ELM901FxA 1A 2x Charge Pump LED Driver
EN1 : on/off control 1
LED output current on/off control pin of set current of ISET1. This pin is pulled down to ground inside
the IC and the control logic is high active. The set current of ISET1 sinks from LED pin when this pin is
connected to VIN.
AGND : internal analog circuit ground
This pin should be connected to GND of internal analog circuit and is connected in short circuit with internal
circuit on back pad. The connection to PGND1 & PGND2 is required and should be designed according to
the external wiring.
FS : fail safe setting
When EN1=EN2=1 continues for a period of time, fail safe function will turn down LED current forcibly.
This function aims for thermal protection of LED, and it is possible to be turned off. There are 3 timer
options according to the resistor connected between FS and GND since EN1=EN2=1 until LED current is
off: (1)1s when the resistor is short, (2)0.2s when the resistor is 20kΩ, and (3)0.5s when the resistor is 51kΩ.
This fail safe function becomes ineffective when it is short between FS and VIN or FS is open.
VIN : internal circuit power
This pin should be connected to the power pin of internal circuit. The connection to PVIN is required and
should be designed according to the external wiring; GND-connected ceramic capacitor( above 2.2μF) is
also necessary.
PGND1 : charge pump circuit ground
This pin should be connected to GND of charge pump circuit. The connection to AGND & PGND2 is
required and should be designed according to the external wiring.
CM : step-up capacitor connection( low potential)
This pin should be connected to the low potential of step-up capacitor. The wiring of step-up capacitor
should be connected between CM and CP as closely as possible; ELM recommends using 2.2μF capacitor.
PVIN : charge pump power
This pin is power supply of charge pump circuit. This pin should be connected to VIN according to the
external wiring.
CP : step-up capacitor connection( high potential)
This pin should be connected to the high potential of step-up capacitor. The wiring of step-up capacitor
should be connected between CM and CP as close as possible; ELM recommends using 2.2μF capacitor.
VO : step-up output
The output voltage is almost the same as VIN under 1x mode, while it becomes 5.5V under step-up mode.
This pin should be connected to LED anode.
PGND2 : LED current drive circuit ground
This pin should be connected to the GND of LED current drive circuit. The connection to AGND & PGND1
is required and should be designed according to the external wiring.
LED : constant current sink
To sink the output current which is set by ISET1 & ISET2. This pin should be connected to LED cathode.
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