A6861 Datasheet

A6861
Automotive 3-Phase Isolator MOSFET Driver
FEATURES AND BENEFITS
•
•
•
•
•
•
•
3 floating N-channel MOSFET drives
Maintains VGS with 100 kΩ gate-source resistors
Integrated charge pump controller
4.5 V-50 V Supply voltage operating range
Independent TTL input for each phase
150°C ambient (165°C junction) continuous
A2-SILTM Product – device features for safety critical
systems
APPLICATIONS
•
•
•
•
3-phase safety disconnect systems
Electric power steering (EPS)
Electric braking
3-phase Solid State Relay driver
Package: 16-Lead TSSOP with exposed
thermal pad (suffix LP)
Not to scale.
DESCRIPTION
The A6861 is an N-channel power MOSFET driver capable
of controlling MOSFETs connected as a 3-phase solid state
relay in phase-isolation applications. The A6861 is intended
for automotive systems that must meet ASIL requirements. In
safety critical applications motor isolation is a critical safety
requirement which is currently addressed with discrete circuitry
or relays. Allegro A2-SILTM products include specific features
that compliment proper system design, allowing users to achieve
up to ASIL-D system rating.
The A6861 has three independent floating gate drive outputs
to maintain the power MOSFETs in the on state over the full
supply range with high phase-voltage slew rates. An integrated
charge pump regulator provides the above battery supply
voltage necessary to maintain the power MOSFETs in the
on state continuously when the phase voltage is equal to the
battery voltage. The charge pump will maintain sufficient gate
drive (>7.5 V) for battery voltages down to 4.5 V with 100 kΩ
gate-source resistors.
The three gate drives can be independently controlled by a logic
level control input. In typical applications the MOSFETs will
be switched on within 8 µs and will switch off within 1 µs.
An undervoltage monitor checks that the pumped supply voltage
is high enough to ensure that the MOSFETs are maintained in
a safe conducting state.
Continued on the next page…
Typical Application Diagram
6861-DS, Rev. 2
A6861
Automotive 3-Phase Isolator MOSFET Driver
Description (continued)
The A6861 is supplied in a 16-lead TSSOP (LP), with exposed pad
for enhanced thermal dissipation. They are lead (Pb) free, with 100%
matte tin leadframe plating.
Selection Guide
Part Number
Packing
A6861KLPTR-T
13-in. reel, 4000 pieces/reel
Package
16-Lead TSSOPwith exposed thermal
pad, 4.4 X 5 mm case
SPECIFICATIONS
Absolute Maximum Ratings1
Characteristic
Symbol
Rating
Units
VBB
–0.3 to 50
V
Terminal VCP
VCP
VBB – 0.3 to
VBB + 12
V
Terminal CP1
VCP1
VBB – 12 to
VBB + 0.3
V
Terminal CP2
VCP2
VBB – 0.3 to
VCP4 + 0.3
V
Terminal CP3
VCP3
VBB – 12 to
VBB + 0.3
V
Terminal CP4
VCP4
VCP2 – 0.3 to
VCP + 0.3
V
VI
–0.3 to 50
V
Terminal GU, GV, GW
VGX
VSX – 0.3 to
VSX + 12
V
Terminal SU, SV, SW
VSX
– 6 to VBB + 5
V
–40 to 150
ºC
165
ºC
175
ºC
–55 to 150
ºC
Load Voltage Supply
Terminal ENU, ENV, ENW
Operating Ambient Temperature
TA
Maximum ContinuousJunction Temperature
Limited by power dissipation
TJ(max)
Transient Junction Temperature
TJt
Storage Temperature
Tstg
1With
Notes
Over temperature event not exceeding 10s, lifetime
duration not exceeding 10hours, guaranteed by design
characterization.
respect to GND. Ratings apply when no other circuit operating constraints are present.
THERMAL CHARACTERISTICS may require derating at maximum conditions, see application information
Characteristic
Symbol
Package Thermal Resistance
(Junction to Ambient)
RθJA
Package Thermal Resistance
(Junction to Pad)
RθJP
Test Conditions*
Value
Units
4-layer PCB based on JEDEC standard
34
ºC/W
1-layer PCB with copper limited to solder pads
43
ºC/W
2
ºC/W
*Additional thermal data available on the Allegro Web site.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
2
A6861
Automotive 3-Phase Isolator MOSFET Driver
Pin-out Diagram and Terminal List Table
VBB
1
16
VCP
CP4
2
15
GU
CP3
3
14
SU
CP2
4
13
GV
CP1
5
12
SV
ENU
6
11
GW
ENV
7
10
SW
ENW
8
9
GND
Package LP, 16-Pin TSSOP Pin-out Diagram
Terminal List Table
Name
Number
Description
VBB
1
Main Power Supply
CP4
2
Pump Capacitor Connection
CP3
3
Pump Capacitor Connection
CP2
4
Pump Capacitor Connection
CP1
5
Pump Capacitor Connection
ENU
6
U phase Enable Input
ENV
7
V phase Enable Input
ENW
8
W phase Enable Input
GND
9
Ground
SW
10
W Phase MOSFET Source Reference
GW
11
W Phase MOSFET Gate Drive
SV
12
V Phase MOSFET Source Reference
GV
13
V Phase MOSFET Gate Drive
SU
14
U Phase MOSFET Source Reference
GU
15
U Phase MOSFET Gate Drive
VCP
16
Pump Supply
Tab
Exposed Tab - Connect to GND
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
3
A6861
Automotive 3-Phase Isolator MOSFET Driver
Battery
VCP
Optional
Reverse
Protected
Supply
Network
Bridge
VCP
C VCP
VCP
Floating
Gate-Drive
VBB
GU
R GPD
CP4
SU
CCP2
CP3
CP2
Protected
Supply
Motor
Charge Pump
Bridge
VCP
CCP1
Floating
Gate-Drive
CP1
GV
GND
R GPD
SV
Motor
Level Shift
ENU
R PD
Level Shift
ENV
R PD
Floating
Gate-Drive
Level Shift
ENW
Bridge
VCP
R PD
GW
R GPD
SW
Motor
GND
Functional Block Diagram
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
4
A6861
Automotive 3-Phase Isolator MOSFET Driver
ELECTRICAL CHARACTERISTICS at TJ = -40 to +150°C, VBB 6 V to 50 V (unless noted otherwise)
Characteristics
Symbol
Test Conditions
Min.
Typ.
Max.
Units
Supply
Operating. Outputs active.
VBB Functional Operating Range1
VBB Quiescent Current
4.5
–
50
V
Operating. Outputs disabled
4
–
50
V
No unsafe states.
0
–
50
V
IBBQ
Gate drive active, VBB = 12 V,
Sx = GND.
–
10
13.5
mA
IBBS
Gate drive disabled, VBB = 12 V
–
5.5
8
mA
9
10
11
V
8
10
11
V
4.5 V < VBB ≤ 6 V, IVCP > - 800 µA[2]
7.5
9.5
–
V
Between VCP and VBB
100
–
–
kΩ
CLOAD = 10 nF, 20% to 80%
CLOAD = 10 nF, 80% to 20%
–
–
5
0.5
–
–
µs
µs
µs
VBB
VBB > 9V, IVCP > -1
VCP Output voltage w.r.t. VBB
VCP Static Load Resistance
VCP
RCP
mA[2]
6 V < VBB ≤ 9 V, IVCP > -1 mA[2]
Gate Output Drive
Turn-on Time
Turn-off Time
tr
tr
Propagation Delay – Turn On3
tPON
CLOAD = 10 nF, ENx high to Gx 20%
–
–
3
Propagation Delay – Turn Off3
tPOFF
CLOAD = 10 nF, ENx low to Gx 80%
–
–
1.5
µs
Turn-on Pulse Current
IGXP
–
14
–
mA
Turn-on Pulse Time
tGXP
–
12.5
–
µs
On Hold Current
IGXH
–
400
–
μA
Pull-down On Resistance
RDS(on)DN
TJ = 25°C, IGx= 10 mA
–
5
–
Ω
TJ = 150°C, IGx = 10 mA
–
10
–
Ω
8.5
10
12
V
VBB > 9 V
Gx Output high voltage
w.r.t. SX, or VBB if SX>VBB
VGH
Gate Drive Static Load Resistance
Gx Output Voltage Low
Gx Passive Pull-down
RGPD
6 V < VBB ≤ 9 V
8
10
12
V
4.5 V < VBB ≤ 6 V
7.5
9.5
–
V
RGS
Between Gx and Sx
100
–
–
kΩ
VGL
-10 µA < IGx < 10 µA
–
–
VSX +0.3
V
VGx - VSx < 0.3 V
–
950
–
kΩ
V
Logic Inputs & Outputs
Input Low Voltage
VIL
–
–
0.8
Input High Voltage
VIH
2.0
–
–
V
Input Hysteresis
VIhys
150
300
–
mV
Input Pull-down Resistor
RPD
30
50
70
kΩ
tCPON
–
100
–
µs
Diagnostics & Protection
VCP Undervoltage Start-up Blank
Timer
VCP Undervoltage Lockout
VCPON
VCP w.r.t. VBB. VCP rising
6.2
6.7
7.2
V
VCPOFF
VCP w.r.t. VBB. VCP falling
6.0
6.5
7.0
V
Function is correct but parameters are not guaranteed below the general limits (6-50V).
2 For input and output current specifications, negative current is defined as coming out of (sourcing) the specified device terminal.
3 Refer to Figure 1.
1
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
5
A6861
Automotive 3-Phase Isolator MOSFET Driver
FUNCTIONAL DESCRIPTION
The A6861 is an N-channel power MOSFET driver capable of
controlling MOSFETs connected as a 3-phase solid state relay
in phase-isolation applications. It has three independent floating
gate drive outputs to maintain the power MOSFETs in the ON
state over the full supply range when the phase outputs are PWM
switched with high phase-voltage slew rates.
A charge pump regulator provides the above battery supply voltage necessary to maintain the power MOSFETs in the ON state
continuously when the phase voltage is equal to the battery voltage. Voltage regulation is based on the difference between VBB
and VCP.
The charge pump will maintain sufficient gate drive (>7.5 V) for
battery voltages down to 4.5 V. It is also able to provide the current taken by gate-source resistors as low as 100 kΩ should they
be required, between the source and gate of the power MOSFETS.
The voltage generated by the charge pump can also be used to
power circuitry to control the gate-source voltage for a MOSFET
connected to the main supply to provide reverse battery protection.
The three gate drives can be controlled independently by three
logic level enable inputs. In typical applications the MOSFETs
will be switched on within 8 µs and will switch off within 1 µs.
An undervoltage monitor checks that the pumped supply voltage
is high enough to ensure that the MOSFETs are maintained in a
safe conducting state
Input & Output Terminal Functions
VBB: Main power supply. The main power supply should be
connected to VBB through a reverse voltage protection circuit.
GND: Main power supply return. Connect to supply ground.
VCP: Pumped gate drive voltage. Can be used to turn on a
MOSFET connected to the main supply to provide reverse battery
protection. Connect a 1 µF ceramic capacitor between VCP and
VBB.
CP1, CP2: Pump capacitor connections. Connect a 330 nF
ceramic capacitor between CP1 and CP2.
CP3, CP4: Pump capacitor connections. Connect a 330 nF
ceramic capacitor between CP3 and CP4.
ENU, ENV, ENW: Logic level enable inputs to control the gate
drive outputs.
GU, GV, GW: Floating, gate-drive outputs for external n-channel
MOSFETs.
SU, SV, SW: Load phase connections. These terminals are the
reference connections for the floating gate-drive outputs.
ENx
t POFF
t PON
V GSx
80%
80%
20%
20%
tf
tR
Figure 1: Enable Inputs to VGS Timing
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
6
A6861
Automotive 3-Phase Isolator MOSFET Driver
Power Supplies
A single reverse polarity protected power supply voltage is
required. It is recommended that the VBB supply is decoupled
to GND by ceramic capacitors mounted close to the device pins.
Decoupling capacitors are not required for correct operation but
will assist in reducing switching noise conducted to the supply
from the charge pump switching circuits.
The A6861 will operate within specified parameters with VBB
from 6 V to 50 V and will function correctly with a supply down
to 4.5 V. This provides a very rugged solution for use in the harsh
automotive environment and permits use in start-stop systems.
There are no unsafe device states, even at low supply voltage. As
the supply voltage rises from 0 V, the gate drive outputs are maintained in the off state until the gate voltage is sufficiently high to
ensure conduction and the outputs are enabled.
Pump Regulator
The gate drivers are powered by a regulated charge pump, which
provides the voltage above VBB to ensure that the MOSFETs
are fully enhanced with low on-resistance when the source of the
MOSFET is at the same voltage as VBB.
Voltage regulation is based on the difference between the VBB
and VCP pins.
The pumped voltage, VCP, is available at the VCP terminal and is
limited to 12 V maximum with respect to VBB. This removes the
need for external clamp diodes on the power MOSFETs to limit
the gate source voltage.
It also allows the VCP terminal to be used to power circuitry
to control a MOSFET connected to the main supply to provide
reverse battery protection.
To provide the continuous low level current required when gatesource resistors are connected to the external MOSFETs, a pump
storage capacitor, typically 1 µF, has to be connected between the
VCP and VBB terminals. Pump capacitors, typically 330 nF, have
to be connected between the CP1 and CP2 terminals and between
the CP3 and CP4 terminals to provide sufficient charge transfer,
especially at low supply voltage.
Gate Drives
The A6861 is designed to drive external, low on-resistance,
power N-channel MOSFETs when used in a phase isolation
application. The gate drive outputs and the VCP supply will turn
the MOSFETs on in typically 8 µs and will maintain the on-state
during transients on the source of the MOSFETs. The gate drive
outputs will turn the MOSFETs off in typically 1 µs and will hold
them in the off-state during transients on the source. An internal
resistor, RGPD, between the Gx and Sx pins plus an integrated
hold-off circuit, will ensure that the gate-source voltage of the
MOSFET is held close to 0 V even with the power disconnected.
This can remove the need for additional gate-source resistors
on the isolation MOSFETs. In any case, if gate-source resistors
are mandatory for the application then the pump regulator can
provide sufficient current to maintain the MOSFET in the on state
with a gate-source resistor of as low as 100 kΩ.
The floating gate-drive outputs for external N-channel MOSFETs
are provided on pins GU, GV, and GW. Gx=1 (or “high”) means
that the upper half of the driver is turned on and current will be
sourced to the gate of the MOSFET in the phase isolation circuit,
turning it on. Gx=0 (or “low”) means that the lower half of the
driver is turned on and will sink current from the external MOSFET’s gate to the respective Sx terminal, turning it off.
The reference points for the floating drives are the load phase
connections, SU, SV, and SW. The discharge current from the
floating MOSFET gate capacitance flows through these connections.
In some applications it may be necessary to provide a current
recirculation path when the motor load is isolated. This will be
necessary in situations where the motor driver does not reduce
the load current to zero before the isolation MOSFETs are turned
off.
The recirculation path can be provided by connecting a suitably
rated power diode to the “motor” side of the isolation MOSFETs
and GND. See the Functional Block Diagram for more details.
Only three diodes are required since the source to drain diodes in
the isolation and bridge MOSFETs provide a recirculation path to
the Battery connection.
Logic Control Inputs
Three TTL level digital inputs, ENU, ENV, & ENW, provide
independent control for each gate drive. The three enable inputs
directly control their respective gate drive outputs. When an
enable input is high the corresponding gate drive output will be
on.
These inputs have nominal hysteresis of 300 mV to improve
noise performance and can be shorted to VBB without damage.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
7
A6861
Automotive 3-Phase Isolator MOSFET Driver
Supply Monitor
The A6861 includes undervoltage detection on the charge pump
output. If the voltage at the charge pump output, VCP , drops
below the falling undervoltage threshold, VCPOFF , then the gate
drive outputs will be held in the off state. They will remain in
that state until VCP rises above the rising undervoltage threshold
VCPON.
Input and Output Structures
VCP
VESD
ENU
ENV
ENW
GU
GV
GW
200 k
R GPD
VESD
50 k
11 V
4V
SU
SV
SW
6V
Figure 3: Drive Outputs
Figure 2: ENU, ENV, ENW Inputs
VBB
12 V
VCP
VESD
12 V
12 V
16 V
16 V
20 V
CP1
CP3
CP2
CP4
Figure 4: Supplies
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
8
A6861
Automotive 3-Phase Isolator MOSFET Driver
Battery Voltage Reversal Protection
The charge pump output voltage may be used to drive a reverseconnected battery protection circuit as illustrated in Figure 5.
Battery
VCP
R1
When the battery voltage is reversed the voltage between VBB
and VCP is zero, the gate source voltage on Q1 is zero and its
source to drain diode becomes reverse biased. In this condition
Q1 blocks current flow to VBB and the voltage between VBB
and GND remains at Zero.
Transistor Q2 is a normally connected p channel, small signal MOSFET used to control the gate of Q1 in the normal and
reversed battery voltage condition. Both Q1 and Q2 must be correctly rated for the full peak reversed battery voltage.
Q2
Q1
Transistor Q1 is an n-channel power MOSFET selected to create
a low voltage drop at the full current rated for the motor drive
system. It is connected with source and drain pins reversed from
the normal biased condition. During power up the initial system
current is supplied to VBB through the forward biased parasitic
source to drain diode until VCP has exceeded the threshold voltage of Q1 and turned it on.
Protected
VBB
Resistor R1 is used to control the gate to source voltage of Q1
and is powered from the VCP supply. To reduce the current drain
from VCP the value of R1 should be a minimum defined for RCP,
100 k.
Figure 5: Indicative Reverse Voltage Protection Scheme
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
9
A6861
Automotive 3-Phase Isolator MOSFET Driver
PACKAGE OUTLINE DRAWING
For Reference Only – Not for Tooling Use
(Reference MO-153 ABT)
Dimensions in millimeters. NOT TO SCALE
Dimensions exclusive of mold flash, gate burrs, and dambar protrusions
Exact case and lead configuration at supplier discretion within limits shown
0.65
0.45
8º
0º
5.00 ±0.10
16
16
0.20
0.09
1.70
B
3 (NOM)
4.40 ±0.10
3.00 (NOM)
6.40 ±0.20
A
6.10
0.60 ±0.15
1.00 (REF)
1
2
3 (NOM)
1
0.29 (BSC)
2
Branded Face
3.00
SEATING PLANE
C
16X
0.10
C
GAUGE PLANE
C
SEATING
PLANE
0.30
0.19
1.20 (MAX)
0.65 (BSC)
NNNNNNN
YYWW
LLLL
0.15
0.00
A
Terminal #1 mark area
B
Exposed thermal pad (bottom surface); dimensions may vary with device
C
Reference land pattern layout (reference IPC7351 SOP65P640X110-17M);
All pads a minimum of 0.20 mm from all adjacent pads; adjust as necessary
to meet application process requirements and PCB layout tolerances; when
mounting on a multilayer PCB, thermal vias at the exposed thermal pad land
can improve thermal dissipation (reference EIA/JEDEC Standard JESD51-5)
D
PCB Layout Reference View
1
D Standard Branding Reference View
N = Device part number
= Supplier emblem
Y = Last two digits of year of manufacture
W = Week of manufacture
L = Characters 5-8 of lot number
Branding scale and appearance at supplier discretion
Figure 6: LP Package, 16-Lead TSSOP with Exposed Pad
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
10
A6861
Automotive 3-Phase Isolator MOSFET Driver
Revision
Date
–
February 26, 2014
1
August 25, 2014
2
May 28, 2015
Change
Initial Release
Various text edits throughout; reformatted document
Corrected typo on Package Outline Drawing
Copyright ©2014-15, Allegro MicroSystems, LLC
Allegro MicroSystems, LLC (“Allegro”) products may, in certain cases, be promoted to assist with applications related to safety. Allegro’s objective is to provide an opportunity for customers to design and develop their own end-products that meet functional safety standards and requirements.
However, Allegro’s products are not to be used in any devices or systems in which a failure of Allegro’s product can reasonably be expected to cause
bodily harm. Customer agrees that it has sole responsibility for compliance with all applicable laws, regulations, and safety-related requirements
regarding its products. Customer shall indemnify Allegro and its representatives against any damages arising out of the use of any Allegro products in
safety-critical applications.
Allegro assumes no responsibility for the intended use of its products, nor for any infringement of patents or other rights of third parties which may
result from their use.
Allegro 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, customer is cautioned to verify the detailed specifications.
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
11
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