nud4330 ON Semiconductor, nud4330 Datasheet - Page 8

• Manufacturer Part Number: nud4330
• Description: Three Channel Linear Led Driver
• Manufacturer: ON Semiconductor

Where:
T
C
Thermal Shutdown
junction and removes the gate drive of all FETs if the
maximum level (150°C) is exceeded. There is a nominal
hysteresis of 10°C for this circuit. After a thermal shutdown,
the device will automatically restart when the temperature
drops to a safe level as determined by the hysteresis.
Minimum Vdrop
the drain-to-source terminals of each of the FETs and R
for operation. Since V
V
according the following formula:
drain-to-source terminals of each of the FETs and its
respective Rsense for regulation.
Maximum Vdrop
be limited by the device's max power dissipation. That is, the
voltage drop across each of the internal FETs should be
taken into account for the calculation of the device's total
delay
delay
drop
The temperature limit circuit senses the temperature of the
There is a minimum voltage drop required to have across
This will be the minimum voltage required across the
The maximum voltage drop in each of the channels will
= Wanted delay time (seconds)
= Delay capacitor (Farads)
required will change for different I
Vdrop
min
+ I
LED
drop
= V
R
DS(on)
DS
+ V
) 0.5 V
Rsense
, the minimum
LED
currents
http://onsemi.com
(eq. 3)
NUD4330MN
sense
8
power dissipation. The following formula is used to
calculate the device's total power dissipation:
Where V
The resulting total power dissipation should not exceed the
PD value shown on the maximum ratings table.
Power Dissipation
dissipation considerations should be taken into account.
That is, the device's power dissipation listed on the
maximum ratings table is for T
power dissipation capability will be derated for higher
temperatures than 25°C. The following formula may be used
for those purposes:
Enable Circuit
channels or for PWM dimming purposes. The PWM
frequency is recommended to be between 100 Hz and
1 kHz. Each of the enable circuits have an internal 0.6 MW
pullup resistor connected to an internal 9 V voltage source.
So if left open, the channel will automatically be enabled.
P
P
Since the NUD4330 device is a linear device, power
The enable circuit can be used to enable/disable the
Dtotal
Dtotal
T
+ P
+ V
J
DS(n)
) V
+ T
Dcontrol
CC
DS2
= V
A
) R
* 2.5 mA ) V
* I
DD(n)
) P
LED2
qJA
Dch1
- V
) V
P
LEDs(n)
) P
D
DS3
DS1
A
Dch2
= 25°C. So the device's
* I
* I
- 0.5V
LED3
) P
LED1
Dch3
(eq. 4)
(eq. 5)
(eq. 6)