Rainbow Electronics MAX17127 - Manual (Page 9)

_______________________________________________________________________________________ 9
MAX17127
Six-String WLED Driver with Integrated
Step-Up Converter
Pin Description
Pin Configuration
19
20
18
17
7
6
8
EN
FPO
9
V
DDIO
OVP FB1 FB2 PGND
1 2
COMP
4 5
15 14 12 11
V IN
PWM
+ EP
AGND
FB4
FB5
FB6
FSLCT
R_FPWM
3
13
I.C.
16 10 FB3 SW
THIN QFN
(4mm × 4mm)
TOP VIEW
ISET
MAX17127
PIN NAME FUNCTION
1 V DDIO
5V Linear Regulator Output. V DDIO provides power to the MAX17127. Bypass V DDIO to AGND with
a ceramic capacitor of 1FF or greater.
2 EN
Enable Pin. EN = high enables the MAX17127. An internal 200kI (typ) pulldown resistor keeps the
MAX17127 in disabled mode if the EN pin is high impedance.
3 FSLCT
Oscillator Frequency-Adjustment Pin. The resistance from FSLCT to AGND sets the step-up
converter’s oscillator frequency:
f SW = 1MHz O 100kI/R FSLCT
The acceptable resistance range is 100kI < R FSLCT < 400kI, which corresponds to the switching
frequency of 1MHz > f SW > 250kHz.
4 ISET
Full-Scale LED Current-Adjustment Pin. The resistance from ISET to AGND controls the full-scale
current in each LED string:
I LEDMAX = 20mA O 180kI/R ISET
The acceptable resistance range is 120kI < R ISET < 360kI, which corresponds to a full-scale LED
current of 30mA > I LEDMAX > 10mA. Connecting ISET to AGND sets the test mode for 0.3mA (typ)
full-scale LED current.
5 FPO
Fault-Diagnostic Output. Open drain, active low. The FPO output is asserted low when the following
faults occur: overcurrent fault, thermal fault, output-voltage short condition, or output overvoltage.
6 FB6
LED String 6 Cathode Connection. FB6 is the open-drain output of an internal regulator, which
controls current through FB6. FB6 can sink up to 30mA. If unused, connect FB6 to AGND.