IR21593SPBF International Rectifier, IR21593SPBF Datasheet - Page 18

• Manufacturer Part Number: IR21593SPBF
• Description: IC BALLAST CONTROL DIM 16-SOIC
• Manufacturer: International Rectifier
• Type: Ballast Controllerr

Specifications of IR21593SPBF

• Frequency: 30 ~ 230 kHz
• Current - Supply: 10mA
• Voltage - Supply: 12.5 V ~ 15.6 V
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 16-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Output: -
• Lead Free Status / Rohs Status: RoHS Compliant part

IR21592/IR21593
circuit measures the voltage at the CS pin and
compares it against the voltage at the IPH pin.
During the rising ignition ramp, the voltage at
the IPH pin is increased to 20% above its value
during preheat mode. When the voltage on the
CS pin exceeds this voltage, the voltage on the
IPH pin is decreased to VIPH Pre-Heat +10% and
the ignition detection circuit is then active (See
Figure 10). When the lamp ignites, the voltage on
the CS pin will then fall below the voltage on the
IPH pin and the IC enters DIM Mode and the phase
control loop is closed. In order for the ignition
detection circuit to function properly and for the IC
to enter DIM mode, the voltage on the CS pin must
first rise above VIPH Pre-Heat + 20% during the
ignition ramp to activate the circuit, and then
decrease below VIPH Pre-Heat +10% when the lamp
ignites.
Ignition-to-Dim (IGN-to-DIM)
When the IR21592/IR21593 enters dim mode, the
phase control loop is closed and the phase of the
18
V
CS
IPH
Figure 10, IR21592/IR21593 ignition detection.
V
PH
IPH
+ 20%
IGN
( S ) & ( PbF )
DIM
V
IPH
+ 10%
load current is regulated against the user control
input on pin DIM. To control the rate at which the
dim setting changes from maximum brightness
to the user setting (IGN-TO-DIM time, Figure 11),
pin DIM is connected internally to pin CPH when
the IR21592/IR21593 enters DIM mode. The
resistor on pin DIM (RDIM) discharges the
capacitor on pin CPH down to the user dim
setting. The resistor can be selected for a fast
time constant to minimize the amount of flash
visible over the lamp just after ignition, or, a
long time constant such that the brightness
ramps down smoothly to the user setting. Should
the ignition-to-dim time be too fast, however, the
loop can respond faster than the ionization
constant of the lamp (milliseconds) causing the
VCO to over-shoot. This can result in a
frequency that is higher than the minimum
brightness frequency and can extinguish the
lamp. The capacitor on pin CPH serves multiple
functions by setting the preheat time, the travel
rate just after ignition (together with resistor
RDIM), and, serving as a filter capacitor on pin
V
5.1V
V
Figure 11, IR21592/IR21593 ignition timing diagram.
V
CPH
VCO
DIM
PH
IGN
R
TIME CONSTANT
DIM
& C
DIM
IGN-TO-DIM
www.irf.com
TPH
TIME
t
t