MC33883 查看數據表（PDF） - Motorola => Freescale
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MC33883 Datasheet PDF : 11 Pages
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DEVICE DESCRIPTION
Driver Characteristics
Turn-On:
For turn-on the current required to charge the gate source
capacitor Ciss in the specified time can be calculated as follows:
Peak Current for Rise/Fall Time (tr) and a typical PowerMos-
FET Gate Charge Qg
IP = Qg/tr = 80nC/80 ns ≈ 1.0 A
Turn-Off:
The peak current for turn-off can be obtained in the same
way as for turn-on. In addition to the dynamically current,
required to turn-off or turn-on the FET, various application
related switching scenarios have to be considered:
The output driver sources a peak current of up to 1A for
200ns to turn on the gate. After 200ns, 100mA is provided
continuously to maintain the gate charged.
The output driver sinks a peak current of up to 1A for 200ns
to turn off the gate.
After 200ns, 100mA are sinked continuously to maintain the
gate discharged.
In order to withstand high dV/dt spikes a low resistive path
between gate and source is implemented during the off
state.
Figure 3:
Flyback Spike charge LS-
Gate via Crss
Charge Current Irss up to 2.0
A! Uncontrolled Turn-On of
Low Side FET
Flyback Spike pull
down HS-Drain VGS
Increase Delayed
Turn-Off of High Side
FET
Flyback Spike charge
LS-Gate via Crss
Charge Current Irss up
to 2.0 A! Delayed Turn-
Off of Low Side FET
Flyback Spike pull down
HS-Drain VGS Increase
Uncontrolled Turn-On of
High Side FET
Crss
g_hs
VGATE
Ciss
Irss Crss
g_ls
OFF
Ciss
VBAT
Crss
g_hs
L1 ILOAD Ciss
Crss
g_ls
OFF
Ciss
VBAT
Crss
OFF
g_hs
L1 ILOAD
Ciss
Crss
g_ls
Ciss
VBAT
Crss
OFF
VGATE
-VDRN
g_hs
L1 ILOAD
Ciss
Crss
g_ls
Ciss
VBAT
L1 ILOAD
Driver Requirement: Low
Resistive Gate-Source
Path during OFF-State
Driver Requirement:
Low Resistive Gate
Source Path during OFF-
State. High Peak Sink
Current Capab.
Driver Requirement:
High Peak Sink Current Capab.
Driver Requirement: Low
Resistive Gate-Source
Path during OFF-State
MC33883
Page 7 of 11
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