SGM3122 Datasheet, PDF (10/17 Pages) SG Micro Corp – PWM Brightness Control

SGM3122
White LED Charge Pump Current
Source with PWM Brightness Control
DETAILED DESCRIPTION
Table 1. Enable Levels
ENABLE LEVEL
EN2
EN1
0
0
0
1
1
0
1
1
VISET
0
200 mV
400 mV
600 mV
LED CURRENT
0
1/3
2/3
Full
Table 2. R_ISET Values
SET DRIVE
CURRENT
(Full)
R_ISET COMPUTATION
VALUE (kΩ)
30mA
5.1
25mA
6.12
20mA
7.65
10mA
15.3
5mA
30.6
STANDARD
RESISTOR
VALUE (kΩ)
5.1
6.19
7.68
15.4
30.9
Short-Circuit and Over-Temperature Protection
The current at the VOUT pin is limited typically to 300mA.
When the junction temperature exceeds 160°C, the
device shuts down to protect the device from damage.
After the temperature decreases to about 140°C, the
device starts up again if it is enabled.
Over-Voltage Protection at VOUT
The device uses the voltage at D1 to regulate voltage at
VOUT. In case D1 is not connected, an overvoltage
protection circuit ensures that the output voltage at VOUT
does not exceed its limits. The connection of the LEDs
must be started using D1 first. For all other LEDs there is
no restriction in the sequence. For example, if there are
only 2 LEDs used, the first LED is connected to D1 and
the other LED can be connected to any other of the D2 to
D4 pins.
Under-Voltage Lockout
The under-voltage lockout circuit shuts down the device
when the voltage at VIN drops below a typical threshold
of 2.15V. This prevents damage to the device. The UVLO
circuit allows the device to start up again after the voltage
on the VIN pin has increased by about 50mV above the
UVLO lockout threshold.
SG Micro Corp
10
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