IR21571S International Rectifier, IR21571S Datasheet - Page 11

• 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

The Preheat Time is programmed by means of the
preheat capacitor, C
source, and an internal threshold on the C
4.0V, according to the following formula:
At the end of the Preheat Time, the internal, open-
drain transistor holding the R
off, and the voltage on this lead charges exponentially
up to the R
Mode, the output frequency exponentially decays to
a minimum value. The rate of decay of this frequency
is a function of the R
the Ignition Ramp Mode ends when the voltage on
the C
is always 1/4th as long as the preheat time.
When the C
transistor on the RUN lead turns on, and the external
R
The Run Mode operating frequency is therefore a
function of the parallel combination of R
and this means that the operating power of the lamp
can be programmed by means of R
www.irf.com
RUN
PH
resistor is then in parallel with the R
Figure 7: Lamp filament voltage during the
lead reaches 5.15V, the Ignition Ramp Mode
preheat, ignition ramp and run modes.
T
lead potential. During this Ignition Ramp
PH
C
t
PH
PH
lead reaches 5.15V, an open-drain
=
Preheat
4.7E6
213E
PH
PH
* C
, an internal 1 A current
9 -
PH
C
Ignition
PH
Ramp
time constant. Because
PH
t
PH
,
lead to ground turns
or
RUN
Run
.
RUN
PH
T
resistor.
and R
lead of
T
,
The following graphs, Figures 8 and 9, illustrate the
relationship between the effective R
the parallel combination of resistors which programs
the C
frequency.
FREQ
(KHz)
FREQ
(KHz)
Figure 8: fosc versus effective R
Figure 9: fosc versus effective R
150
100
50
0
0
250
200
150
100
T
50
0
capacitor charging current) and the operating
0
5
5
IR21571 (S) & (PbF)
10
10
15
15
RT (K ohms)
RT (K ohms)
20
20
25
T
T
25
(t
(t
CT=220pF, RDT=5.6K
CT=470pF, RDT=2.7K
CT=1nF, RDT=1.2K
CT=220pF,RDT=11K
CT=470pF,RDT=6.2K
CT=1nF,RDT=3K
DEAD
DEAD
T
30
resistance (i.e.,
30
= 2.0 usec)
= 1.0 usec)
35
35
40
40
11