Diagnostic
circuitry reuses the output pin (VOUT) to provide feedback to
the external controller. The A1340 provides lockout protection
for undervoltage on the supply line. Lockout features protect the
A1340 internal circuitry and prevent spurious output when VCC
is out of specification. Diagnostic circuitry reuses the output pin
(VOUT) to provide feedback to the external controller.
If the supply voltage drops below VCC(UV_low) the device internal lockout function isolates the onboard processing circuits and
pulls the VOUT pin to a diagnostic level. As the supply voltage
rises above VCC(UV_high) the diagnostic condition is removed.
Open Circuit Detection
Diagnostic circuitry reuses the output pin (VOUT) to provide
feedback to the external controller if a resistor, ROCD , is placed
between VOUT and a separate VBAT or ground reference, as
shown in table 3. When an open circuit occurs on any combination of A1340 pins, a corresponding VOUT level is generated.
TYPICAL APPLICATION
Multiple A1340 linear devices can be connected to the external
controller as shown in Figure 7. However, EEPROM programming in the A1340 occurs when the external control unit excites
the A1340 VOUT pin by EEPROM pulses generated by the ECU.
Whichever A1340s are excited by EEPROM pulses on their
VOUT pin will accept commands from the controller.
Table 3: Open Circuit Diagnostic Truth Table
Node A
Node B
Node C
VOUT State
Open
Closed
Closed
Closed
0 V to VBAT
Open
Closed
VOUT(Q)
Open
Open
Closed
GND
Open
Closed
Open
VBAT
Closed
Open
Open
VCC
Closed
Closed
Open
VCC to VBAT
Closed
Open
Closed
VOUT(Q)
Closed
Closed
Open
0 V to VCC
Closed
Open
Open
VCC
Open
Open
Closed
GND
Open
Closed
Open
GND
Open
Closed
Closed
GND
VCC1
VBAT Referenced
VBAT
VCC
A
VCC
A1340
B
ROCD
VOUT
GND
C
0.01 µF
VCC
A1340
VOUT
OUT1
GND
ECU
VCC2
Ground Referenced
VCC
A
VCC
A1340
VOUT
GND
C
ROCD
B
0.01 µF
VCC
A1340
VOUT
OUT2
GND
Figure 7: Typical Application with Multiple A1340s
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115 Northeast Cutoff
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18
A1340
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
PROGRAMMING SERIAL INTERFACE
The A1340 incorporates a serial interface that allows an external
controller to read and write registers in the A1340 EEPROM and
volatile memory. The A1340 uses a point-to-point communication
protocol, based on Manchester encoding per G. E. Thomas (a rising edge indicates 0 and a falling edge indicates 1), with address
and data transmitted MSB first.
Transaction Types
Each transaction is initiated by a command from the controller;
the A1340 does not initiate any transactions. Two commands are
recognized by the A1340: Write and Read. There also are three
special function Write commands: Write Access Code, Write Disable Output, and Write Enable Output. One response frame type
is generated by the A1340, Read Acknowledge.
If the command is Read, the A1340 responds by transmitting the
requested data in a Read Acknowledge frame. If the command is
any other type, the A1340 does not acknowledge.
As shown in Figure 8, The A1340 receives all commands via the
VCC pin. It responds to Read commands via the VOUT pin. This
implementation of Manchester encoding requires the communication pulses be within a high (VMAN(H)) and low (VMAN(L))
range of voltages for the VCC line and the VOUT line. The Write
command pulses to EEPROM are supported by two high voltage
pulses on the VOUT line.
Writing the Access Code
If the external controller will write to or read from the A1340
memory during the current session, it must establish serial communication with the A1340 by sending a Write command including the Access Code within 70 ms after powering up the A1340. If
this deadline is missed, all write and read access is disabled until
the next power-up.
Writing to Non-Volatile EEPROM
When a Write command requires writing to non-volatile
EEPROM (all standard Writes), after the Write command the
controller must also send two Programming pulses, well-separated, long high-voltage strobes via the VOUT pin. These strobes
are detected internally, allowing the A1340 to boost the voltage
on the EEPROM gates.
To ensure these strobes are properly received, the controller must
suppress the normal device output on the VOUT pin (that is, the
linear output voltage in response to magnetic field input). To do
so, the external controller sends a Write Disable Output command
before transmitting the strobes. This puts the VOUT pin into a
high impedance state. After writing is complete, the controller
must send an Write Enable Output command to restore VOUT to
normal operation. The required sequence is shown in Figure 9.
Write/Read Command –
Manchester Code
ECU
High Voltage pulses to
activate EEPROM cells
VCC
A1340
VOUT
GND
Read Acknowledge
– Manchester Code
Figure 8: Top-Level Programming Interface
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
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19
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
A1340
Writing to Volatile Registers
Writing to the volatile register 0x24 is done for Write Access
Code, Write Disable Output, and Write Enable Output commands. This requires the external controller to send the Write
command on the VCC pin. Successive Write commands to volatile memory must be separated by tWRITE . The required sequence
is shown in Figure 9.
Reading from EEPROM
For proper reading from the A1340, it is recommended that the
output be disabled before a Read command is sent. Otherwise
the external controller may continue to track the magnetic field
input until the first edge of the Read Acknowledge frame. In that
case the controller would be required to distinguish between the
output associated with the magnetic field and the response to the
Read command.
To disable output, the external controller sends a Write Disable
Output command before transmitting the Read command. This
puts the VOUT pin into a high impedance state. After writing
is complete, the controller must send a Write Enable Output
command to restore VOUT to normal operation. After the Read
VCC
Write Access
Command
Disable Output
Command
Write to
EEPROM
VOUT
Acknowledge frame has been received from the A1340, the
controller must send a Write Enable Output command to restore
VOUT to normal operation. The required sequence is shown in
Figure 9.
Error Checking
The serial interface uses a cyclic redundancy check (CRC) for
data-bit error checking (synchronization bits are ignored during
the check).
The CRC algorithm is based on the polynomial
g(x) = x3 + x + 1 ,
and the calculation is represented graphically in Figure 10.
The trailing 3 bits of a message frame comprise the CRC token.
The CRC is initialized at 111.
C0
C1
1x 0
1x 1
0x 2
1x 3
= x3 + x + 1
Figure 10: CRC Calculation
Write
Command
EEPROM
Programming
Pulses
Enable Output
Command
High
Impedance
High
Impedance
Normal Operation
Input Data
C2
Normal Operation
GND
<70 ms from power-on
Write to
Volatile Memory
(Register 0x24)
VCC
Read from
EEPROM
Write Access
Command
tsPULSE(E) tWRITE(E)
Previous
Command
Write Access
Command
<70 ms from
power-on
VCC
t
tDIS_OUT
Write
Command
tWRITE
tWRITE
Disable Output
Command
tENB_OUT
Next
Command
t
tWRITE
Read
Command
Enable Output
Command
<70 ms from power-on
VOUT
High
Impedance
Normal Operation
Read
Acknowledge
High
Impedance
Normal Operation
GND
t
tDIS_OUT
tSTART_READ
tSTART_READ
tENB_OUT
Figure 9: Programming Read and Write Timing Diagrams
(see Serial Interface Reference section for definitions)
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115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
20
A1340
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
Serial Interface Reference
Table 4: Serial Interface Protocol Characteristics1
Characteristics
Symbol
Note
Min.
Typ.
Max.
Unit
Customer Access Code should be fully entered
in less than tACC , measured from when VCC
crosses VCC(UV_high).
–
–
70
ms
Defined by the input message bit rate sent from
the external controller
5
–
100
kbps
Input/Output Signal Timing
Access code Time Out
tacc
Baud Rate
Bit Time
tBIT
Data bit pulse width at 5 kbps
195
200
205
µs
Data bit pulse width at 100 kbps
9.5
10
10.5
µs
–11
–
+11
%
Bit Time Error
errTBIT
Deviation in tBIT during one command frame
Volatile Memory Write Delay
tWRITE
Required delay from the trailing edge of certain
Write command frames to the leading edge of a
following command frame
2 × tBIT
–
–
µs
Required delay from the trailing edge of the
second EEPROM Programming pulse to the
leading edge of a following command frame
2 × tBIT
–
–
µs
Required delay from the trailing edge of a Read
Acknowledge frame to the leading edge of a
following command frame
2 × tBIT
–
–
µs
Delay from the trailing edge of a Read
tSTART_READ command frame to the leading edge of the Read
Acknowledge frame
25 µs –
0.25 × tBIT
50 µs –
0.25 × tBIT
150 µs –
0.25 × tBIT
µs
Non-Volatile Memory Write Delay
Read Acknowledge Delay
Read Delay2
tWRITE(E)
tREAD
Disable Output Delay2
tDIS_OUT
Delay from the trailing edge of a Disable Output
command frame to the device output going from
normal operation to the high impedance state
1 µs –
0.25 × tBIT
5 µs –
0.25 × tBIT
15 µs –
0.25 × tBIT
µs
Enable Output Delay2
tENB_OUT
Delay from the trailing edge of an Enable Output
command frame to the device output going from
the high impedance state to normal operation
1 µs –
0.25 × tBIT
5 µs –
0.25 × tBIT
15 µs –
0.25 × tBIT
µs
tsPULSE(E)
Delay from last edge of write command to start
of EEPROM programming pulse
40
–
–
μs
Applied to VCC line
7.3
–
–
V
VCC –
VSAT(H)
–
–
V
EEPROM Programming Pulse
EEPROM Programming Pulse
Setup Time
Input/Output Signal Voltage
Manchester Code High Voltage
VMAN(H)
Manchester Code Low Voltage
VMAN(L)
Read from VOUT line
Applied to VCC line
–
–
5.7
V
Read from VOUT line
–
–
VSAT(L)
V
1Determined
by design.
2In the case where a slower baud rate is used, the output responds before the transfer of the last bit in the command message is completed.
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115 Northeast Cutoff
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21
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
A1340
Serial Interface Message Structure
The general format of a command message frame is shown in
Figure 11. Note that, in the Manchester coding used, a bit value
of 1 is indicated by a falling edge within the bit boundary, and
a bit value of zero is indicated by a rising edge within the bit
boundary.
Read/Write
Synchronize
0
Memory Address
Data
0 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1
MSB
...
CRC
0/1 0/1 0/1 0/1
MSB
The bits are described in Table 5.
Manchester Code per G. E. Thomas
0 0 1 1 0
Bit boundaries
Figure 11: General Format for Serial Interface
Commands
Table 5: Serial Interface Command General Format
Quantity
of Bits
Parameter Name
Values
2
Synchronization
00
Used to identify the beginning of a serial interface command
1
Read/Write
0
[As required] Write operation
1
[As required] Read operation
Description
6
Address
0/1
[Read/Write] Register address (volatile memory or EEPROM)
Variable
Data
0/1
[As required] 30 bits of data
3
CRC
0/1
Incorrect value indicates errors
Allegro MicroSystems, LLC
115 Northeast Cutoff
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22
A1340
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
The following command messages can be exchanged between the
device and the external controller:
•
•
•
•
•
•
Read
Read Acknowledge
Write
Write Access Code
Write Disable Output
Write Enable Output
For EEPROM address information, refer to the EEPROM
Structure section.
READ
Function
Provides the address in A1340 memory to be accessed to transmit the contents to the external controller in the next
Read Acknowledge command.
A timely Write Access Code command is required once, at power-up of the A1340.
Syntax
Sent by the external controller on the A1340 VCC pin.
Sent after a Write Disable Output command.
Related Commands
Read Acknowledge
Read/Write
Memory Address
Synchronize
Pulse Sequence
0
0
CRC
1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1
MSB
Options
None
Examples
Address in non-volatile memory: 0XXXXX
Address in volatile memory: 100100 (Register 0x24)
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115 Northeast Cutoff
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23
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
A1340
READ ACKNOWLEDGE
Function
Transmits to the external controller data retrieved from the A1340 memory in response to the most recent Read
command.
Syntax
Sent by the A1340 on the A1340 VOUT pin.
Sent after a Read command and before a Write Enable Output command.
Related Commands
Read
Data
(30 bits)
Synchronize
Pulse Sequence
0
CRC
0/1 0/1 0/1 0/1 . . . 0/1 0/1 0/1 0/1 0/1
0
MSB
Options
If EEPROM Error Checking and Correction (ECC) is not disabled by factory programming, the 6 MSBs are EEPROM
data error checking bits. Refer to the EEPROM Structure section for more information.
Examples
–
WRITE
Function
Transmits to the A1340 data prepared by the external controller.
Syntax
Sent by the external controller on the A1340 VCC pin.
A timely Write Access Code command is required once, at power-up of the A1340.
For writing to non-volatile memory: Sent after a Write Disable Output command.
Related Commands
Disable Output, Enable Output, Write Access Code
Read/Write
Synchronize
Pulse Sequence
0
0
Data
(30 bits)
Memory Address
0 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 . . .
MSB
Options
–
Examples
Address in non-volatile memory: 0XXXXX
Address in volatile memory: 100100 (Register 0x24)
CRC
0/1 0/1 0/1 0/1
MSB
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115 Northeast Cutoff
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24
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
A1340
WRITE ACCESS CODE
Function
Transmits the Access Code to the A1340; data prepared by the external controller, but must match the internal 30-bit
code in the A1340 memory.
Syntax
Sent by the external controller on the A1340 VCC pin.
Sent within 70 ms of A1340 power-on, and before any other command.
Related Commands
Read/Write
Pulse Sequence
0
Data
(30 bits)
Memory Address
Synchronize
0
0
1
0
0
1
0
0
MSB
1
0 ...
0
CRC
1
0
0
1
MSB
Options
None
Examples
Standard Customer Access Code: 0x2781_1F77 to address 0x24
WRITE DISABLE OUTPUT
Function
Suppresses normal output from the VOUT pin to allow clear transmission of Read Acknowledge commands and
EEPROM Programming pulses. Places VOUT in a high impedance state.
Syntax
Sent by the external controller on the A1340 VCC pin.
For writing to non-volatile memory: Sent before each Write command.
For reading: Sent before a Read command.
Related Commands
Write Enable Output
Read/Write
Pulse Sequence
0
0
0
1
MSB
Options
None
Examples
0x10 to address 0x24
Data
(30 bits)
Memory Address
Synchronize
0
0
1
0
0
0 ...
0
1
CRC
0
0
0
0
0
1
0
MSB
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
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25
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
A1340
WRITE ENABLE OUTPUT
Function
Restores normal output from the VOUT pin after a high impedance state has been imposed by a Disable Output
command.
Syntax
Sent by the external controller on the A1340 VCC pin.
For writing to non-volatile memory: Sent after a Write command and corresponding EEPROM Programming pulses.
For reading: Sent after a Read Acknowledge command.
Related Commands
Write Disable Output
Read/Write
Pulse Sequence
0
0
0
1
MSB
Options
None
Examples
0x0 to address 0x24
Data
(30 bits)
Memory Address
Synchronize
0
0
1
0
0
0 ...
0
0
CRC
0
0
0
0
0
1
1
MSB
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
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26
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
A1340
EEPROM STRUCTURE
Programmable values are stored in an onboard EEPROM,
including both volatile and non-volatile registers. Although it is
separate from the digital subsystem, it is accessed by the digital
subsystem EEPROM Controller module.
EEPROM Bit
Contents
29
28
27
26
25
24
23
The EEPROM is organized as 30-bit wide words, and by default
each word has 24 data bits and 6 ECC (Error Checking and Correction) check bits, stored as shown in Figure 12.
22
21
20
19
18
17
D23 D22 D21 D20 D19 D18 D17 D16 D15 D14 D13 D12 D11
16
15
C5
D10
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
D9
D8
D7
D6
D5
D4
C4
D3
D2
D1
C3
D0
C2
C1
C0
Figure 12: EEPROM Word Bit Sequence; C# – Check Bit, D# – Data Bit
Allegro MicroSystems, LLC
115 Northeast Cutoff
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27
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
A1340
Table 6: EEPROM Register Map of Customer-Programmable Parameters (Non-Volatile Memory)
Address
Bits
Parameter Name
Description
DAC profile
0x08
23:15
TC2_SENS_HOT
2nd
Order Sensitivity Temperature Coefficient, ΔT (from 25°C) > 0
Two’s complement
0x08
14:6
TC2_SENS_CLD
2nd Order Sensitivity Temperature Coefficient, ΔT (from 25°C) < 0
Two’s complement
0x08
5:2
SENS_COARSE
Factory Adjustment of the Magnetic Input Signal Range
Non-uniform
0x08
1:0
BW
Internal Bandwidth
Non-uniform
0x09
23:16
TC1_SENS_HOT
1st
Order Sensitivity Temperature Coefficient, ΔT (from 25°C) > 0
Non-uniform
0x09
15:8
TC1_SENS_CLD
1st Order Sensitivity Temperature Coefficient, ΔT (from 25°C) < 0
Non-uniform
0x09
7:0
TC1_OFFSET
1st
0x0A
23:12
SCRATCH_C
Customer Scratchpad
0x0A
11:0
SENS_MULT
Output Sensitivity/ Sensitivity Multiplier
0x0B to 0x1A
23:12
LINPOS_COEFF
Linearization Coefficients (odd-numbered sampling positions)
(LIN_1, LIN_3, ..., LIN_31)
0x0B to 0x1B
11:0
LINPOS_COEFF
Linearization Coefficients (even-numbered sampling positions)
(LIN_0, LIN_2, ..., LIN_32)
0x1B
23
LIN_TABLE_DONE
0x1B
22
LIN_OUTPUT_INVERT
0x1B
21
LIN_INPUT_INVERT
0x1B
20:12
ID
0x1C
23:18
CLAMP_HIGH
0x1C
17:12
CLAMP_LOW
0x1C
11
EEPROM_LOCK1
0x1C
10
Reserved
0x1C
9
OPEN_DRAIN
0x1C
8:4
SIG_OFFSET
Order Magnetic Offset Drift Compensation
Two’s complement
Linearization Complete Flag
Linearization Output Polarity Inversion
Linearization Input Polarity Inversion
Customer Identification Number
Clamp Upper Limit
Clamp Lower Limit
Customer EEPROM Lock
Reserved for system use (customer should not write this bit)
Disable Internal Pullups on Digital Output Signals
Factory Adjustment of Input Signal Offset
Two’s complement
0x1C
3:2
Reserved
Reserved for System Use (bits written here will not affect device
performance)
0x1C
1
Reserved
Reserved for system use (customer should not write this bit)
0x1C
0
Reserved
Reserved for system use (customer should not write this bit)
0x1D
23:12
SCRATCH_C
0x1D
11:0
QVO_FINE
Customer Scratchpad
Fine Quiescent Voltage Output (QVO)
Two’s complement
1Customer
EEPROM lock allows the customer to lock the EEPROM registers from any further changes for the life of the device. Memory reading is still possible after the
EEPROM lock bit is set. In the case that a write command is sent to the device by accident after the EEPROM lock, the device needs to be repowered to be accessible
again for memory read.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
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28
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
A1340
EEPROM Customer-Programmable Parameter Reference
BW (Register Address: 0x08, bits 1:0)
Function
Filter Bandwidth
Selects the filter bandwidth (3-dB frequency) for the digitized applied magnetic field signal, applied when passed to
the digital system after analog front-end processing.
Syntax
Quantity of bits: 2
Related Commands
–
Values
00: 1500 Hz (Default)
01: (Factory use only)
10: 375 Hz
11: 3000 Hz
Options
–
Examples
–
CLAMP_HIGH (Register Address: 0x1C, bits 23:18)
Function
Clamp Upper Limit
Sets the maximum valid output value.
Syntax
Quantity of bits: 6
Related Commands
CLAMP_LOW
Values
000000: 5 V – Vsat (Default)
111111: 2.5 V for VCC = 5 V
Options
The default, VCLP(H)init , is used if this parameter is not set.
Examples
When ratiometry is on (RATIOM_OFF = 0): Range is VCC / 2, up to VCC – Vsat.
When ratiometry is off (RATIOM_OFF = 1): Typical value is VCC – 0.5 × VCC
× (CLAMP_HIGH / 64)
Allegro MicroSystems, LLC
115 Northeast Cutoff
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29
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
A1340
CLAMP_LOW (Register Address: 0x1C, bits 17:12)
Function
Clamp Lower Limit
Sets the minimum valid output value.
Syntax
Quantity of bits: 6
Related Commands
CLAMP_HIGH
Values
000000: 0 V + Vsat (Default)
111111: 2.5 V for VCC = 5 V
Options
The default, VCLP(L)init , is used if this parameter is not set.
Examples
When ratiometry is on (RATIOM_OFF = 0): Range is VCC / 2, down to Vsat.
When ratiometry is off (RATIOM_OFF = 1): Typical value is 0 V + 0.5 × VCC
× (CLAMP_LOW / 64)
ID (Register Address: 0x1B, bits 20:12)
Function
Customer Identification Number
Available register for identifying the A1340 for multiple-unit applications.
Syntax
Quantity of bits: 12
Related Commands
SCRATCH_C
Values
Free-form
Options
–
Examples
–
LIN_INPUT_INVERT (Register Address: 0x1B, bit 21)
Function
Inverts the polarity of the input signal before it is sent into the linearization block. This
setting is effective only if LIN_TABLE_DONE is set to 1.
Syntax
Quantity of bits: 1
Related Commands
LIN_x, LIN_OUTPUT_INVERT
Values
0: No inversion of signal before input into the linearization block.
1: Input signal inverted before it is sent into the linearization block.
Options
–
Examples
–
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
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30
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
A1340
LIN_OUTPUT_INVERT (Register Address: 0x1B, bit 22)
Function
Inverts the polarity of the input signal after the linearization block. This setting is effective only if LIN_TABLE_DONE
is set to 1.
Syntax
Quantity of bits: 1
Related Commands
LIN_x, LIN_INPUT_INVERT
Values
0: No inversion of signal after processing in the linearization block.
1: Input signal inverted after processing in the linearization block.
Options
–
Examples
–
LINPOS_COEFF
(LIN_0, LIN_2, ..., LIN_32) (Register Address: 0x0B to 0x1B, bits 11:0)
(LIN_1, LIN_3, ..., LIN_31) (Register Address: 0x0B to 0x1A, bits 23:12)
Function
Linearization Coefficients
These addresses are available to store customer-generated and loaded coefficients used for linearization of the
temperature-compensated and offset digital signal. Note: These are not used by the device unless the LIN_TABLE_
DONE bit is set.
Syntax
Quantity of bits: 12 (each)
LIN_x corresponds to Input Sample BINx
Coefficient data stored in two’s complement format
Values must be monotonically increasing
Related Commands
LIN_INPUT_INVERT, LIN_OUTPUT_INVERT, LIN_TABLE_DONE
Values
Calculated according to applied magnetic field
Input
Sample
Options
Examples
Output
Position
BIN0
−2048
EEPROM
Address
Bits
Input
Sample
0x0B
11:00
BIN16
Output
Position
EEPROM
Address
Bits
0
0x13
11:00
BIN1
−1920
0x0B
23:12
BIN17
128
0x13
23:12
BIN2
−1792
0x0C
11:00
BIN18
256
0x14
11:00
BIN3
−1664
0x0C
23:12
BIN19
384
0x14
23:12
BIN4
−1536
0x0D
11:00
BIN20
512
0x15
11:00
BIN5
−1408
0x0D
23:12
BIN21
640
0x15
23:12
BIN6
−1280
0x0E
11:00
BIN22
768
0x16
11:00
BIN7
−1152
0x0E
23:12
BIN23
896
0x16
23:12
BIN8
−1024
0x0F
11:00
BIN24
1024
0x17
11:00
BIN9
−896
0x0F
23:12
BIN25
1152
0x17
23:12
BIN10
−768
0x10
11:00
BIN26
1280
0x18
11:00
BIN11
−640
0x10
23:12
BIN27
1408
0x18
23:12
BIN12
−512
0x11
11:00
BIN28
1536
0x19
11:00
BIN13
−384
0x11
23:12
BIN29
1664
0x19
23:12
BIN14
−256
0x12
11:00
BIN30
1792
0x1A
11:00
BIN15
−128
0x12
23:12
BIN31
1920
0x1A
23:12
BIN32
2047
0x1B
11:00
–
Allegro MicroSystems, LLC
115 Northeast Cutoff
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1.508.853.5000; www.allegromicro.com
31
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
A1340
LIN_TABLE_DONE (Register Address: 0x1B, bit 23)
Function
Linearization Table Loaded
Set by the customer to indicate custom coefficients have been loaded (into the LINPOS_COEFF area of EEPROM).
When this flag is set, the device uses the customer coefficients for output linearization. Allows correction for targets
that generate non-linear magnetic fields.
Syntax
Quantity of bits: 1
Related Commands
LINPOS_COEFF
Values
Options
–
Examples
–
0: Linearization algorithm applies default coefficients to the processed signal (Default)
1: Linearization algorithm applies customer-loaded coefficients to the processed signal
OPEN_DRAIN (Register Address: 0x1C, bit 9:0)
Function
Output Digital Signal Pullup Disable
Switches off internal pullup resistors when digital serial data is being transmitted and uses customer pullup. (Does
not affect transmission of normal magnetic data transmission).
Syntax
Quantity of bits: 1
Related Commands
–
Values
Options
–
Examples
–
0: Internal output pullup enabled at all times (Default)
1: Disable internal output pullup during transmission of digital serial data
QVO_FINE (Register Address: 0x1D, bits 11:0)
Function
Quiescent Voltage Output (QVO)
Adjusts the device normal output (voltage response to applied magnetic field) to set the baseline output level: for a
quiescent applied magnetic field (BIN ≈ 0 G).
Syntax
Quantity of bits: 12
Code stored in two’s complement format
Related Commands
SIG_OFFSET
Values
Options
The default, VOUT(Q) , is used if this parameter is not set.
Examples
–
0111 1111 1111: +49.98% of output full scale range (Default)
1000 0000 0000: –50% of output full scale range
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
32
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
A1340
RATIOM_OFF (Register Address: 0x1C, bit 11)
Function
Output Ratiometry Disable
Syntax
Quantity of bits: 1
Related Commands
–
Values
0: Ratiometry enabled (Default)
The output is determined by:
VOUT = 0.5 × VCC × [(BIN / RANGE (G))+1]
1: Ratiometry disabled
The output is determined by:
VOUT = 2.5 (V) × [(BIN / RANGE (G))+1]
RANGE defined in SENS_COARSE table below.
Options
–
Examples
–
SCRATCH_C (Register Address: 0x1D, bits 23:12)
Function
Customer Scratchpad
For optional customer use in storing values in the device.
Syntax
Quantity of bits: 12
Related Commands
ID
Values
Free-form field
Options
–
Examples
–
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
33
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
A1340
SENS_COARSE (Register Address: 0x08, bits 5:2)
Note: If the Coarse Sensitivity is changed, the offset drifts with temperature changes will be altered from the factory programmed values. If
changing Coarse Sensitivity cannot be avoided because of application requirements, please contact Allegro for detailed information.
Function
Coarse Sensitivity
Sets the nominal (coarse) sensitivity of the device, SENS_COARSE, which can be defined as ΔVOUT / ΔBIN .
Selection determines the RANGE, the extent of the applied magnetic flux intensity, BIN , sampled for signal
processing. (Use SIG_OFFSET to adjust the BIN level at which RANGE is centered.)
Syntax
Quantity of bits: 4
Related Commands
SIG_OFFSET, SENS_OUT
Coarse Sensitivity at VCC = 5 V
(Typical)
(mV/G)
RANGE
(G)
0000 (Default)
0001
0010
0011
0100
0101
0110
0111
5.00
16.70
12.50
10.00
8.30
6.25
4.00
3.30
±500
±150
±200
±250
±300
±400
±625
±750
1000
1001
1010
1011
1100
1101
1110
1111
2.80
2.50
2.00
1.67
1.43
1.25
25.00
1.11
±875
±1000
±1250
±1500
±1750
±2000
±100
±2250
Code
Values
Options
–
Examples
To set a sampled BIN range of 500 G, set RANGE = ±250 G (SENS_COARSE = 0011). That would also set Coarse
Sensitivity to 10 mV/G (SENS_COARSE = 0011).
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
34
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
A1340
SENS_MULT (Register Address: 0x0A, bits 11:0)
Function
Sensitivity Multiplier
After temperature compensation, establishes the gain of the device in normal output (response to a change in the
applied magnetic field) by indicating a multiplier value.
Quantity of bits: 12
2.0
SENS_MULT 1.0
Value
Syntax
0
0
0x800
0xFFF
SENS_MULT
Programming Code
Related Commands
RANGE, TC1_SENS_CLD, TC1_SENS_HOT, TC2_SENS_CLD, TC2_SENS_HOT
Values
RANGE: ±300 G
SENS_COARSE: 8.33 mV/G
Options
SENS_OUT = SENS_COARSE, that is, SENS_MULT = 1 (code 0) if this parameter is not set.
Examples
–
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
35
A1340
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
SIG_OFFSET (Register Address: 0x1C, bits 8:4)
Note: If changing Coarse Magnetic Offset cannot be avoided because of application requirements, please contact Allegro for detailed information.
Function
Magnetic Offset Compensation (Coarse)
Adjusts the center of the selected RANGE to adapt to the application magnetic field.
(The applied offset, QVO_COARSE, is the sum of the selected SIG_OFFSET and a VOUT(Q) factor that compensates
for the magnetic back-biasing of the device.)
The offset values are expressed in terms of a percentage of the full scale of the selected RANGE and as a voltage
relative to VOUT(Q).
Note: This is an analog domain variable, so step size is variable, and the offset values shown here represent the
expected typical value for the programmed code.
Syntax
Quantity of bits: 5
Code stored in two’s complement format.
Related Commands
RANGE, TC1_OFFSET
SIG_OFFSET
(% of Full-Scale RANGE)
SIG_OFFSET
(Typical)
(ΔV)
00000 (Default)
00001
00010
00011
00100
00101
00110
00111
0.00
6.25
12.50
18.75
25.00
31.25
37.50
43.75
0.00
0.31
0.63
0.94
1.25
1.56
1.88
2.19
01000
01001
01010
01011
01100
01101
01110
01111
50.00
56.25
62.75
68.75
75.00
81.25
87.50
93.75
2.50
2.81
3.13
3.44
3.75
4.06
4.38
4.69
10000
10001
10010
10011
10100
10101
10110
10111
–100.00
–93.75
–87.50
–81.25
–75.00
–68.75
–62.50
–56.25
–5.00
–4.69
–4.38
–4.06
–3.75
–3.44
–3.13
–2.81
11000
11001
11010
11011
11100
11101
11110
11111
–50.00
–43.75
–37.50
–31.25
–25.00
–18.75
–12.50
–6.25
–2.50
–2.19
–1.88
–1.56
–1.25
–0.94
–0.63
–0.31
Code
Values
Options
The default, VOUT(Q) , is used if this parameter is not set.
Examples
To set the input range from 0 to 1000 G, with a centerpoint at +500 G:
1. If SENS_COARSE at 5 mV/G (SENS_COARSE code = 0000). This establishes a full scale input RANGE of 1000
G.
2. The full scale input value, 1000 G, is used as the start point of the offset, so:
SIG_Offset = (Centerpoint – Full scale input) / Full scale input
= 100 × (500 – 1000) / 1000 = –50%
3. Set the SIG_OFFSET code to 11000 (24), to select SIG_OFFSET = –50%.
This also has the effect of setting SIG_OFFSET = –2.5 V.
Allegro MicroSystems, LLC
115 Northeast Cutoff
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36
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
A1340
TC1_OFFSET (Register Address: 0x09, bits 7:0)
Function
1st Order Magnetic Offset Temperature Compensation coefficient.
Syntax
Quantity of bits: 8
Code stored in two’s complement format.
Related Commands
SIG_OFFSET, TC1_SENS_CLD, TC1_SENS_HOT, TC2_SENS_CLD, TC2_SENS_HOT
Values
Options
No fine magnetic offset is applied if this parameter is not set.
Examples
–
0111 1111: +122 mG/°C
1000 0000: –122 mG/°C
TC1_SENS_CLD (Register Address: 0x09, bits 15:8)
TC1_SENS_HOT (Register Address: 0x09, bits 23:16)
Function
1st Order Sensitivity Temperature Coefficient.
Specifies a compensation factor for drift in device Sensitivity resulting from changes in ambient temperature during
operation. Applies a 1st order, linear compensation algorithm. Two different parameters are set, one for increasing
values relative to TA = 25°C, and the other for decreasing values, as follows:
• TC1_SENS_HOT: ΔTA (from 25°C) > 0
• TC1_SENS_CLD: ΔTA (from 25°C) < 0
Syntax
Quantity of bits: 8 (each parameter)
Related Commands
SENS_MULT, TC2_SENS_HOT, TC2_SENS_CLD
Values
1100 0000: –98 m% / °C
1011 1111: +291 m% / °C
Increments (step size) of ±1.53 m% / °C
Options
Set all bits to 0 if TC1_SENS_HOT and TC1_SENS_CLD are not used.
Examples
Refer to Temperature Compensation section.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
37
A1340
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
TC2_SENS_CLD (Register Address: 0x08, bits 14:6)
TC2_SENS_HOT (Register Address: 0x08, bits 23:15)
Function
2nd Order Sensitivity Temperature Coefficient.
Specifies a compensation factor for drift in device Sensitivity resulting from changes in ambient temperature
during operation. Applies a 2nd order, quadratic compensation algorithm. Two different parameters are set, one for
increasing values relative to TA = 25°C, and the other for decreasing values, as follows:
• TC2_SENS_HOT: ΔT (from 25°C) > 0
• TC2_SENS_CLD: ΔT (from 25°C) < 0
Syntax
Quantity of bits: 9 (each parameter)
Related Commands
SENS_MULT, TC1_SENS_HOT, TC1_SENS_CLD
Values
1 0000 0000: –1.53 m% / °C
0 1111 1111: +1.53 m% / °C
Increments (step size) of ±0.00596 m% / °C
Options
Set all bits to 0 if TC2_SENS_HOT and TC2_SENS_CLD are not used.
Examples
Refer to Temperature Compensation section.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
38
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
A1340
DEFINITIONS OF TERMS
Power-On Time, tPO
The time required for device output to settle within ±10% of its
steady state value, after the power supply has reached its minimum specified operating voltage, VCC(min). When the supply is
ramped to its operating voltage, the device requires a finite time
to power internal circuits before supplying a valid output value.
See Figure 13.
Response Time, tRESP
The time interval between a) when the applied magnetic field
reaches 90% of its final intensity, and b) when the device output
reaches 90% of its change corresponding to the magnetic field
change. See Figure 14. Response time is affected by the programmed bandwidth, f3dB , for the DSP stage.
Quiescent Voltage Output (QVO), VOUT(Q)
Magnetic Offset Drift Through Temperature
Range
Due to internal component tolerances and thermal considerations, the magnetic offset may drift from its expected value,
BOFFEXPECTED , when changes occur in the operating ambient
temperature, TA. For purposes of specification, the Offset Drift
Through Temperature Range, ∆BOFF(TC) , is defined as:
∆BOFF(TC) =
The proportion of the output voltage to the magnitude of the
applied magnetic field. This proportionality is specified as the
Sensitivity, Sens (mV/G), and is effectively the gain of the
device.
V
VOUT(Q)TA – VOUT(Q)25°C
∆VOUT =
TA – 25°C
.
(2)
where VOUT is measured quiescent output value at temperature TA.
%
t1
Applied Magnetic Field
100
VCC(min.)
90
B
VCC
.
× 100 (%) (1)
The Offset Temperature Coefficient can be seen as a representation of the offset drift over temperature in units mV/°C:
Supply Voltage
t1
BOFFEXPECTED(TA)
where BOFF(TA) is the actual magnetic offset at the current ambient temperature, and BOFFEXPECTED(TA) is the magnetic offset
calculated based on factory programmed parameters.
The output value in the quiescent state (when no magnetic field is
applied, BIN = 0 G).
Sensitivity, Sens
BOFF(TA) – BOFFEXPECTED(TA)
t1= time at which power supply reaches
minimum specified operating voltage
tPO
VOUT
A1340 Output
VOUT
%
100
90
t1= time at which applied magnetic field
reaches 90% of operating intensity
%
100
90
0
time
Figure 13: Definition of Power-On Time
A1340 Output
t2
t2
t2= time at which output voltage initially
generates a valid output
tRESP
VOUT(Q) =
2.5 V (typ)
t2= time at which output voltage initially
reaches 90% of its corresponding value
time
Figure 14: Definition of Response Time
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
39
A1340
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
Sensitivity Drift Through Temperature Range
Due to internal component tolerances and thermal considerations,
the Sensitivity may drift from its expected value, SensEXPECTED ,
when changes occur in the operating ambient temperature, TA.
For purposes of specification, the Sensitivity Drift Through Temperature Range, ∆SensTC , is defined as:
∆SensTC =
SensTA – SensEXPECTED(TA)
SensEXPECTED(TA)
× 100 (%) . (3)
where SensTA is the actual Sens at the current ambient temperature, and SensEXPECTED(TA) is the Sens calculated based on
factory programmed parameters.
The Sensitivity Temperature Coefficient can be seen as a representation of the Sensitivity drift in %/°C when when a temperature divider, ∆T = TA – 25°C, is inserted into equation 3.
Sensitivity Drift Due to Package Hysteresis,
∆SensPKG
Package stress and relaxation can cause the device sensitivity at
TA = 25°C to change during and after temperature cycling. For
purposes of specification, the Sensitivity Drift Due to Package
Hysteresis, is defined as:
Sens(25°C)2 – Sens(25°C)1
∆SensPKG =
Sens(25°C)1
× 100 (%)
(4)
where Sens(25°C)1 is the programmed value of Sensitivity at TA =
25°C, and Sens(25°C)2 is the value of Sensitivity at TA = 25°C,
after temperature cycling.
Linearity Sensitivity Error
The A1340 is designed to provide a linear output in response to
a ramping applied magnetic field. Consider two magnetic field
strengths, B1 and B2. Ideally, the sensitivity of a device is the
same for both field strengths, for a given supply voltage and
temperature. Linearity error is present when there is a difference
between the sensitivities measured at B1 and B2.
Linearity Error is calculated separately for the positive
(LinERRPOS) and negative (LinERRNEG) applied magnetic fields.
Linearity error is measured and defined as:
SensBx 

SensBx/2 
× 100 (%)
Sens–Bx


LinERRNEG = 1–
Sens–Bx/2

× 100 (%)

LinERRPOS = 1–

(5)
where:
SensBx =
|VOUT(Bx) – VOUT(Q)|
Bx
(6)
and BX and –BX are positive and negative magnetic fields
Final Linearity Sensitivity Error (LinERR) is the maximum value
of the absolute positive and absolute negative linearization errors.
Note that unipolar devices only have positive linearity error
(LinERRPOS).
Ratiometric
The A1340 features ratiometric output. This means that the quiescent voltage output, VOUT(Q) , magnetic sensitivity, Sens, and
clamp voltage, VOUTCLP , are proportional to the supply voltage,
VCC .
The ratiometric change in the quiescent output voltage,
RatVOUT(Q) (%), is defined as:
RatVOUT(Q) =
VOUT(Q)VCC / VOUT(Q)5V
VCC / 5 V
× 100 (%)
(7)
the ratiometric change in sensitivity is defined as:
RatSENS =
SensVCC / Sens5V
VCC / 5 V
× 100 (%)
(8)
and the ratiometric change in clamp voltage is defined as:
RatVCLP =
VCLP(VCC) / VCLP(5V)
VCC / 5 V
× 100 (%)
(9)
Note that clamping effect is applicable only when clamping is
enabled by programming of the device.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
40
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
A1340
CUSTOMER PACKAGE DRAWING
For Reference Only - Not for Tooling Use
(Reference DWG-9202)
Dimensions in millimeters - NOT TO SCALE
Dimensions exclusive of mold flash, gate burs, and dambar protrusions
Exact case and lead configuration at supplier discretion within limits shown
B
10°
5.21
+0.08
–0.05
1.00
+0.08
–0.05
E
2.60 F
Mold Ejector
Pin Indent
1.69 F
+0.08
3.43
–0.05
F
0.89 MAX
1
2
3
Branded
Face
4
A
0.54 REF
NNNN
YYWW
0.41
+0.08
0.20
–0.05
+0.08
–0.05
D
12.14 ±0.05
1.27 NOM
N = Device part number
Y = Last two digits of year of manufacture
W = Week of manufacture
0.54 REF
0.89 MAX
1.50
+0.08
–0.05
D
+0.08
5.21
–0.05
Standard Branding Reference View
A
Dambar removal protrusion (16X)
B
Gate and tie burr area
C
Branding scale and appearance at supplier discretion
D
Thermoplastic Molded Lead Bar for alignment during shipment
E
Active Area Depth, 0.37 mm REF
F
Hall element, not to scale
+0.08
1.00
–0.05
Figure 15: Package KT, 4-Pin SIP
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
41
High Precision Programmable Linear Hall Effect Sensor IC
with EEPROM, Analog Output, and Advanced Output Linearization
A1340
Revision History
Revision
Revision Date
–
September 16, 2014
Description of Revision
1
December 2, 2014
Revised Selection Guide
2
February 12, 2015
Revised Package Drawing
Initial Release
Copyright ©2015, Allegro MicroSystems, LLC
Allegro MicroSystems, LLC reserves the right to make, from time to time, such departures from the detail specifications as may be required to
permit improvements in the performance, reliability, or manufacturability of its products. Before placing an order, the user is cautioned to verify that
the information being relied upon is current.
Allegro’s products are not to be used in any devices or systems, including but not limited to life support devices or systems, in which a failure of
Allegro’s product can reasonably be expected to cause bodily harm.
The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, LLC assumes no responsibility for its
use; nor for any infringement of patents or other rights of third parties which may result from its use.
For the latest version of this document, visit our website:
www.allegromicro.com
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
42