MAX1579 Maxim Integrated Products, MAX1579 Datasheet - Page 7

• Manufacturer Part Number: MAX1579
• Description: Complete Bias and White LED Power Supplies for Small TFT Displays
• Manufacturer: Maxim Integrated Products

Complete Bias and White LED Power Supplies
PIN
11
12
13
14
15
16
17
18
19
20
21
22
23
24
—
ONBIAS
NAME
COMP
PGND
CTRL
GND
OUT
C1N
C2N
C2P
C1P
V
CS
LX
EP
_______________________________________________________________________________________
IN
DD
Logic Input to Enable V
charge pumps. Connect to GND to disable the charge pumps.
Ground. Connect to PGND and the exposed pad directly under the IC.
LED Driver Compensation. Connect a 0.1µF from COMP to GND. C
sets the soft-start time.
Current-Sense Feedback Input. Connect a resistor from CS to GND to set the LED current. For the
MAX1578, CS regulates to V
V
LE D Br i g htness C ontr ol Inp ut. C onnect C TRL to a 0.24V to 1.65V i np ut to set the b r i g htness of the
exter nal LE D s. H ol d C TRL b el ow 100m V for m or e than 10.5m s, to shut d ow n the LE D d r i ver . D r i ve C TRL
w i th a 200H z to 200kH z unfi l ter ed P W M d i m m i ng si g nal for D C LE D cur r ent that i s p r op or ti onal to the
si g nal ’ s d uty cycl e.
Over vol tag e S ense Inp ut. The M AX 1578/M AX 1579 tur n off the n- channel M OS FE T w hen V
Once V
Inductor Connection. Connect to the switched side of the external inductor as well as the anode of the
external diode. LX is high impedance during shutdown.
Power Ground. Connect to GND and the exposed pad directly under the IC.
Main Charge-Pump Transfer Capacitor Negative Connection 1. Connect a 2.2µF capacitor between
C1N and C1P.
Main Charge-Pump Transfer Capacitor Negative Connection 2. Connect a 2.2µF capacitor between
C2N and C2P.
P ow er - S up p l y Inp ut. C onnect to a 2.7V to 5.5V i np ut sup p l y. Byp ass IN to GN D w i th a 4.7µF cap aci tor .
Main Charge-Pump Transfer Capacitor Positive Connection 2. Connect a 2.2µF capacitor between
C2P and C2N.
Main Charge-Pump Transfer Capacitor Positive Connection 1. Connect a 2.2µF capacitor between
C1P and C1N.
Regulated Main Charge-Pump Output. V
capacitor. V
Exposed Paddle. Connect directly to a ground plane, GND, and PGND directly under the IC.
CTRL
/ 5 or 0.340V, whichever is lower.
OU T
d r op s b el ow 32V , the IC r e- enter s soft- star t. Byp ass OU T to GN D w i th a 0.1µF cap aci tor .
DD
is connected to IN when ONBIAS is pulled low.
DD
, MAIN, POS, and NEG Charge Pumps. Drive ONBIAS high to enable all the
CTRL
/ 5 or 0.327V, whichever is lower. For the MAX1579, CS regulates to
for Small TFT Displays
DD
is regulated to 5.5V. Bypass V
FUNCTION
Pin Description (continued)
COMP
stabilizes the driver and
DD
to GND with a 4.7µF
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OU T
exceed s 34V .
7