RYC9901 Tyco Electronics, RYC9901 Datasheet - Page 10

• Manufacturer Part Number: RYC9901
• Description: IC, LED DRIVER, BOOST, SOT-23-6
• Manufacturer: Tyco Electronics

Specifications of RYC9901

• No. Of Outputs: 1
• Output Current: 1.9A
• Output Voltage: 25V
• Input Voltage: 1.9V To 5.5V
• Dimming Control Type: PWM / Analog
• Operating Temperature Range: -40°C To +85°C
• Topology: Boost
• Output Power: 700 mWatts
• Switching Frequency: 85 KHz
• Mounting Style: SMD/SMT
• Package / Case: SOT-23-6
• Duty Cycle (max): 75 %
• Number Of Outputs: 2
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

RYC9901
Multi-LED Boost
In the case of a high voltage power source, the
inductor may be attached directly to a voltage up to
about 25V, subject to the limitations mentioned above
about the nature of non-isolated flybacks. The small
current needed for the VCC pin can then be generated
by a low-power resistor and a zener from the high
voltage source. A 5V supply is recommended.
In the case of a voltage power source below the UVLO
of the IC, the inductor may still be operated from the
power source. All that is required is that the small
current required by the RYC9901 be made available
from a higher voltage supply; a 5V supply is
recommended.
Open String
If the output of the RYC9901 device is open, as might
happen if the LED string fails open, the energy stored
in the inductor each cycle is dissipated in the power
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© 2005 Tyco Electronics Corporation.
device of the IC. Although not recommended, the
RYC9901 device is rated to take this avalanche
energy, which will not damage it, for up to one minute.
If the energy is sufficiently high, the RYC9901 device
may go into thermal shutdown. After cooling off, it will
begin operation again. This cycling should not damage
the IC. The output voltage in open string may rise as
high as 40V, and the output capacitor and diode
should be rated to withstand this voltage in this mode.
Alternatively a 30V zener may be placed in parallel
with the output cap.
Thermal Shutdown
If the RYC9901 device die becomes excessively hot,
the IC should shut itself down. It will then resume
normal operation after cooling down sufficiently.
www.tycopowercomponents.com
Document: SCD 25493
Status: Released
Rev.: D
Rev Date: March 8, 2005
Raychem
Power Management ICs
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