MAX17061AEVKIT+ Maxim Integrated Products, MAX17061AEVKIT+ Datasheet - Page 11

• Manufacturer Part Number: MAX17061AEVKIT+
• Description: Power Management Modules & Development Tools MAX17061A EVAL KIT MAX17061A EVAL KIT
• Manufacturer: Maxim Integrated Products

Specifications of MAX17061AEVKIT+

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The MAX17061A is a high-efficiency driver for arrays of
white LEDs. It contains a fixed-frequency current- mode
PWM step-up controller, dimming control circuit, SMBus
interface, internal power MOSFET, and eight regulated
current sources (see Figure 2). When enabled, the step-
up controller boosts the output voltage to provide suffi-
cient headroom for the current sources to regulate their
respective string currents. The MAX17061A features
selectable switching frequency (500kHz, 750kHz, or
1MHz), which allows trade-offs between external com-
ponent size and operating efficiency.
WLED brightness is controlled by turning the WLEDs
on and off with a DPWM signal. The DPWM frequency
can be accurately adjusted with a resistor. The bright-
ness of the LEDs is proportional to the duty cycle of the
DPWM signal, which is controlled externally through
either a PWM or 2-wire SMBus-compatible interface, or
both. When both interfaces are used at the same time,
the product of the PWM duty cycle and SMBus com-
mand value is used for the dimming control. This
DPWM control scheme provides a full dimming range
with 8-bit resolution.
PIN
22
23
24
25
26
27
28
—
NAME
CCV
ISET
V
V
FB1
FB2
OV
EP
DD
CC
______________________________________________________________________________________
Boost Regulator MOSFET Gate Drive Supply. Bypass V
5V Control Supply Input. V
capacitor of 1μF or greater.
Step-Up Converter Compensation Pin. Connect a 0.022μF ceramic capacitor and 5.1k
to GND. When the MAX17061A shuts down, CCV is discharged to 0V through an internal 20k
Overvoltage Sense. Connect OV to the center tap of a resistive voltage-divider from V
detection threshold for voltage limiting at OV is 1.236V (typ).
Full-Scale LED Current Adjustment Pin. The resistance from ISET to GND controls the full-scale current in
each LED string:
The acceptable resistance range is 133k
of 30mA > I
LED String 1 Cathode Connection. FB1 is the open-drain output of an internal regulator, which controls
current through FB1. FB1 can sink up to 30mA. If unused, connect FB1 to V
LED String 2 Cathode Connection. FB2 is the open-drain output of an internal regulator, which controls
current through FB2. FB2 can sink up to 30mA. If unused, connect FB2 to V
Exposed Backside Pad. Solder to the circuit board ground plane with sufficient copper connection to
ensure low thermal resistance. See the PCB Layout Guidelines section.
Detailed Description
LEDMAX
SMBus for LCD Panel Applications
> 15mA. Connect ISET to V
8-String White LED Driver with
CC
provides power to the MAX17061A. Bypass V
I
LEDMAX
< R
The MAX17061A has multiple features to protect the
controller from fault conditions. Separate feedback
loops limit the output voltage in all circumstances. The
MAX17061A checks each FB_ voltage during the opera-
tion. If one or more strings are open, the corresponding
FB_ voltages are pulled below 175mV (typ), and open-
circuit fault is detected. As a result, the respective cur-
rent sources are disabled. When one or more LEDs are
shorted and the FB_ voltage exceeds 1.1 x V
fault is detected and the respective current source is
disabled. In either LED open or short conditions, the
fault strings are disabled while other strings can still
operate normally. The controller features cycle-by-
cycle current limit to provide stable operation and soft-
start protection. In a current-limit condition, the
controller shuts down after a 128µs overcurrent fault
timer expires. A thermal-shutdown circuit provides
another level of protection.
The MAX17061A requires an external 5V supply to pro-
vide the internal bias and gate drive for the step-up
controller.
= 20mA x 200k /R
ISET
CC
FUNCTION
for a default full-scale LED current of 25mA.
< 266k , which corresponds to full-scale LED current
DD
to GND with a ceramic capacitor of 1μF or greater.
Pin Description (continued)
ISET
CC
CC
CC
to GND with a ceramic
.
.
OUT
resistor from CCV
to ground. The
resistor.
CC
, short
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