IRS2573D
www.irf.com © 2009 International Rectifier
15
Application Information and Additional Details
Information regarding the following topics is included as subsections within this section of the datasheet.
• IGBT/MOSFET Gate Drive
• Undervoltage Lockout Protection
• General Mode
• Ignition Timer
• Full-Bridge Control
• Buck Control
• Constant Power Control
• Current Limitation Control
• Over Voltage Fault Counter
• Under Voltage Fault Counter
• Fast Transient Under-Voltage Fault Counter
• Good Counter
• Fault Reset
• PCB Layout Tips
• Additional Documentation
IGBT/MOSFET Gate Drive
The IRS2573D HVICs are designed to drive up to six MOSFET or IGBT power devices. Figures 1 and 2 illustrate
several parameters associated with the gate drive functionality of the HVIC. The output current of the HVIC, used
to drive the gate of the power switch, is defined as I
O
. The voltage that drives the gate of the external power
switch is defined as V
HO
for the high-side power switch and V
LO
for the low-side power switch; this parameter is
sometimes generically called V
OUT
and in this case does not differentiate between the high-side or low-side output
voltage.
V
S
(or COM)
HO
(or LO)
V
B
(or V
CC
)
I
O+
V
HO
(or V
LO
)
+
-
V
S
(or COM)
HO
(or LO)
V
B
(or V
CC
)
I
O-
Figure 1: HVIC sourcing current Figure 2: HVIC sinking current
Undervoltage Lock-Out
The under-voltage lockout mode (UVLO) is defined as the state the IC is in when VCC is below the turn-on
threshold of the IC. The IC is designed to maintain an ultra-low supply current during UVLO mode of 150uA for
reducing power losses across the external start-up resistor, and, to guarantee the IC is fully functional before the
buck high-side and full-bridge high and low-side output drivers are activated. The external capacitor from VCC
to COM is charged by a current flowing from the rectified AC line or DC bus through an external supply resistor
minus the micro-power start-up current drawn by the IC. The external start-up resistor is chosen so that VCC
exceeds the IC turn-on threshold at the desired AC line turn-on voltage for the ballast. Once the capacitor voltage
