Allegro A1205LLHLT-T Continuous-time bipolar switch Datasheet

A1205
Continuous-Time Bipolar Switch
Features and Benefits
Description
▪ Ideal for applications that require pulsing VCC to
conserve power
▪ Continuous-time operation
▫ Fast power-on time
▫ Low noise
▪ Stable operation over full operating temperature range
▪ Reverse battery protection
▪ Solid-state reliability
▪ Factory-programmed at end-of-line for optimum
performance
▪ Robust EMC performance
▪ High ESD rating
▪ Regulator stability without a bypass capacitor
The Allegro® A1205 Hall-effect bipolar switch is a nextgeneration replacement and extension of the popular Allegro
A3134 bipolar switch. The A1205 has identical specifications
as the A1201 but is recommended for applications that require
pulsing VCC to conserve power. For standard applications,
where VCC is constant, please refer to the A1201 through
A1204 devices.
Overall, the A120x family, produced with BiCMOS technology,
consists of continuous-time devices that feature fast poweron time and low-noise operation. Device programming is
performed after packaging to ensure increased switchpoint
accuracy by eliminating offsets that can be induced by
package stress. Unique Hall element geometries and lowoffset amplifiers help to minimize noise and to reduce the
residual offset voltage normally caused by device overmolding,
temperature excursions, and thermal stress.
Packages:
The A120x Hall-effect bipolar switches include the following on
a single silicon chip: voltage regulator, Hall-voltage generator,
3 pin SOT23W (LH)
3 pin SIP (UA)
Continued on the next page…
Not to scale
Functional Block Diagram
VCC
To all subcircuits
Regulator
VOUT
Amp
Gain
Offset
Trim
Control
GND
A1205-DS, Rev. 1
Continuous-Time Bipolar Switch
A1205
Description (continued)
small-signal amplifier, Schmitt trigger, and NMOS output transistor.
The integrated voltage regulator permits operation from 3.8 to
24 V. The extensive on-board protection circuitry makes possible
a ±30 V absolute maximum voltage rating for superior protection
in automotive and motor commutation applications, without adding
external components.
The small geometries of the BiCMOS process allow these devices
to be provided in ultrasmall packages. The package styles available
provide magnetically optimized solutions for most applications.
Package LH is a SOT23W miniature thin-profile surface-mount
package, while package UA is a three-lead ultramini SIP for throughhole mounting. Each package is lead (Pb) free, with 100% matte
tin plated leadframes.
Selection Guide
Part Number
Packing*
Mounting
Ambient, TA
A1205ELHLT-T
7-in. reel, 3000 pieces/reel
3-pin SOT23W surface mount
A1205EUA-T
Bulk, 500 pieces/bag
3-pin SIP through hole
A1205LLHLT-T
7-in. reel, 3000 pieces/reel
3-pin SOT23W surface mount
A1205LUA-T
Bulk, 500 pieces/bag
3-pin SIP through hole
BRP (Min)
BOP (Max)
–50
50
–40ºC to 85ºC
–40ºC to 150ºC
*Contact Allegro for additional packing options.
Absolute Maximum Ratings
Characteristic
Symbol
Notes
Rating
Units
Supply Voltage
VCC
30
V
Reverse Supply Voltage
VRCC
–30
V
Output Off Voltage
VOUT
30
V
Reverse Output Voltage
VROUT
–0.5
V
IOUTSINK
25
mA
B
Unlimited
G
Range E
–40 to 85
ºC
Range L
Output Current Sink
Magnetic Flux Density
Operating Ambient Temperature
TA
–40 to 150
ºC
Maximum Junction Temperature
TJ(max)
165
ºC
Tstg
–65 to 170
ºC
Storage Temperature
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
Continuous-Time Bipolar Switch
A1205
OPERATING CHARACTERISTICS over full operating voltage and ambient temperature ranges, unless otherwise noted
Characteristic
Symbol
Test Conditions
Min.
Typ.
Max.
Units
Electrical Characteristics
Supply Voltage1
Output Leakage Current
Output On Voltage
Power-On Time2
Output Rise Time3
Output Fall
Time3
Supply Current
Reverse Battery Current
VCC
Operating, TJ < 165°C
3.8
–
24
V
IOUTOFF
VOUT = 24 V, B < BRP
–
–
10
µA
VOUT(SAT)
IOUT = 20 mA, B > BOP
–
215
400
mV
Slew rate (dVCC/dt) < 2.5 V/μs, B > BOP + 5 G or
B < BRP – 5 G
–
–
4
µs
tr
VCC = 12 V, RLOAD = 820 Ω, CS = 12 pF
–
–
2
µs
tf
tPO
VCC = 12 V, RLOAD = 820 Ω, CS = 12 pF
–
–
2
µs
ICCON
B > BOP
–
3.8
7.5
mA
ICCOFF
B < BRP
–
3.5
7.5
mA
VRCC = –30 V
–
–
–10
mA
IRCC
Supply Zener Clamp Voltage
VZ
ICC = 30 mA; TA = 25°C
32
–
40
V
Supply Zener Current
IZ
VZ = 32 V; TA = 25°C
–
–
30
mA
Magnetic
Characteristics4
Operate Point
BOP
South pole adjacent to branded face of device
–40
15
50
G
Release Point
BRP
North pole adjacent to branded face of device
–50
–15
40
G
Hysteresis
BHYS
BOP – BRP
5
30
55
G
Maximum voltage must be adjusted for power dissipation and junction temperature, see Power Derating section.
2 For V
CC slew rates greater than 2.5 V/μs, and TA = 150°C, the Power-On Time can reach its maximum value.
3 C =oscilloscope probe capacitance.
S
4 Magnetic flux density, B, is indicated as a negative value for north-polarity magnetic fields, and as a positive value for south-polarity magnetic fields.
This so-called algebraic convention supports arithmetic comparison of north and south polarity values, where the relative strength of the field is indicated
by the absolute value of B, and the sign indicates the polarity of the field (for example, a –100 G field and a 100 G field have equivalent strength, but
opposite polarity). Reference to the magnetic field polarity is with respect to the beveled face of the device.
1
DEVICE QUALIFICATION PROGRAM
Contact Allegro for information.
EMC (Electromagnetic Compatibility) REQUIREMENTS
Contact Allegro for information.
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
Continuous-Time Bipolar Switch
A1205
THERMAL CHARACTERISTICS may require derating at maximum conditions, see application information
Characteristic
Symbol
RθJA
Package Thermal Resistance
Test Conditions*
Value Units
Package LH, 1-layer PCB with copper limited to solder pads
228
ºC/W
Package LH, 2-layer PCB with 0.463 in.2 of copper area each side
connected by thermal vias
110
ºC/W
Package UA, 1-layer PCB with copper limited to solder pads
165
ºC/W
Maximum Allowable VCC (V)
*Additional thermal information available on Allegro Web site.
Power Derating Curve
TJ(max) = 165ºC; ICC = ICC(max)
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
VCC(max)
Package LH, 1-layer PCB
(R JA = 228 ºC/W)
Package UA, 1-layer PCB
(R JA = 165 ºC/W)
Package LH, 2-layer PCB
(R JA = 110 ºC/W)
VCC(min)
20
40
60
80
100
120
140
160
180
Power Dissipation, PD (m W)
Power Dissipation versus Ambient Temperature
1900
1800
1700
1600
1500
1400
1300
1200
1100
1000
900
800
700
600
500
400
300
200
100
0
2l
(R aye
rP
θJ
C
A =
11 B, P
0 º ac
1-la
C/ ka
W
(R yer PC
) ge L
θJA =
B
H
165 , Pac
ºC/ kage
W)
UA
1-lay
er P
(R
CB,
θJA =
228 Packag
ºC/W
e LH
)
20
40
60
80
100
120
Temperature (°C)
140
160
180
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
Continuous-Time Bipolar Switch
A1205
Characteristic Data
Supply Current (On) versus Ambient Temperature
8.0
8.0
7.0
7.0
VCC (V)
5.0
24
3.8
4.0
3.0
6.0
ICCON (mA)
6.0
ICCON (mA)
Supply Current (On) versus Supply Voltage
–40
25
150
4.0
3.0
2.0
2.0
1.0
1.0
0
TA (°C)
5.0
0
–50
0
50
TA (°C)
100
150
0
15
20
25
Supply Current (Off) versus Supply Voltage
8.0
8.0
7.0
7.0
6.0
VCC (V)
5.0
24
3.8
4.0
3.0
ICCOFF (mA)
ICCOFF (mA)
10
VCC (V)
Supply Current (Off) versus Ambient Temperature
6.0
TA (°C)
5.0
–40
25
150
4.0
3.0
2.0
2.0
1.0
1.0
0
0
–50
0
50
TA (°C)
100
0
150
10
15
20
25
Output Voltage (On) versus Supply Voltage
ILOAD = 20 mA
350
5
VCC (V)
Output Voltage (On) versus Ambient Temperature
ILOAD = 20 mA
350
300
300
250
VCC (V)
200
24
3.8
150
100
250
TA (°C)
VOUT(SAT) (mV)
VOUT(SAT) (mV)
5
200
–40
25
150
150
100
50
50
0
0
–50
0
50
TA (°C)
100
150
0
5
10
15
20
25
VCC (V)
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
Continuous-Time Bipolar Switch
A1205
Operate Point versus Ambient Temperature
Operate Point versus Supply Voltage
50
50
40
40
30
30
20
VCC (V)
10
24
0
3.8
BOP (G)
BOP (G)
20
TA (°C)
10
–40
25
150
0
-10
-10
-20
-20
-30
-30
-40
-40
-50
0
50
TA (°C)
100
150
0
15
20
25
Release Point versus Supply Voltage
40
40
30
30
20
20
10
10
VCC (V)
0
24
3.8
-10
-20
BRP (G)
BRP (G)
10
VCC (V)
Release Point versus Ambient Temperature
TA (°C)
0
–40
25
150
-10
-20
-30
-30
-40
-40
-50
-50
0
50
100
-50
150
0
TA (°C)
5
10
15
20
25
VCC (V)
Hysteresis versus Ambient Temperature
Hysteresis versus Supply Voltage
55
55
50
50
45
45
VCC (V)
35
24
3.8
30
25
40
TA (°C)
35
BHYS (G)
40
BHYS (G)
5
–40
25
150
30
25
20
20
15
15
10
10
5
-50
0
50
TA (°C)
100
150
5
0
5
10
VCC (V)
15
20
25
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
Continuous-Time Bipolar Switch
A1205
Functional Description
Bipolar Device Switching
The devices of the A120X family provide highly sensitive
switching for applications using magnetic fields of alternating
polarities, such as ring magnets. There are three switching modes
for bipolar devices, referred to as latch, unipolar switch, and
negative switch. Mode is determined by the switchpoint characteristics of the individual device. The characteristic hysteresis,
BHYS , of the device, is the difference in the relative magnetic
strength and polarity of the switchpoints of the device. (Note
that, in the following descriptions, a negative magnetic value
indicates a north polarity field, and a positive magnetic value
indicates a south polarity field. For a given value of magnetic
strength, BX , the values –BX and BX indicate two fields of equal
strength, but opposite polarity. B = 0 indicates the absence of a
magnetic field.)
In contrast to latching, when a device exhibits unipolar switching, it only responds to a south magnetic field. The field must
be of sufficient strength, > BOP , for the device to operate. When
the field is reduced beyond the BRP level, the device switches
back to the high state, as shown in panel B of figure 1. Devices
exhibiting negative switch behavior operate in a similar but
opposite manner. A north polarity field of sufficient strength,
> BRP , (more north than BRP) is required for operation, although
the result is that VOUT switches high, as shown in panel C. When
VS
VCC
Bipolar devices typically behave as latches. In this mode,
magnetic fields of opposite polarity and equivalent strengths
are needed to switch the output. When the magnetic fields are
removed (B → 0) the device remains in the same state until a
magnetic field of the opposite polarity and of sufficient strength
causes it to switch. The hysteresis of latch mode behavior is
shown in panel A of figure 1.
(A)
A120x
GND
(D)
(C)
V+
V+
VOUT
Switch to High
Switch to High
VOUT
BHYS
B+
B–
BRP
BRP
B– 0
VOUT(SAT)
0
BOP
BHYS
B+
VOUT(SAT)
0
BOP
0
BOP
BRP
VOUT(SAT)
VCC
Switch to Low
VOUT
VCC
Switch to Low
Switch to Low
Switch to High
VCC
B–
Sensor Output
VOUT
(B)
V+
0
RL
0
B+
BHYS
Figure 1. Bipolar Device Output Switching Modes. These behaviors can be exhibited when using a circuit such as that shown in panel D. Panel A
displays the hysteresis when a device exhibits latch mode (note that the BHYS band incorporates B= 0), panel B shows unipolar switch behavior (the
BHYS band is more positive than B = 0), and panel C shows negative switch behavior (the BHYS band is more negative than B = 0). Bipolar devices,
such as the 120x family, can operate in any of the three modes.
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
A1205
Continuous-Time Bipolar Switch
the field is reduced beyond the BOP level, the device switches
back to the low state.
CONTINUOUS-TIME BENEFITS
Continuous-time devices, such as the A120x family, offer the
fastest available power-on settling time and frequency response.
Due to offsets generated during the IC packaging process, continuous-time devices typically require programming after packaging
to tighten magnetic parameter distributions. In contrast, chopper-stabilized switches employ an offset cancellation technique
on the chip that eliminates these offsets without the need for
after-packaging programming. The tradeoff is a longer settling
time and reduced frequency response as a result of the chopperstabilization offset cancellation algorithm.
The typical output behavior of the A120x devices is latching.
However, the A120x family is designed to attain a small hysteresis, and thereby provide more sensitive switching. Although
this means that true latching behavior cannot be guaranteed in all
cases, proper switching can be ensured by use of both south and
north magnetic fields, as in a ring magnet. The hysteresis of the
A120x family allows clean switching of the output, even in the
presence of external mechanical vibration and electrical noise.
The choice between continuous-time and chopper-stabilized
designs is solely determined by the application. Battery management is an example where continuous-time is often required. In
these applications, VCC is chopped with a very small duty cycle
in order to conserve power (refer to figure 2). The duty cycle
is controlled by the power-on time, tPO, of the device. Because
Bipolar devices adopt an indeterminate output state when powered-on in the absence of a magnetic field or in a field that lies
within the hysteresis band of the device.
For more information on Bipolar switches, refer to Application
Note 27705, Understanding Bipolar Hall Effect Sensors.
1
2
3
4
5
VCC
t
VOUT
t
tPO(max)
Output Sampled
Figure 2. Continuous-Time Application, B < BRP.. This figure illustrates the use of a quick cycle for chopping VCC in order to conserve battery power.
Position 1, power is applied to the device. Position 2, the output assumes the correct state at a time prior to the maximum Power-On Time, tPO(max).
The case shown is where the correct output state is HIGH . Position 3, tPO(max) has elapsed. The device output is valid. Position 4, after the output is
valid, a control unit reads the output. Position 5, power is removed from the device.
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
A1205
Continuous-Time Bipolar Switch
continuous-time devices have the shorter power-on time, they are
the clear choice for such applications.
ADDITIONAL APPLICATIONS INFORMATION
For more information on the chopper stabilization technique,
refer to Technical Paper STP 97-10, Monolithic Magnetic Hall
Sensor Using Dynamic Quadrature Offset Cancellation and
Technical Paper STP 99-1, Chopper-Stabilized Amplifiers with a
Track-and-Hold Signal Demodulator.
Extensive applications information for Hall-effect sensors is
available in:
• Hall-Effect IC Applications Guide, Application Note 27701
• Hall-Effect Devices: Gluing, Potting, Encapsulating, Lead
Welding and Lead Forming, Application Note 27703.1
• Soldering Methods for Allegro’s Products – SMT and ThroughHole, Application Note 26009
All are provided in Allegro Electronic Data Book, AMS-702, and
the Allegro Web site, www.allegromicro.com.
Pin-out Diagrams
Package UA
GND
Package LH
Name
VCC
VOUT
GND
Description
Connects power supply to chip
Output from circuit
Ground
2
3
VOUT
VOUT
Terminal List
1
GND
2
VCC
1
VCC
3
Number
Package LH Package UA
1
1
2
3
3
2
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
Continuous-Time Bipolar Switch
A1205
Power Derating
Power Derating
The device must be operated below the maximum junction
temperature of the device, TJ(max). Under certain combinations of
peak conditions, reliable operation may require derating supplied power or improving the heat dissipation properties of the
application. This section presents a procedure for correlating
factors affecting operating TJ. (Thermal data is also available on
the Allegro MicroSystems Web site.)
The Package Thermal Resistance, RθJA, is a figure of merit summarizing the ability of the application and the device to dissipate
heat from the junction (die), through all paths to the ambient air.
Its primary component is the Effective Thermal Conductivity,
K, of the printed circuit board, including adjacent devices and
traces. Radiation from the die through the device case, RθJC, is
relatively small component of RθJA. Ambient air temperature,
TA, and air motion are significant external factors, damped by
overmolding.
The effect of varying power levels (Power Dissipation, PD), can
be estimated. The following formulas represent the fundamental
relationships used to estimate TJ, at PD.
PD = VIN × IIN
(1)
ΔT = PD × RθJA (2)
TJ = TA + ΔT
Example: Reliability for VCC at TA = 150°C, package UA, using
minimum-K PCB.
Observe the worst-case ratings for the device, specifically:
RθJA = 165°C/W, TJ(max) = 165°C, VCC(max) = 24 V, and
ICC(max) = 7.5 mA.
Calculate the maximum allowable power level, PD(max). First,
invert equation 3:
ΔTmax = TJ(max) – TA = 165 °C – 150 °C = 15 °C
This provides the allowable increase to TJ resulting from internal
power dissipation. Then, invert equation 2:
PD(max) = ΔTmax ÷ RθJA = 15°C ÷ 165 °C/W = 91 mW
Finally, invert equation 1 with respect to voltage:
VCC(est) = PD(max) ÷ ICC(max) = 91 mW ÷ 7.5 mA = 12.1 V
The result indicates that, at TA, the application and device can
dissipate adequate amounts of heat at voltages ≤VCC(est).
Compare VCC(est) to VCC(max). If VCC(est) ≤ VCC(max), then reliable operation between VCC(est) and VCC(max) requires enhanced
RθJA. If VCC(est) ≥ VCC(max), then operation between VCC(est) and
VCC(max) is reliable under these conditions.
(3)
For example, given common conditions such as: TA= 25°C,
VCC = 12 V, ICC = 4 mA, and RθJA = 140 °C/W, then:
PD = VCC × ICC = 12 V × 4 mA = 48 mW
ΔT = PD × RθJA = 48 mW × 140 °C/W = 7°C
TJ = TA + ΔT = 25°C + 7°C = 32°C
A worst-case estimate, PD(max), represents the maximum allowable power level (VCC(max), ICC(max)), without exceeding TJ(max),
at a selected RθJA and TA.
10
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
Continuous-Time Bipolar Switch
A1205
Package LH, 3-Pin (SOT-23W)
3.00 .118
2.70 .106
0.15 [.006] M C A B
3.04 .120
2.80 .110
3
A
A
1.49 .059
NOM
B
B
8º
0º
0.20 .008
0.08 .003
2.10 .083
1.85 .073
Preliminary dimensions, for reference only
Dimensions in millimeters
U.S. Customary dimensions (in.) in brackets, for reference only
(reference JEDEC TO-236 AB, except case width and terminal tip-to-tip)
Dimensions exclusive of mold flash, gate burrs, and dambar protrusions
Exact case and lead configuration at supplier discretion within limits shown
A Hall element (not to scale)
B Active Area Depth 0.28 [.011]
A
0.96 .038
0.60 .024
0.25 .010
A NOM
1
2
0.25 .010
3X
SEATING
PLANE
0.10 [.004] C
3X 0.50 .020
0.30 .012
C
SEATING PLANE
GAUGE PLANE
1.17 .046
0.75 .030
0.20 [.008] M C A B
0.15 .006
0.00 .000
0.95 .037
1.90 .075
11
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
Continuous-Time Bipolar Switch
A1205
Package UA, 3-Pin SIP
.164 4.17
.159 4.04
C
D
.122 3.10
.117 2.97
.091 2.31
NOM
.062 1.57
.058 1.47
D
.057 1.45
NOM D
B
.085 2.16
MAX
.031 0.79
REF
Dimensions in inches
Metric dimensions (mm) in brackets, for reference only
A Dambar removal protrusion (6X)
A
B Ejector mark on opposite side
C Active Area Depth .0195 [0.50] NOM
D Hall element (not to scale)
.017 0.44
.014 0.35
.640 16.26
.600 15.24
1
2
3
.019 0.48
.014 0.36
.050 1.27
NOM
The products described herein are manufactured under one or more of the following U.S. patents: 5,045,920; 5,264,783; 5,442,283;
5,389,889; 5,581,179; 5,517,112; 5,619,137; 5,621,319; 5,650,719; 5,686,894; 5,694,038; 5,729,130; 5,917,320; and other patents pending.
Allegro MicroSystems, Inc. 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.
The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, Inc. assumes no responsibility for its use; nor for any infringement of patents or other rights of third parties which may result from its use.
Copyright ©2006, Allegro MicroSystems, Inc.
For the latest version of this document, go to our website at:
www.allegromicro.com
12
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
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