DA6251.002
27 October, 2017
Note that use of external VOUT adjusting feedback resistors increases shutdown current by amount of IEXT_FB
=
VIN/(R1+R2) since VOUT follows VIN voltage when the device is in shutdown. To keep the shutdown current low
the external feedback resistance (R1+R2) path should be kept near 10M level. For good feedback regulation the
max R1 should not exceed 400k.
When driving LEDs they are connected in series from VOUT to ILED which is the current sink pin. Additionally LED
current setting resistor RLED needs to be connected from RLED pin to GND. See figures 4-6. The table 4 shows
example RLED resistor values and corresponding LED current levels. Additionally PWM signal can be applied to
the CTRL pin for LED dimming to reduce average LED current from level defined with the RLED resistor.
Table 4. LED current setting resistor examples
RLED
[Ω]
ILED
[mA]
40.2
20
5.0
10.0
15.0
13.3
Note: ILED=VRLED/RLED, VRLED=0.2V typ
11 (21)
MAS [ MICRO ANALOG SYSTEMS ]
