STLDC08 STMicroelectronics, STLDC08 Datasheet - Page 14

• Manufacturer Part Number: STLDC08
• Description: Step-up controller for LED supply
• Manufacturer: STMicroelectronics

Detailed description
Figure 17. Timing diagram
7.3
7.4
14/29
PWMOUT
PWMOUT
V
V
2VCC
2VCC
OUT
OUT
V
V
DRV
DRV
1.9 V
1.9 V
ILED
ILED
CC
CC
I
I
1.7 V
1.7 V
CC
CC
Over voltage protection (OVP)
As with any current source, the output voltage rises when the output gets high impedance or
is disconnected. To prevent the output voltage exceeding the maximum switch voltage rating
of the main switch, an overvoltage protection circuit is integrated. As soon as the output
voltage exceeds the OVP threshold, the converter stops switching and the output voltage
drops. When the output voltage falls below the OVP threshold, the converter continues
operation until the output voltage exceeds the OVP threshold again.
Enable/PWM
The enable pin allows disabling and enabling of the device as well as brightness control of
the LEDs by applying a PWM signal. In order to avoid visible flicker, the frequency of the
PWM signal should be higher than 120 Hz. Changing the PWM duty cycle therefore
changes the LED brightness.
Charge Pump
Charge Pump
active
active
Follows EN/PWM
Follows EN/PWM
input
input
STLDC08 supplied by
STLDC08 supplied by
Doc ID 18476 Rev 1
V
V
OUT
OUT
V
V
supplied by V
supplied by V
OUT
OUT
>1.9 V STLDC08 is
>1.9 V STLDC08 is
OUT
OUT
V
V
flowing through the LEDs
flowing through the LEDs
OUT
OUT
PWMOUT is realeased
PWMOUT is realeased
Soft start cycle ended,
Soft start cycle ended,
> V
> V
LED
LED
, the current starts
, the current starts
AM07847v1
AM07847v1
STLDC08