Datasheet

13
MSL2021 [DATASHEET]
42062A–LED–02/2013
NC 7, 17 No Internal Connection
THM 8
NTC Thermistor Sensing Input
Connect a negative temperature coefficient thermistor (ERT-J0EG103FA or equivalent) from THM to
AGND, in series with a 1.5k resistor. Locate the thermistor close to the Color-Adjust LEDs to monitor
their temperature. This allows the MSL2021 to automatically temperature compensate the Color-
Adjust string brightness.
REXT 9
External Resistor
Connect a 46.4k, 1% resistor from REXT to AGND.
TOFF 10
Off-Time Set Input
A resistor from TOFF to AGND controls the constant off time for the Color-Adjust string floating buck
converter, where R
TOFF
= t
OFF
 (90.9 x 10
9
), with t
OFF
in seconds and R
TOFF
in Ohms. For example, an
off time of 0.5s results in a resistor value of 45.3k (to the nearest 1% value).
DNC 11
Do Not Connect
Do not make external connection to DNC.
CGND 12
Connect to Ground
Connect CGND to AGND.
CS 13
Current Sense Input for the Color-Adjust String
Connect CS to the external current sense resistor of the Color-Adjust string. The current sense
threshold is 200mV.
PGND 14
Power Ground
PGND is the ground connection for the FET gate drivers. Connect PGND to AGND close to the
MSL2021.
DRV 15
Gate Drive for Color-Adjust (Floating Buck Regulator) MOSFET
Connect DRV to the gate of the external power MOSFET.
PVIN 16
Power Voltage Input
PVIN powers DRV, the floating buck FET gate driver. Bypass PVIN to PGND with a 1.0µF or greater
capacitor.
S 18
Source Sense Input for Main LED String MOSFET
Connect S to the source of the external MOSFET, and to the current sense resistor for the Main LED
string. The current sense threshold is 200mV.
G 19
Gate Output for Main String MOSFET
Connect G to the gate of the Main string external MOSFET.
D 20
Drain Output for Main String MOSFET
Connect D to the drain of the Main string external MOSFET.
AVIN 21
Analog Voltage Input
AVIN is the power input to the MSL2021. Bypass AVIN to AGND with a 1.0µF or greater capacitor
placed close to AVIN.
VCC 22
5V Internal Voltage
Connect 10uF bypass capacitor from VCC to AGND.
AGND 23
Analog Ground
Connect AGND to system ground.
VDD 24
2.5V Internal Voltage
Connect 10uF bypass capacitor from VDD to AGND.
EP EP
Exposed Pad
EP is the Main thermal path for heat to escape the die. Connect EP to a large copper plane connected
to PGND and AGND.
Name Pin Description