IR21571S International Rectifier, IR21571S Datasheet - Page 8

• Manufacturer Part Number: IR21571S
• Description: IC BALLAST CONTROL 16-SOIC
• Manufacturer: International Rectifier
• Type: Ballast Controllerr

Specifications of IR21571S

• Frequency: 45.5 ~ 50.5 kHz
• Current - Supply: 5.5mA
• Current - Output: 500mA
• Voltage - Supply: 11.4 V ~ 15.6 V
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 16-SOIC (3.9mm Width)
• Package: 16-lead SOIC Narrow
• Circuit: Fluorescent Ballast IC
• Offset Voltage (v): 625
• Output Source Current Min (ma): 250
• Output Sink Current Min (ma): 400
• Vcc Range (v): 10-25V with UVLO
• Output Voltage Min (v): 10
• Output Voltage Max (v): 25
• Special Ic: Fully Integrated
• Pbf: PbF Option Available
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: *IR21571S

Component selection and placement on the pc
board is extremely important when using power
control ICs. V
to the IC terminals as possible with a low ESR/ESL
capacitor, as shown in Figure 1 below.
IR21571 (S) & (PbF)
8
IR21571
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., 10 F) placed immediately adjacent
to the V
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.
arrangement, the internal 15.6V zener clamp diode
from V
supply voltage.
Figure 1: Supply bypassing PCB layout example
Supply Bypassing and PC Board
pin 1
CC
CC
Description of Operation & Component Selection Tips
CC
to COM will determine the steady state IC
and COM terminals will work well.
should be bypassed to COM as close
Layout Rules
C
VCC
(surface mount)
C
With this type of supply
BOOT
C
(surface mount)
VCC
D
(through hole)
Boot
(surface mount)
This connection technique prevents high current
ground loops from interfering with the sensitive timing
component operation, and allows the entire control
circuit to reject common-mode noise due to output
switching.
Both the low power control circuitry and low side
gate driver output stage grounds return to this lead
within the IC. The COM lead 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
be connected directly to the IC COM lead, and not
via separate traces or jumpers to other ground traces
on the board.
Figure 2: COM lead connection PCB layout example
components
V
Connecting the IC Ground (COM)
timing
BUS
return
IR21571
to the Power Ground
pin 1
CC
decoupling capacitor should
C
VCC
(surface mount)
C
VCC
www.irf.com
R
(through hole)
CS
(through hole)