ST AN994 APPLICATION NOTE
AN994
Application note
L638xE application guide
Introduction
STMicroelectronics’ L638xE is a versatile, high-voltage gate driver family of devices.
Developed using BCD offline technology, the L6384E, L6385E, L6386E, L6387E and
L6388E devices can operate with high voltage rails up to 600 V. The gate drivers provide all
the functions and current capability necessary for high- and low-side power MOSFETs and
IGBTs.
The devices can be used in all types of applications where high-voltage shifted control is
necessary; they have a relatively high driver current capability and are provided with an
internal patented circuitry that replaces the external bootstrap diode. This feature is
achieved by means of a high voltage DMOS, synchronously driven with the low-side gate
driver.
February 2009 Rev 7 1/25
www.st.com
Contents AN994
Contents
1 L6384E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2 L6385E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3 L6386E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4 L6387E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5 L6388E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
6 Bootstrap driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
6.1 C
selection and charging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
BOOT
7 Application examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
8 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2/25
AN994 List of figures
List of figures
Figure 1. L6384E internal block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Figure 2. L6384E - schematic diagram of the evaluation circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Figure 3. L6384E - PCB and component layout of the evaluation circuit. . . . . . . . . . . . . . . . . . . . . . . 6
Figure 4. L6385E - internal block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Figure 5. L6385E - schematic diagram of the evaluation circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Figure 6. L6385E - PCB and component layout of the evaluation circuit. . . . . . . . . . . . . . . . . . . . . . . 9
Figure 7. L6386E - internal block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Figure 8. L6386E - schematic diagram of the evaluation circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Figure 9. L6386E - PCB and component layout of the evaluation circuit. . . . . . . . . . . . . . . . . . . . . . 12
Figure 10. L6387E - internal block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Figure 11. L6388E internal block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Figure 12. External bootstrap diode: principle schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Figure 13. Internal bootstrap diode: principle schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Figure 14. External charge pump. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Figure 15. L6384E µC 3-phase motor control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Figure 16. L6384E dimmable lamp ballast. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Figure 17. L6384E half bridge converter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Figure 18. L6385E horizontal deflection stage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Figure 19. L6385E 2-switch forward converter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Figure 20. L6385E asymmetrical half bridge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Figure 21. L6386E h-bridge with cycle-by-cycle control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
3/25
L6384E AN994
1 L6384E
The L6384E (depicted in Figure 1) is a half-bridge driver with an externally-adjustable dead
time and shut-down function. To disable the driver, the control pin (DT/SD at pin 3) must be
pulled down to below 0.5 V. The dead time can be set from 0.5 µs to 2.7 µs by placing a
resistor between pin 3 and ground. Available in both Minidip and SO-8 packages, this driver
can be used in motor controls, resonant converters and lighting applications. Figure 2 and
Figure 3 show the schematic diagram of the evaluation circuit and the layout of the test PCB.
Table 1. L6384E pin description
N. Name Typ. Function
1 IN
2 V
3 DT/SD I
4 GND Ground.
5 LVG O
6 OUT O
(1)
I Logic input. In phase with HVG and in opposition to LVG. Compatible with the VCC voltage.
CC
Supply input voltage. Includes an internal clamp (typically 15.6 V). Also has a UVLO feature
(typical threshold value V
ccth1
= 12 V, V
High impedance pin with double function. When pulled to a voltage lower than V
0.5 V) the device is shut down. A voltage higher than V
ccth2
= 10 V).
(typically
sets the dead time between the high
dt
dt
side and low side gate driver. The dead time value can be set by forcing a certain voltage level on
the pin or by connecting a resistor between pin 3 and ground. Care must be taken to avoid spikes
on pin 3 that could cause an undesired shut down of the IC. For this reason, the connection of the
components between pin 3 and ground must be as short as possible. This pin cannot be left
floating for the same reason. The pin must not be pulled through a low impedance to V
because of the drop on the current source that feeds R
.
dt
Low-side driver output. The output stage can deliver a 400 mA source and a 650 mA sink (typical
values). The circuit guarantees 0.3 V maximum on the pin (at I
= 10 mA) with V
sink
CC
lower than the turn-on threshold. This removes the need for the bleeder resistor connected
between the gate and the source of the external MOSFET normally used to hold the pin low. The
gate driver ensures low impedance in SD conditions as well.
Upper driver floating reference. Attention should be paid to the layout design of the power stage
so as to limit below-ground spikes on this pin.
CC
> 3 V and
High-side driver output. The output stage can deliver a 400 mA source and a 650 mA sink (typical
values). The circuit guarantees 0.3 V maximum between this pin and Vout (at I
> 3 V and lower than the turn-on threshold. This removes the need for the bleeder resistor
7HVG O
V
CC
connected between the gate and the source of the external MOSFET normally used to hold the
pin low. The gate driver ensures low impedance in SD conditions as well.
Bootstrap supply voltage. This is the upper driver floating supply. The bootstrap capacitor
8V
BOOT
connected between this pin and pin 6 can be fed by an internal structure named "bootstrap
driver" (a patented structure). This structure can replace the external bootstrap diode.
1. The pull-down internal resistor is typically some hundred kΩs.
4/25
= 10 mA) with
sink
AN994 L6384E
Figure 1. L6384E internal block diagram
H.V.
V
CC
2
BOOTSTRAP DRIVER
V
8
BOOT
V
CC
HVG
DRIVER
DT/SD
UV
DETECTION
R S
1
IN
V
CC
Idt
3
Vthi
DEAD
TIME
LOGIC
LEVEL
SHIFTER
LVG
DRIVER
Figure 2. L6384E - schematic diagram of the evaluation circuit
E
C
BOOT
HVG
7
OUT
6
LVG
5
GND
4
LOAD
AM03415v1
5/25
L6384E AN994
Figure 3. L6384E - PCB and component layout of the evaluation circuit
Top view
Bottom view
AM03413v1
6/25
AN994 L6385E
2 L6385E
The L6385E (shown in Figure 4) is a high- and low-side configurable driver. It can control
the high- and low-side outputs (HVG and LVG) seperately, through the two related logic
inputs HIN and LIN. This device is provided with an undervoltage detection function in both
the low voltage V
packages, this driver has been specifically designed for power supplies and motion control
applications.
Figure 5 and Figure 6 show the schematic diagram of the evaluation circuit and the layout of
the relevant PCB.
Table 2. L6385E pin description
N. Name Type Function
1 LIN
2 HIN
3
4 GND Ground.
5 LVG O
6 OUT O
7 HVG O
(1)
I Low-side driver logic input. Compatible with the VCC voltage (V
(1)
I High-side driver logic input. Compatible with the VCC voltage (V
VCC Supply input voltage with UVLO (typically V
Low-side driver output. The output stage can deliver a 400 mA source and a 650 mA sink
(typical values). The circuit guarantees 0.3 V maximum on the pin (at Isink = 10 mA) with
V
CC
resistor connected between the gate and the source of the external MOSFET normally
used to hold the pin low. The gate driver ensures low impedance in SD conditions as well.
High-side driver floating reference. Attention should be paid to the layout design of the
power stage so as to limit below-ground spikes on this pin.
High-side driver output. The output stage can deliver a 400 mA source and a 650 mA sink
(typical values). The circuit guarantees 0.3 V maximum between this pin and Vout (at Isink
= 10 mA) with V
the bleeder resistor connected between the gate and the source of the external MOSFET
normally used to hold the pin low.
supply and high-voltage bootstrapped supply. Delivered in 8-pin
CC
ccth1
= 9.6 V, V
ccth2
= 1.5 V, V
il Max
= 1.5 V, V
il Max
= 8.3 V).
ih Min
ih Min
= 3.6 V)
= 3.6 V)
> 3 V and lower than the turn-on threshold. This removes the need for the bleeder
> 3 V and lower than the turn-on threshold. This removes the need for
CC
Bootstrap supply voltage. This is the floating supply of the high-side driver. Includes a
8 V
BOOT
UVLO function (typically, V
between this pin and pin 6 can be fed by an internal structure named "bootstrap driver" (a
BSth1
patented structure). This structure can replace the external bootstrap diode.
1. The pull-down internal resistor is typically some hundred kΩs.
= 9.5 V, V
= 8.2 V). The bootstrap capacitor connected
BSth2
7/25
L6385E AN994
Figure 4. L6385E - internal block diagram
Figure 5. L6385E - schematic diagram of the evaluation circuit
E
8/25
Loading...