TB62737FPG Toshiba, TB62737FPG Datasheet - Page 6

• Manufacturer Part Number: TB62737FPG
• Manufacturer: Toshiba

Specifications of TB62737FPG

• Package: SON6
• Supply Voltage: 2.8V to 5.5V
• # Leds Supported: 2 to 6 LEDs in series
• Sw Frequency: 1.1MHz
• Led Current Accuracy: ±5.23% (max)
• Protection Feature: Output overvoltage protection
• Other Features & Functions: Analog dimming
• Rohs Compatible Product(s) (#): -

2) Input PWM signal to SHDN terminal
I
[Notice]
F
can be adjusted with PWM signal by inputting it to SHDN terminal.
<<Minimum ON-time of PWM signal input>>
<<PWM input signal>>
<<PWM signal frequency>>
<<Constant number of external condenser>>
<<Rush current in inputting>>
<<Current value in Control with PWM: Ideal Equation>>
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•
•
•
•
•
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Set the minimum ON-time or OFF-time 33 μs or more in inputting the PWM signal.
Set the Duty ratio satisfying the condition above.
The recommended PWM signal frequency is from 100 Hz to 10 kHz. There is a possibility to arise the
audible frequency in mounting to the board because it is within the auditory area.
To reduce the fluctuation of input current and increase the accuracy of brightness, the values that C
4.7 (μF) or more , C
When the PWM signal is off, the time to drain C
the actual value is little different from the theoretical value.
Set the amplitude of PWM signal within the range of SHDN terminal specification.
In case dimming by inputting the PWM signal to the SHDN terminal, this IC turns on and off repeatedly.
And the rush current, which provides the charge to C
condenser.
1 ms (1 kHz) = 100%
Ex) In case PWM Frequency is 1 kHz,
F I
[ ]
mA
1 kHz is 1 ms (PWM width = 100%) and it takes 10 μs per 1%.
To set the pulse width 33 μs or more, necessary ON-or-OFF-time is calculated below.
Finally, the Duty Ratio can be set in range of 3.3% to 96.7%.
=
33 μs ÷ 10 μs = 3.3% (Under the condition that 10 μs equals 1%.)
325
[ ]
mV
R
2
SENS
= 0.1 (μF) or less are recommended.
×
ONDuty
[ ]
Ω
[ ]
%
Set OFF-time
Set ON-time
6
2
of charge depends on the constant number. And so,
2
, arises in turning on. Take care in selecting the
33 μ s or more = 3.3%
Available Duty Ratio
(3.3% to 96.7%)
33 μ s or more = 3.3%
TB62737FPG
2010-11-16
1
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