MAX17061ETI+ Maxim Integrated Products, MAX17061ETI+ Datasheet - Page 11

• Manufacturer Part Number: MAX17061ETI+
• Description: IC LED DRVR WHITE BCKLGT 28-TQFN
• Manufacturer: Maxim Integrated Products
• Type: Backlight, White LEDr

Specifications of MAX17061ETI+

• Topology: PWM, Step-Up (Boost)
• Number Of Outputs: 8
• Internal Driver: Yes
• Type - Primary: Automotive, Backlight
• Type - Secondary: White LED
• Frequency: 1MHz
• Voltage - Supply: 4.5 V ~ 26 V
• Voltage - Output: 5V
• Mounting Type: Surface Mount
• Package / Case: 28-TQFN Exposed Pad
• Operating Temperature: -40°C ~ 85°C
• Current - Output / Channel: 30mA
• Internal Switch(s): Yes
• Operating Supply Voltage: 5 V
• Maximum Supply Current: 2 mA
• Maximum Power Dissipation: 1667 mW
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Efficiency: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

The MAX17061 is a high-efficiency driver for arrays of
white LEDs. It contains a fixed-frequency current-
mode PWM step-up controller, a 5V linear regulator,
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 sufficient head-
room for the current sources to regulate their respec-
tive string currents. The MAX17061 features selectable
switching frequency (500kHz, 750kHz, or 1MHz), which
allows trade-offs between external component size and
operating efficiency. The control architecture automati-
cally skips pulses at light loads to improve efficiency
and prevents overcharging the output capacitor.
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
PIN
22
23
24
25
26
27
28
—
NAME
CCV
ISET
V
V
FB1
FB2
OV
EP
DD
CC
______________________________________________________________________________________
Boost Reg ul ator M OS FE T G ate D r i ve S up p l y. Byp ass V
5V Linear Regulator Output. V
capacitor of 1µF or greater. If V
external 5V supply to V
Step-Up Converter Compensation Pin. Connect a 0.022µF ceramic capacitor and 5.1k
GND. When the MAX17061 shuts down, CCV is discharged to 0V through an internal 20k resistor.
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 < R
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
CC
8-String White LED Driver with
.
CC
IN
provides power to the MAX17061. Bypass V
is less than or equal to 5.5V, tie V
I
LEDMAX
CC
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.
The MAX17061 has multiple features to protect the con-
troller from fault conditions. Separate feedback loops limit
the output voltage in all circumstances. The MAX17061
checks each FB_ voltage during the operation. 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 current sources are
disabled. When one or more LEDs are shorted and the
FB_ voltage exceeds 1.1 x V
and the respective current source is disabled. In either
LED open or short conditions, the fault strings are dis-
abled 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 cir-
cuit provides another level of protection.
ISET
= 20mA x 200k /R
for a default full-scale LED current of 25mA.
FUNCTION
< 266k , which corresponds to full-scale LED current of
D D
to G N D w i th a cer am i c cap aci tor of 1µF or g r eater .
Pin Description (continued)
ISET
CC
to IN to disable internal LDO and use
CC
CC
CC
.
.
CC
to GND with a ceramic
, short fault is detected
OUT
resistor from CCV to
to ground. The
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