View detail for ATA6823 H-bridge Gate Driver with LIN Transceiver, Watchdog, and 5V Regulator

APPLICATION NOTE
H-bridge Gate Driver with LIN Transceiver, Watchdog, and
5V Regulator
ATA6823
Introduction
The Atmel® ATA6823 is designed specifically for automotive applications that require highpower motors. It provides four high-current gate driver outputs capable of driving a wide
range of n-channel power MOSFETs in a full-bridge configuration. A fully integrated charge
pump with external capacitors provides the gate voltage for the high-side output stages.
The Atmel ATA6823 supports low-speed LIN-data communication up to 20kBaud in compliance with LIN specification 2.0 using a built-in LIN transceiver. Protection features include
undervoltage/overvoltage detection and shutdown, overtemperature shutdown, and short
circuit detection of motor leads to battery voltage and to ground. Shoot-through protection
is guaranteed using a dead-time adjustment which can be set by hardware.
Features
● Header pins X1 to connect to LIN bus as well as power supply output and EN2
wake-up (see Table 1-1 on page 5)
● Microcontroller connector interface (See Table 1-2 on page 6)
● 4-mm banana plugs to connect power Supply BAT and GND
(see Figure 1-2 on page 3)
● Included power DC motor on-board, turn direction indicated by LEDs
● Vias M+ and M– to connect optional DC motor
● Optional connection of external motor h-bridge (See Figure 1-6 on page 7)
● Push-button EN2 to wake-up Atmel ATA6823
● Jumper VMODE to select VCC output voltage level
● Jumper RWD to select different WD resistors
● Shunt for DC motor current measurement
4961C-AUTO-06/15
1.
Application Board
The Atmel ATA6823 application board allows the running of a DC motor. The supply voltage is 8V to 18V, maximum power
of the DC motor is limited by the external H-bridge MOSFETs. No microcontroller is implemented on-board. It is possible to
control the motor either via an external microcontroller (with or without LIN bus), or directly (using the DIR and PWM pins).
Figure 1-1. Application Board
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ATA6823 [APPLICATION NOTE]
4961C–AUTO–06/15
X2
X1
GND
1
2
3
4
5
6
7
8
9
10
11
12
13
14
1
2
3
4
5
6
VCC
GND
/RESET
WD
TX
DIR
PWM
EN1
RX
DG3
DG2
DG1
AD0
PGND
VCC
GND
LIN
VBAT
VBATSW
EN2
PGND
C2
2.2μF
C1
10nF
R5B
n.b.
2.2μF
C3
C14
R7
10kΩ
330pF
R6
33kΩ
220nF
R5A
n.b.
1 2 3
JP1
RWD
C11
Q2
BC817-40
R1
470kΩ
R3
10kΩ
D1
BAS16
D3
220pF
LIN
GND
WD
RESET
CC
RWD
VINT
VMODE
1
C4
2.2μF
EN2
SW1
LL4248
FERRIT
C15
L2
1 2 3
JP2
VMODE
1kΩ
(Master)
R4
D2
GF1G
8
7
6
5
4
3
2
1
2
R2
+
C10
C6
24
17
18
19
20
21
22
23
S1
S1
S2
H2
L2
L1
H1
C13
220nF
VRES
PBAT
H1
S2
H2
VRES
CPHI
CPLO
VG
100nF
C12
470nF
470nF
C8
220μF/35V
C7
2.2μF
ATA6823
IC1
220μF/
35V
+
C9
100nF
C5A +
220μF/
35V
10kΩ
VBATSW
Q1
SUM110N06-05L
EN2
L1
7μH
L2
V+
VBAT
32
9
TX
31
VCO
11
PWM
12
EN1
10
DIR
30
PGND
29
L1
28
13
RX
27
14
DG3
25
PBAT
26
15
DG2
16
DG1
VSUP
1 JS2
2
3
1 JH2
2
3
XH2
XS2
XL2
X3
1 JL2
2
3
2
4
6
1 JL1
2
3
1 XH1
3 XS1
5 XL1
1 JS1
2
3
10nF
C24
Q5
SUM110N06-05L
R17
470kΩ
R16
10Ω
R14
10Ω
D4
MLED4
4.7nF
C20
R9
4.7Ω
R19
4.7Ω
0R01
R22
4.7nF
R18
4.7Ω
4.7nF
C23
1N4148 560Ω
C22
LED3
560Ω 1N4148
R24
D5
R23
M+
C19
4.7nF
C18
R8
4.7Ω
10nF
Q3
SUM110N06-05L
R11
470kΩ
R10
10Ω
1 JH1
2
3
C25
10nF
R13
10Ω
R20
470kΩ
R21
10Ω
R15
10Ω
R12
470kΩ
Q6
SUM110N06-05L
10nF
C21
Q4
SUM110N06-05L
PGND...MOTOR
PBAT...MOTOR
Figure 1-2. Atmel ATA6823 Application Board Schematic
ATA6823 [APPLICATION NOTE]
4961C–AUTO–06/15
3
Figure 1-3. Atmel ATA6823 Application Board Component Placement; Top Side, Top View
Figure 1-4. Atmel ATA6823 Application Board; Top Side, Top View
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ATA6823 [APPLICATION NOTE]
4961C–AUTO–06/15
Figure 1-5. Atmel ATA6823 Application Board; Bottom Side, Top View (as if PCB Were Transparent)
Table 1-1.
X1 LIN Header Pins
Pin
Symbol
1
VCC
Description
VCC regulator output, voltage level depends on jumper JP2 setting
2
GND
Ground for chip core
3
LIN
LIN bus terminal
4
VBAT
Atmel ATA6823 supply voltage
5
VBATSW
100 PMOS switch from VBAT
6
EN2
Enable input, 12V logic
ATA6823 [APPLICATION NOTE]
4961C–AUTO–06/15
5
Table 1-2.
X2 Microcontroller Interface Header Pins
Pin
Symbol
1
VCC
Out
2
GND
-
Ground for chip core
3
/RES
Out
Microcontroller reset
4
WD
In
Watchdog trigger signal
5
TX
In
Transmit signal to LIN bus from microcontroller
6
DIR
In
Defines the rotation direction of the motor
7
PWM
In
PWM input controls motor speed
8
EN1
In
Keeps the chip in ACTIVE mode via the microcontroller
9
RX
Out
Receive signal from LIN bus to microcontroller
10
DG3
Out
Diagnostic output 3
Description
VCC regulator output, voltage level depends on jumper JP2 setting
11
DG2
Out
Diagnostic output 2
12
DG1
Out
Diagnostic output 1
13
AD0
Out
Upper level of motor current shunt
14
PGND
Out
Lower level of motor current shunt, GND sense level
Table 1-3.
X3 ATA6823 Motor Bridge Interface
Pin
Symbol
1
XL2
Atmel ATA6823 pin 26, L2 output to control external H-bridge
2
XL1
Atmel ATA6823 pin 27, L1 output to control external H-bridge
3
XS2
Atmel ATA6823 pin 19, S2 output to control external H-bridge
4
XS1
Atmel ATA6823 pin 17, S1 output to control external H-bridge
5
XH2
Atmel ATA6823 pin 20, H2 output to control external H-bridge
6
XH1
Atmel ATA6823 pin 18, H1 output to control external H-bridge
Table 1-4.
Description
Jumper Settings
Jumper
6
Direction
Symbol
Description
Watchdog resistor selection
Upper position 2-3 selects R6 (default)
Lower position 1-2 selects R5A + R5B
R6 is implemented as 33k (customer specific, depending on watchdog requirements)
1
RWD
2
VMODE
3
JH2
Upper position 2-3 switches H2 to on-board H-bridge gate Q3 (default)
Lower position 1-2 switches H2 to external connector X3 pin XH2
4
JH1
See JH2
5
JS2
Upper position 2-3 switches S2 to on-board H-bridge motor M– (default)
Lower position, see JH2
6
JS1
Upper position 2-3 switches S2 to on-board H-bridge motor M+ (default)
Lower position, see JH2
7
JL2
See JH2
8
JL1
See JH2
VCC regulator output level
Upper position 2-3 = output level is 3.3V
Lower position 1-2, set to “1” = output level is 5V (default)
ATA6823 [APPLICATION NOTE]
4961C–AUTO–06/15
Table 1-5.
1.1
Push Button
Push
Button
Symbol
1
EN2
Function
It is possible to wake up the ATA6823 either by LIN or by push button EN2
Getting Started
To run the ATA6823 application board, a 8V to 18V supply voltage between VBAT and GND is necessary.
To check the board at start up, following voltages are measurable at 12.5V VBAT voltage.
After the power supply is switched on, a level of 5V is measurable at VINT and the header pin VCC; the VG voltage level is
12.5V and the charge pump voltage VRES is 26.5V. The voltage level at resistor RWD (R6, JP1) is 1.2V. The charge pump
capacity (C13) voltage level is 5V. The charge pump oscillator frequency is approximately 100kHz.
If the watchdog signal is not applied to the pin WD, the pin /RESET oscillates with a frequency around 7Hz.
It is not possible to activate the H-bridge without providing a watchdog.
1.2
External H-bridge
Figure 1-6. External H-bridge Connection
The application board offers the possibility of an external H-bridge connection (see Figure 1-6).
The external H-bridge can be supplied by the 4-mm banana plugs PBAT_MOTOR and PGND_MOTOR.
The gate driver and sense pins are available via header pin connector X3 (see Table 1-3 on page 6). To change between the
on-board H-bridge and the external H-bridge, jumpers JH2 to JL1 (see Table 1-4 on page 6) have to be changed to lower
position 1-2.
ATA6823 [APPLICATION NOTE]
4961C–AUTO–06/15
7
1.3
LIN Mode
Figure 1-7. LIN Master Option
According to LIN specification 2.0, resistor R4 is not necessary when using the Atmel® ATA6823 as slave. This is the default
at delivery.
To change the Atmel ATA6823 LIN from slave mode to master mode, complying with LIN specification 2.0, a 1k resistor
has to be inserted in place of R4, and reverse battery protection diode has to be inserted in place of D3.
1.4
Microcontroller Integration
To run the H-bridge, it is necessary to attend the Watchdog and Pace signal. To operate, a microcontroller can be connected
via the header pins X2 (see Table 1-2 on page 6). All pins which can be connected to the microcontroller are available on the
header pins X2:
● Voltage supply VCC
●
●
●
●
●
LIN interface
Watchdog
Motor control PWM and DIR
LIN transceiver
Diagnostic pins
The VCC voltage level can be chosen by the jumper VMODE (see Table 1-4 on page 6).
1.5
Current Shunt
Shunt R22 is available to monitor the H-bridge current. The sense lines AD0 and PGND (see Table 1-2 on page 6) of the
shunt can be connected to the AD converter of the microcontroller.
Figure 1-8. Watchdog Resistor Placement
1.6
Watchdog Resistor RWD
Upper jumper RWD position 2-3 selects the standard watchdog resister value R6 33k.
Optionally, the watchdog frequency can be changed via resistor R5, by setting jumper RWD to position 1-2. Either SMD
(R5A) or wired (R5B) resistors may be used.
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ATA6823 [APPLICATION NOTE]
4961C–AUTO–06/15
2.
Application Hints
2.1
Trigger Watchdog
To switch Atmel® ATA6823 into operating mode, it is necessary to apply a correct trigger signal to the pin WD. If
R6 = RWD = 33k, a square wave trigger signal of f = 70Hz is required. To adapt the resistor to other values, refer to the
datasheet for Atmel ATA6823, especially the section title Reset and Watchdog Management.
The trigger signal has no integrated debouncing circuit. It switches with a rising edge at pin WD.
Operating mode is shown by permanently high level at pin /RESET.
A wrong or missing trigger pulse generates a reset pulse with length of 2ms. VCC voltage lower than the reset threshold
generates a reset pulse for 68ms.
2.2
Enable
After power-on, the Atmel ATA6823 is in run mode. A falling edge at pin EN1 switches the device to standby mode.
Switching Atmel ATA6823 back to run mode is possible either by switching LIN to GND or by switching EN2 to VBAT.
EN2 can be switched up to VBAT. EN1 uses 5V logic and would be destroyed by switching to the VBAT level.
2.3
Wake-up Source Recognition
Diagnostic pin DG1 has a double assignment: Until the first watch dog pulse, DG1 shows the wake up source; a high level at
pin DG1 indicates that EN2 is the wake-up source, while a low level indicates LIN was wake-up source.
Table 2-1.
2.4
Diagnostic Pins
Signal
Description
DG1
Short circuit
DG2
Supply monitoring, charge pump
DG3
Overtemperature warning
Diagnostic Pins
There are three diagnostic pins available to detect errors (see Table 2-1 on page 9).
The Atmel ATA6823 has neither short-circuit shutdown nor short-circuit limitation. Short circuit is indicated, handling must be
done by the microcontroller.
While the outputs are switched on, the voltage levels between the active MOSFET sources and drains are monitored. If one
voltage level is higher than 4V, DG1 will be set to high. After switching the motor bridge, either by PWM or by DIR, the sense
monitoring is deactivated for 10µs. Otherwise inrush or switching currents will activate the DG1 warning.
Supply voltage breakdown at pin PBAT under the level of 5.6V is indicated by a high level at pin DG1, without any delay
time.
The intent is to monitor a dedicated H-bridge power supply.
An overvoltage or undervoltage condition at pin VBAT will be indicated by a high level at the diagnostic pin DG2. To
debounce, a 13-kHz low-pass filter is inserted.
Charge pump voltage lower than VVBAT + 4V will be indicated by DG2 set to high, with a debouncing time of 30µs.
If overtemperature of higher than 150°C is detected, the pin DG3 is set to high. The occurrence of overtemperature will be
latched until the next watchdog pulse.
If monitoring signals DG2 or DG3 indicate failure, the ATA6823 will switch off the motor bridge.
ATA6823 [APPLICATION NOTE]
4961C–AUTO–06/15
9
2.5
Motor Bridge OFF
When the PWM signal is set to low, both high-side MOSFETs are switched on to slow the motor down. Cruise Control
guarantees fly back currents over the contrary highside N-MOSFET.
2.6
Inrush Current
Switching a motor load on immediately to 100% duty cycle causes a voltage drop due to the inrush current. This drop
depends on the power supply installation. Depending on the level of voltage drop, the Atmel® ATA6823 detects short circuits
as described below. A short and proper connection between the power supply and application board is essential.
Use the PWM feature when supplying powerful motors and limiting their starting current.
2.7
Output Short Circuit
Five different short circuit conditions need to be considered. In the following comments, a static motor clamp will be the
clamp which is switched to VBAT. This high-side switch is not PWM controlled, it is permanently on. Dynamic motor clamp
will be the low-side clamp switch to GND, which is controlled by PWM.
1. Short between both motor clamps
In an ideal short circuit, 2 output switches and 1 inverse polarity protection switch are in serial. In this case, RdsON and
supply voltage higher than 12V short circuit will be detected by pin S1 or S2: One of the two drain source voltage
drops of the output FETs is higher than 4V and will switch DG1 on.
If the supply voltage is lower than 12V or the short circuit is not ideal (that is, the drain source voltage drop over both
output switches is lower than 4V each) the reservoir capacitor will be discharged. Voltage monitoring at PBAT will set
DG1. The PBAT voltage monitoring also will detect failure if PWM duty cycle time is shorter than 10µs, because 10µs
is the delay time until short circuit detection.
2.
Short between static motor clamp and ground
For an ideal short circuit and supply voltage higher than 8V, minimum one of the output drops is higher than 4V. The
sense pin S1 or S2 will switch the pin DG1.
In all other cases, PBAT monitoring will switch DG1, if PBAT falls below 5.6V.
3.
Short between dynamic clamp (PWM) and ground
For an ideal short circuit, supply voltage higher than 8V and ON duty cycle higher than 10µs, the sense pin S1 or S2
will switch the pin DG1.
For non-ideal short circuit or lower supply voltages, PBAT monitoring will switch DG1.
There is an 18V zener diode between Hx and Sx. In case of higher supply voltages and short between dynamic clamp
and GND, the charge pump capacity will be discharged over this 18V clamping structure. If voltage at VRES minus
voltage at PBAT is lower than 5V, after 30 µs, DG2 will be set and the output switches will be switched off.
4.
Short between dynamic clamp and supply pin PBAT after inverse polarity protection
For an ideal short circuit, supply voltage higher than 8V and ON duty cycle higher than 10µs causes a voltage drop
higher than 4V at least across output FET. The sense pins S1 or S2 will switch the pin DG1.
During other conditions, PBAT monitoring will switch DG1.
5.
Short between dynamic clamp and supply before inverse polarity protection
For ON duty cycle higher than 10µs, sense pin S1 or S2 will switch pin DG1.
A short circuit cannot be detected with the diagnostic pins of the Atmel ATA6823 for a duty cycle shorter than 10µs.
Usually the motor will not move, and the servo loop will signal deadlock.
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ATA6823 [APPLICATION NOTE]
4961C–AUTO–06/15
3.
Add-on Microcontroller Module to Generate WD and PWM
The WD and PWM signals are necessary to activate the Atmel ATA6823 H-bridge as shown in Table 1-2 on page 6.
Therefore, the microcontroller module (Figure 3-1 on page 12, Atmel ATA6823-DK2 V1.0), assembled with Atmel
ATmega88, is included. The module works with both Atmel ATA6823 digital supply voltages, 5V as well as 3.3V.
Table 3-1.
Add-on Module Operating Elements
Type
3.1
Name
Function
Push button
Ramp1
Start ramp release DG1 signals: short circuit
Push button
Ramp2
Stop ramp release DG2 signals: charge pump, overvoltage/undervoltage detection
Push button
Ramp3
Switch system into sleep mode
Switch
Direction
Left – Off – Right
Potentiometer
Speed
PWM frequency
Watchdog
The module generates a trigger signal of approximately fWD = 70Hz, which is required in case of the default watchdog
resistor RWD = R6 = 33k.
3.2
PWM
The module also provides the PWM signal with duty cycle from 0% to 100%, adjustable by speed potentiometer (see
Table 3-1). The PWM frequency of the example program is fPWM = 25kHz.
3.3
Operating Functions
The microcontroller module is turnable via operating elements as described in Table 3-1.
Two different operating modes are available:
1. Manual mode:
Rotation direction is selected using the direction switch, and the generated PWM frequency responds to the PWM
potentiometer.
2.
Automatic ramp mode:
Pressing push button Ramp1 causes a triangle-duty-cycle PWM curve to be generated. The low value is zero, the
maximum value is the set value of the speed potentiometer. The ramp will be stopped by pressing push button
Ramp2.
3.4
Sleep Mode
Push button Ramp3 is defined to switch Atmel® ATA6823 into standby mode. The microcontroller will no longer be supplied
with VCC voltage.
System wake-up can only be triggered by Atmel ATA6823.
Either ground level on the LIN bus or push button EN2 wakes up the Atmel ATA6823. The controller is supplied again and
begins to work.
3.5
Diagnosis
If a short circuit is indicated by diagnosis pin DG1, the microcontroller will switch off the H-bridge immediately. Turning it on
again is locked. Push button Ramp1 controls the unlock function.
DG2 voltage diagnosis also causes the switching off of the gate driver. To release, use push button Ramp2.
Overtemperature DG3 warning is indicated in the display, the H-bridge stops.
The overtemperature signaling is not latched, after cooling down the signal disappears, the H-bridge starts running again.
ATA6823 [APPLICATION NOTE]
4961C–AUTO–06/15
11
PB3
VCC
R2
10kΩ
ADC6
ADO
ISP
PC6
R1
39kΩ
PB5
VCC
PB4
DG2
DG1
ADO
XISP1
1
10
VCC
NRES
WD
TX
DIR
PWM
EN1
RX
DG3
1
X2
1
2 X2b
3
4
Figure 3-1. Add-on Atmel Atmega88 Module ATA6823-DK2 V1.0 for Generating WD and PWM
VCC
1
L1
100nF C2
BC817-40
17
18
PB5
19
ADC6
AVCC
8
PB7
PD5
PB6
PD2
C1
EN1
VCC
S4
100nF
PC3
PC2
PC1
PC0
PD3
PD3
PC4
R7
2.5kΩ
VCC
VCC
1
2
3
4
5
6
7
8
9
VSS
VDD
VEE
RS(SC)
R/W(SID)
E(SCLK)
D0(SOD)
D1
D2
LCD1
Display
C
A
RES
NC
D7(D3)
D6(D2)
D5(D1)
D4(D0)
D3
18
17
16
15
14
13
12
11
10
R4
18Ω
20
PD6
Q1
VCC
AREF
21
GND(21)
22
ADC7
PD1
1
R3
4.7kΩ
23
PD7
PD3
32
PD0
7
31
TX
PB0
VCC(6)
RX
PC6/NRST
6
NRES
30
PB1
GND(5)
29
PC6
PB4
PC5
5
10kΩ
For further information please refer to the datasheet for the Atmel ATA6823.
12
ATA6823 [APPLICATION NOTE]
4961C–AUTO–06/15
4
S2
1
PB2
VCC4
28
3
PB5
PC4
4
27
PC4
PB4
PB3
GND(3)
39kΩ
R5
1
C4
ADC6
3
R6
4
S3
PC3
PD4
VCC
PC2
2
PC3
PC0
24
26
PC0
PC1
25
PC2
3
100nF
C3 100nF
PC1
PB5
10μH
PB3
16
15
14
13
12
11
10
9
3
4
S1
PB4
PB3
DG3
DG2
DG1
DIR
WD
BWM
XXXXXX
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