CAT3643
RECOMMENDED EN/DIM TIMING
For 2.4V ≤ VIN ≤ 5.5V, over full ambient temperature range -40ºC to +85ºC.
Symbol Name
TSETUP EN/DIM setup from shutdown
TLO
Conditions
Min
10
Typ
Max
Units
μs
EN/DIM program low time
EN/DIM program high time
0.2
0.2
1.5
100
μs
THI
μs
TPWRDWN EN/DIM low time to shutdown
ms
μs
TLED
LED current settling time
40
T
T
T
HI
PWRDWN
SETUP
EN/DIM
T
LED
T
LO
100%
100%
50%
25%
12.5%
LED
Current
6.25%
3.12%
Shutdown
Shutdown
Figure 1. EN/DIM Digital Dimming Timing Diagram
LED Current Setting
The nominal LED current is set by the external
resistor connected between the RSET pin and
ground. Table 1 lists standard resistor values for
several LED current settings.
LED Current (mA)
RSET (kΩ)
40.0
2
5
15.8
10
15
20
25
30
7.87
5.23
4.02
3.16
2.67
Table 1. Resistor RSET and LED Current
Doc. No. MD-5022 Rev. E
4
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
CATALYST [ CATALYST SEMICONDUCTOR ]
