MAX17061A Maxim Integrated Products, MAX17061A Datasheet - Page 12

• Manufacturer Part Number: MAX17061A
• Description: 8-String White LED Driver
• Manufacturer: Maxim Integrated Products

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8-String White LED Driver with
SMBus for LCD Panel Applications
The MAX17061A’s fixed-frequency, current-mode,
step-up controller automatically chooses the lowest
active FB_ voltage to regulate the output voltage.
Specifically, the difference between the lowest FB_ volt-
age and the current-source control signal plus an offset
(VSAT) is integrated at the CCV output. The resulting
error signal is compared to the external switch current
plus slope compensation to determine the switch on-
time. As the load changes, the error amplifier sources
or sinks current to the CCV output to deliver the
required peak-inductor current. The slope-compensa-
tion signal is added to the current-sense signal to
improve stability at high duty cycles.
Figure 1. Typical Operating Circuit
12
______________________________________________________________________________________
Fixed-Frequency Step-Up Controller
464k
PWM
DATA
CLK
+5V
V
CC
1 F
1 F
7V TO 21V
V
IN
0.022 F
5.1k
4.7 F
220pF
0.1 F
V
OSC
ISET
FSET
CCV
PWMI
PWMO
SCL
SDA
GND
V
CC
DD
MAX17061A
EP
IN
10 H
L1
PGND1
PGND2
LX1
LX2
FB2
FB3
FB4
FB5
FB6
FB7
FB8
FB1
OV
At high input voltages when the on-time is pushed to be
lower than the minimum on-time (90ns typ), the boost
converter runs with minimum on-time, boosting the out-
put voltage higher than the input voltage.
The MAX17061A requires an external 5V VCC supply
for internal control voltage.
The MAX17061A includes power-on reset (POR) and
undervoltage lockout (UVLO) features. POR resets the
fault latch and sets all the SMBus registers to their POR
values. POR occurs when V
The controller is disabled until V
threshold of 4.25V (typ). Hysteresis on UVLO is approx-
imately 85mV.
The V
with a minimum 1µF ceramic capacitor.
R2
61.9k
C
D1
2 F
OUT
2.21M
CC
V
CC
R1
and V
DD
pins should be bypassed to GND
5V Supply V
UP TO 45V
V
CC
OUT
rises above 2.8V (typ).
CC
exceeds the UVLO
CC
and UVLO