L6388ED STMicroelectronics, L6388ED Datasheet - Page 5

• Manufacturer Part Number: L6388ED
• Description: IC DRIVER HI/LO SIDE HV 8-SOIC
• Manufacturer: STMicroelectronics
• Type: High Side/Low Sider

Specifications of L6388ED

• Configuration: High and Low Side, Synchronous
• Input Type: Non-Inverting
• Delay Time: 225ns
• Current - Peak: 400mA
• Number Of Configurations: 1
• Number Of Outputs: 2
• High Side Voltage - Max (bootstrap): 600V
• Voltage - Supply: 17V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Product: Half-Bridge Drivers
• Rise Time: 100 ns
• Fall Time: 80 ns
• Maximum Power Dissipation: 750 mW
• Maximum Operating Temperature: + 125 C
• Mounting Style: SMD/SMT
• Bridge Type: Half Bridge
• Minimum Operating Temperature: - 45 C
• Number Of Drivers: 2
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

3
Input logic is provided with an interlocking circuitry which avoids the two outputs (LVG, HVG) to be active at the
same time when both the logic input pins (LIN, HIN) are at a high logic level. In addition, to prevent cross con-
duction of the external MOSFETs, after each output is turned-off the other output cannot be turned-on before a
certain amount of time (DT) (see Figure 4).
Figure 6. Typical Rise and Fall Times vs. Load
3.1 BOOTSTRAP DRIVER
A bootstrap circuitry is needed to supply the high voltage section. This function is normally accomplished by a
high voltage fast recovery diode (fig. 8a). In the L6388 a patented integrated structure replaces the external di-
ode. It is realized by a high voltage DMOS, driven synchronously with the low side driver (LVG), with in series
a diode, as shown in fig. 8b
An internal charge pump (fig. 8b) provides the DMOS driving voltage .
The diode connected in series to the DMOS has been added to avoid undesirable turn on of it.
3.2 CBOOT selection and charging
To choose the proper C
C
The ratio between the capacitors C
It has to be:
e.g.: if Q
If HVG has to be supplied for a long time, the CBOOT selection has to take into account also the leakage losses.
e.g.: HVG steady state consumption is lower than 200µA, so if HVG T
C
The internal bootstrap driver gives great advantages: the external fast recovery diode can be avoided (it usually
has great leakage current). This structure can work only if V
the LVG is on. The charging time (T
(nsec)
EXT
EXT
time
250
200
150
100
50
0
INPUT LOGIC
. This charge on a 1µF capacitor means a voltage drop of 1V.
is related to the MOS total gate charge :
For both high and low side buffers @25˚C Tamb
0
gate
Capacitance
is 30nC and V
1
2
BOOT
gate
3
value the external MOS can be seen as an equivalent capacitor. This capacitor
is 10V, C
4
EXT
charge
T r
T f
and C
EXT
) of the C
5
D99IN1054
is 3nF. With C
BOOT
C (nF)
CBOOT>>>CEXT
C
EXT
is proportional to the cyclical voltage loss .
BOOT
=
Q
-------------- -
V
is the time in which both conditions are fulfilled and it
Figure 7. Quiescent Current vs. Supply
gate
gate
BOOT
OUT
(µA)
10
10
10
10
Iq
4
3
2
is close to GND (or lower) and in the meanwhile
0
= 100nF the drop would be 300mV.
2
Voltage
ON
is 5ms, CBOOT has to supply 1µC to
4
6
8
10
12
14
D99IN1055
16 V
L6388
S
5/11
(V)