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| NCL30105 Datasheet, PDF (3/22 Pages) ON Semiconductor – Constant Off Time PWM Current-Mode Controller | |||
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NCL30105
VCC
Vcc
Vtoff(open)
toff
VDIM(open)
DIM
RDIM
OVRI
UVLO
Von = VCC(on)
ok = 1, else 0
NC
Voff = VCC(off)
ref
1 = reset
1 = reset
tstart(delay)
set current
high
= rst
Q
toff
generator
SET
start
pulse
R
S
QQ
Q
SET
VSSTART(open)
ISSTART
SSTART
/ Iratio
S
Q
Q
R
GND
â
VILIM(fault)
VILIM
tLEB(fault)
tLEB
CS
ton >
ton(MAX)
Vcc
OVRI
down Nfault
up
count to Nfault
DRV
Figure 2. Internal Circuit Architecture
Table 1. PIN FUNCTION DESCRIPTION
Pin
Number
Pin Name
Function
1
toff
Adjusts the Off Time
Duration
2
DIM
Dimming Input
3
VCC
Supplies the Controller
4
CS
Current Sense Input
5
DRV
Driver Output
6
GND
â
7
SSTART
Softâstart / Peak Current
Adjustment
8
NC
Nonâconnected Pin
Pin Description
A resistor to ground sets the off time duration.
This pin is used for PWM dimming or to enable/disable the controller.
An external auxiliary voltage connected to this pin supplies the controller.
This pin monitors the peak current. When the peak current reaches the
internal threshold, the DRV is turned off.
The output of the driver is connected to an external MOSFET gate.
The controller ground.
A capacitor connected to this pin sets the softâstart duration. The voltage
of this pin adjusts the peak current set point for analog dimming.
Nonâconnected pin
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