AK8778B [AKM]
HALL EFFECT IC FOR PULSE ENCODERS; 霍尔效应IC的脉冲编码器
| 型号： | AK8778B |
| 厂家： | 
ASAHI KASEI MICROSYSTEMS |
| 描述： | HALL EFFECT IC FOR PULSE ENCODERS |
| 文件： | 总12页 (文件大小：548K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
[AK8778B]
AK8778B
Hall Effect IC for Pulse Encoders
Overview
The AK8778B is a Hall effect latch which detects both “vertical magnetic field” and “horizontal magnetic field”
(perpendicular and parallel to the marking side of the package) at the same time. The pulse output F and direction
output D are switched according to the vertical and horizontal magnetic fields applied to the device. The direction
is calculated internally and output D is switched at a rising or falling edge of output F. The AK8778B is for use in
the incremental pulse encoders or rotational detection systems.
Features
4.0 to 24V supply voltage operation
Sensitivity (Vertical, Horizontal) : ±1.7mT(Typ.)
Two outputs : F (Pulse), D (Direction)
Small package: SOP-6pin
Halogen free
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Block Diagram
VDD
VSS
VREG
F
D
HALL SENSORS
Figure 1. Block diagram
Circuit Configuration
Table 1. Circuit configuration
Block
Function
REGULATOR
HALL SENSORS
CHOPPER_SW
CHOP_AMP
COMP
Generate internal operating voltage.
Two Hall elements fabricated by CMOS process.
Perform chopping in order to cancel the offset of Hall sensor.
Amplifies two Hall sensor output voltage with summation and subtraction circuit.
Hysteresis comparator.
BIAS
Generates bias current to internal circuits.
Generates bias current for Hall sensors.
Generates operating clock.
HE_DRIVE
OSC
Generates timing signal for internal circuits.
Logical circuits and open drain driver.
TIMING LOGIC
LATCH & LOGIC
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Pin/Function
Table 2. Description of pin name and function
Pin No.
Pin name
VDD
TAB
F
I/O
Function
Power supply pin
(TAB pin)
Note
1
2
3
4
5
6
O
O
Output F (Pulse) pin
Output D (Direction) pin
(TAB pin)
Open drain
Open drain
D
TAB
VSS
Ground pin
Note) TAB pins should be connected to VSS.
Absolute Maximum Ratings
Table 3. Absolute maximum ratings
Parameter
Supply voltage
Output voltage
Output current
Symbol
VDD
VOUT
ISINK
Min.
0.3
0.3
Max.
+32
+32
20
Unit
V
V
mA
C
Note
VSS=0V
F,D pin VSS=0V
F,D pin
+150
Storage temperature
TSTG
55
Note) Stress beyond these listed values may cause permanent damage to the device.
Recommended Operating Conditions
Table 4. Recommended operating conditions
Parameter
Supply voltage
Output current
Symbol
VDD
ISINK
Ta
Min.
4.0
Typ.
12.0
Max.
24.0
15
Unit
V
mA
Operating temperature
+125
40
C
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Electrical Characteristics
Table 5. Electrical characteristics at VDD=4.0 to 24.0V, Ta= 40 to +125C
Parameter
Symbol
IDD
VSAT
ILEAK
TP
Min.
1.4
Typ.
3.0
Max.
5.6
0.4
10
30.5
Unit
mA
V
mA
ms
Note
Current consumption
Output saturation voltage
Output leak current
Output refresh period
F, D pin, ISINK= 15mA
F, D=VDD
16.7
12.0
Magnetic Characteristics
Table 6. Magnetic characteristics at VDD=4.0 to 24.0V, Ta= 40 to +125C
Parameter
Operating point of
vertical magnetic field
Releasing point of
vertical magnetic field
Operating point of
horizontal magnetic field
Operating point of
horizontal magnetic field
Hysteresis
Symbol
Min.
Typ.
Max.
Unit
Note
BopV
0.1
1.7
4.0
mT
(*1)
BrpV
BopH
mT
mT
(*1)
(*2)
4.0
1.7
0.1
0.1
1.7
4.0
BrpH
mT
mT
(*2)
4.0
1.7
0.1
BhV, BhH
1.5
3.4
6.8
(*1), (*2)
(*1) Horizontal magnetic flux density is zero.
(*2) Vertical magnetic flux density is zero.
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Operational Characteristics
The internal signal Aswitches „Low‟state when the magnetic field perpendicular to the marking side of the package
exceeds BopV. When the magnetic field is reduced below BrpV, the internal signal A goes „High‟ state. Otherwise;
that is, in case of the magnetic field strength is greater than BrpV and smaller than BopV; the internal signal A keeps
its status.
S
Internal signal A
BhV
Top(Marking)
BopV
BrpV
Bottom
0
N
N
S
Figure 2. Switching behavior of the internal signal A when vertical magnetic field is applied
The internal signal B switches „Low‟ state when the magnetic field parallel to the marking side of the package
exceeds BopH. When the magnetic field is reduced below BrpH, the internal signal B goes „High‟ state. Otherwise;
that is, in case of the magnetic field strength is greater than BrpH and smaller than BopH; the internal signal B keeps
its status.
Internal signal B
BhH
Line Marking
Top(Marking)
VSS pin
S
BopH
BrpH
N
0
N
S
D pin
Bottom
Figure 3. Switching behavior of the internal signal B when horizontal magnetic field is applied
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Behaviors of internal signal A,B and output signal F, D when a rotating magnetic field is applied on AK8778B
F signal (pulse) is correspond to the result of EX-OR operation of internal signal A and B. And signal D (direction)
is calculated by the state of internal signal A and B.
Direction changed
Direction changed
BopV
BrpV
0
0
Vertical M.F.D.
t
t
BopH
BrpH
Horizontal M.F.D.
Supply voltage VDD
0
t
t
Internal signal A
(Vertical)
Internal signal B
(Horizontal)
t
t
t
F (Pulse)
0
0
D (Direction)
Undefined (High or Low)
Signal F, D is determined.
Figure 4. Behaviors of internal signal A,B and signal F, D when a
rotating magnetic field is applied on AK8778B
*M.F.D. is Magnetic Flux Density.
Note) Signal D is determined after one signal F pulse is sent out. The indeterminate output state appears only in the
powering up of this device.
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Functional Timing
TP: 16.7μs(Typ.)
Sampling
Cycle
t
t
Vertical M.F.D.
BopV
0
BrpV
Horizontal M.F.D.
BopH
0
t
BrpH
Internal signal A
(Vertical)
t
t
t
Internal signal B
(Horizontal)
F (Pulse)
0
Figure 5. Timing diagram
*M.F.D. is Magnetic Flux Density.
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Direction
changed
Direction
changed
Sampling
Cycle
t
t
Vertical M.F.D. Horizontal M.F.D.
M.F.D.
BopV,BopH
0
BrpV,BrpH
6μs(Typ.)
6μs(Typ.)
6μs(Typ.)
6μs(Typ.)
6μs(Typ.)
50%VDD
F (Pulse)
0
t
6μs(Typ.)
D (Direction)
0
50%VDD
t
Figure 6. Timing diagram (in detail)
*M.F.D. is Magnetic Flux Density.
Note ) VDD=12.0V ,RL=10k, CL=20pF
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Typical Characteristic Data (for reference)
Figure 7. Temperature dependence of sensitivity
Figure 8. Temperature dependence of current consumption
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Package
6
5
4
1
2
3
1:VDD
2:TAB
3:F
4:D
5:TAB
6:VSS
Unit in mm
Figure 9. Package dimensions
Note 1) The center of the sensitive area is located within the 0.3mm circle.
Note 2) Coplanarity: The differences between standoff of terminals are max. 0.1mm.
Note 3) The sensor part is located 0.71mm(Typ.) from marking surface.
Material of terminals： Cu alloy
Material of plating for terminals： Sn 100％
Thickness of plating for terminals：10μm (Typ.)
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Marking
Line Marking
6
5
4
Marking is performed by laser
Product name ：6 (AK8778B)
Date code
：YWWL
6YWWL
Y：Manufactured year
WW：Manufactured week
L：Lot
1
2
3
Figure 10. Marking
Recommended External Circuit
VDD
Output (F)
GND
VDD
6
1
5
4
3
VDD
Top View
2
Output (D)
Figure 11. Recommended external circuit
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IMPORTANT NOTICE
These products and their specifications are subject to change without notice.
When you consider any use or application of these products, please make inquiries the sales office of Asahi Kasei
Microdevices Corporation (AKM) or authorized distributors as to current status of the products.
Descriptions of external circuits, application circuits, software and other related information contained in this
document are provided only to illustrate the operation and application examples of the semiconductor products. You
are fully responsible for the incorporation of these external circuits, application circuits, software and other related
information in the design of your equipments. AKM assumes no responsibility for any losses incurred by you or third
parties arising from the use of these information herein. AKM assumes no liability for infringement of any patent,
intellectual property, or other rights in the application or use of such information contained herein.
Any export of these products, or devices or systems containing them, may require an export license or other official
approval under the law and regulations of the country of export pertaining to customs and tariffs, currency exchange,
or strategic materials.
AKM products are neither intended nor authorized for use as critical componentsNote1) in any safety, life support, or
other hazard related device or systemNote2), and AKM assumes no responsibility for such use, except for the use
approved with the express written consent by Representative Director of AKM. As used here:
Note1) A critical component is one whose failure to function or perform may reasonably be expected to result,
whether directly or indirectly, in the loss of the safety or effectiveness of the device or system containing it, and
which must therefore meet very high standards of performance and reliability.
Note2) A hazard related device or system is one designed or intended for life support or maintenance of safety or
for applications in medicine, aerospace, nuclear energy, or other fields, in which its failure to function or perform
may reasonably be expected to result in loss of life or in significant injury or damage to person or property.
It is the responsibility of the buyer or distributor of AKM products, who distributes, disposes of, or otherwise places
the product with a third party, to notify such third party in advance of the above content and conditions, and the buyer
or distributor agrees to assume any and all responsibility and liability for and hold AKM harmless from any and all
claims arising from the use of said product in the absence of such notification.
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