IRS21571DSPBF International Rectifier, IRS21571DSPBF Datasheet - Page 14

• Manufacturer Part Number: IRS21571DSPBF
• Description: IC BALLAST CTRL 600V 16-SOIC
• Manufacturer: International Rectifier
• Type: Ballast Controllerr

Specifications of IRS21571DSPBF

• Frequency: 43.7 ~ 48.3 kHz
• Current - Supply: 10mA
• Current - Output: 180mA
• Voltage - Supply: 11.5 V ~ 15.6 V
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 16-SOIC (0.154", 3.90mm Width)
• Package: 16-lead SOIC Narrow
• Circuit: Fluorescent Ballast IC
• Offset Voltage (v): 600
• Output Source Current Min (ma): 180
• Output Sink Current Min (ma): 260
• Pbf: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

www.irf.com
Application Information and Additional Details
Supply Bypassing and PCB Layout Rules
Component selection and placement on the pc board is extremely important when using power control ICs. V
should be bypassed to COM as close to the IC terminals as possible with a low ESR/ESL capacitor, as shown in
Figure 1 below.
A rule of thumb for the value of this bypass capacitor is to keep its minimum value at least 2500 times the value of
the total input capacitance (Ciss) of the power transistors being driven. This decoupling capacitor can be split
between a higher valued electrolytic type and a lower valued ceramic type connected in parallel, although a good
quality electrolytic (e.g., 10μF) placed immediately adjacent to the VCC and COM terminals will work well.
In a typical application circuit, the supply voltage to the IC is normally derived by means of a high value startup
resistor (1/4W) from the rectified line voltage, in combination with a charge pump from the output of the half-
bridge. With this type of supply arrangement, the internal 15.6V zener clamp diode from VCC to COM will
determine the steady state IC supply voltage.
Connecting the IC Ground (COM) to the Power Ground
Both the low power control circuitry and low side gate driver output stage grounds return to this pin within the IC.
The COM pin should be connected to the bottom terminal of the current sense resistor in the source of the low
side power MOSFET using an individual pc board trace, as shown in Figure 2. In addition, the ground return path
of the timing components and V
via separate traces or jumpers to other ground traces on the board.
Figure 2: COM pin connection PCB layout example
CC
Figure 1: Supply bypassing PCB layout example
components
V
decoupling capacitor should be connected directly to the IC COM pin, and not
timing
BUS
return
IR21571
pin 1
IR21571
pin 1
C
VCC
14
(surface mount)
C
BOOT
C
(surface mount)
VCC
C
(through hole)
VCC
(surface mount)
C
VCC
R
(through hole)
CS
(through hole)
© 2008 International Rectifier
IRS21571D
CC