ST L638E Series User guide

February 2009 Rev 7 1/25
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.
www.st.com

Contents AN994
2/25
Contents
1 L6384E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2 L6385E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3 L6386E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4 L6387E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5 L6388E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
6 Bootstrap driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
6.1 CBOOT selection and charging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
7 Application examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
8 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

AN994 List of figures
3/25
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

L6384E AN994
4/25
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(1) I Logic input. In phase with HVG and in opposition to LVG. Compatible with the VCC voltage.
2 VCC Supply input voltage. Includes an internal clamp (typically 15.6 V). Also has a UVLO feature
(typical threshold value Vccth1 = 12 V, Vccth2 = 10 V).
3 DT/SD I
High impedance pin with double function. When pulled to a voltage lower than Vdt (typically
0.5 V) the device is shut down. A voltage higher than Vdt sets the dead time between the high
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 VCC
because of the drop on the current source that feeds Rdt.
4 GND Ground.
5 LVG O
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 VCC > 3 V and
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.
6 OUT O 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.
7HVG O
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
VCC > 3 V and 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.
8V
BOOT
Bootstrap supply voltage. This is the upper driver floating supply. The bootstrap capacitor
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.

AN994 L6384E
5/25
Figure 1. L6384E internal block diagram
Figure 2. L6384E - schematic diagram of the evaluation circuit
AM03415v1
LOGIC
UV
DETECTION
LEVEL
SHIFTER
RS
V
CC
LVG
DRIVER
V
CC
IN
DT/SD
V
BOOT
HVG
DRIVER HVG
H.V.
LOAD
OUT
LVG
GND
DEAD
TIME
V
CC
Idt
Vthi
BOOTSTRAP DRIVER
C
BOOT
4
3
5
6
7
8
1
2
E

L6384E AN994
6/25
Figure 3. L6384E - PCB and component layout of the evaluation circuit
AM03413v1
Top view
Bottom view

AN994 L6385E
7/25
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 VCC supply and high-voltage bootstrapped supply. Delivered in 8-pin
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
(1) I Low-side driver logic input. Compatible with the VCC voltage (Vil Max = 1.5 V, Vih Min = 3.6 V)
2 HIN
(1) I High-side driver logic input. Compatible with the VCC voltage (Vil Max = 1.5 V, Vih Min = 3.6 V)
3 VCC Supply input voltage with UVLO (typically Vccth1 = 9.6 V, Vccth2 = 8.3 V).
4 GND Ground.
5 LVG O
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
VCC > 3 V and 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.
6 OUT O
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.
7 HVG O
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 VCC > 3 V and 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.
8 VBOOT
Bootstrap supply voltage. This is the floating supply of the high-side driver. Includes a
UVLO function (typically, VBSth1 = 9.5 V, VBSth2= 8.2 V). The bootstrap capacitor 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.

L6385E AN994
8/25
Figure 4. L6385E - internal block diagram
Figure 5. L6385E - schematic diagram of the evaluation circuit
E

AN994 L6385E
9/25
Figure 6. L6385E - PCB and component layout of the evaluation circuit
AM03414v1
Top view
Bottom view

L6386E AN994
10/25
3 L6386E
The L6386E (shown in Figure 7) is a configurable driver based on the structure of the
L6385E, with added functions. This device is available in DIP14 or SO-14 packages.
The added shutdown function (active low) and the current sense comparator (0.5-V
threshold) with diagnostic output, make this device particularly suitable for motion control
applications with cycle-by-cycle current feedback. The DIAG and CIN pins can be used to
stop the device (by acting on the SD pin). Figure 8 and Figure 9 show the schematic
diagram of the evaluation circuit and the layout of the relevant PCB.
Table 3. L6386E pin description
N. Name Type Function
1 LIN
(1) I Lower driver logic input. Compatible with the VCC voltage (Vil Max = 1.5 V, Vih Min = 3.6 V).
2 SD
(1) I Shut-down logic input. Compatible with the VCC voltage. If it needs to be pulled up, the
suggested resistor value is 5 to 10 kΩ. (Vil Max = 1.5 V, Vih Min = 3.6 V).
3 HIN
(1) I Low-side driver logic input. Compatible with the VCC voltage.
4 VCC Supply input voltage with UVLO (typically Vccth1 = 12 V, Vccth2 = 10 V).
5 DIAG O Diagnostic output: open drain.
6 CIN I Comparator input.
7 SGND Ground reference for logic signals.
8 PGND Power ground reference for the low voltage gate driver.
9 LVG O
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
VCC > 3 V and 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.
10, 11 N.C. Not connected.
12 OUT O
High-side floating driver. Attention should be paid to the layout design of the power stage
so as to limit below-ground spikes on this pin.
13 HVG O
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 VCC > 3 V and 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.
14 VBOOT
Bootstrapped supply voltage. This is the floating supply of the high-side driver. Includes a
UVLO function (typically, VBth1 = 11.9V, VBth2 = 9.9 V). The bootstrap capacitor connected
between this pin and pin 12 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.