MAX1986ETE+T Maxim Integrated Products, MAX1986ETE+T Datasheet - Page 13

• Manufacturer Part Number: MAX1986ETE+T
• Description: IC LED DRVR WHITE BCKLGT 16-TQFN
• Manufacturer: Maxim Integrated Products
• Type: Backlight, White LEDr

Specifications of MAX1986ETE+T

• Topology: PWM, Step-Up (Boost)
• Number Of Outputs: 4
• Internal Driver: Yes
• Type - Primary: Backlight
• Type - Secondary: White LED
• Frequency: 800kHz ~ 1.2MHz
• Voltage - Supply: 2.7 V ~ 5.5 V
• Mounting Type: Surface Mount
• Package / Case: 16-TQFN Exposed Pad
• Operating Temperature: -40°C ~ 85°C
• Current - Output / Channel: 25mA
• Internal Switch(s): Yes
• Efficiency: 90%
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Output: -
• Lead Free Status / Rohs Status: Details

capacitor can be connected from BITB to ground to
increase the total time constant. Use the following
equation to calculate the total time constant:
where C
The recommended DPWM duty-factor range is from
20% to 100% for DPWM frequencies between 20kHz
and 2MHz, using the internal 0.1ms filter. For lower
DPWM operating frequencies, use C
voltage on C
above DF
mum reliable DPWM duty factor of 15%.
In DPWM mode, the MAX1984/MAX1985/MAX1986
enter shutdown mode when the DPWM duty cycle is
below 5% (typ) and BITC is a logical low level.
To use the analog control mode, connect MODE, BITA,
and BITC to IN. Connect BITB to a DC voltage that sets
the LED current. The operational range for the analog
Figure 5. Brightness Control Equivalent Functional Diagram
EXT
MIN
is the external capacitance.
R
τ = 0.2MΩ
SETI
✕
EXT
MODE
BITA
BITB
BITC
SETI
0.75
______________________________________________________________________________________
(BITB), including ripple, remains
✕
V
✕
300kΩ
REF
C
0.75 x V
EXT
, where DF
LEVEL
SHIFT
+ 0.098ms
DECODER
REF
V
IN
EXT
200kΩ
- 0.7V
SETI
Analog Control
3-BIT
MIN
and ensure the
0.75 x V
18mA DEFAULT
is the mini-
9.8MΩ
DAC
REF
Ultra-High-Efficiency White
10pF
THRESHOLD
200kΩ
SHUTDOWN
0.045V
control is from 140mV (15%) to 0.75
The LED current is given by the following equation:
where K1 = 0.0465, K2 = 0.953, V
the BITB pin, V
and I
In analog mode, the MAX1984/MAX1985/MAX1986
enter shutdown mode when both V
logic low.
The MAX1984/MAX1985/MAX1986 also support 2-bit or
3-bit parallel control. To use the 3-bit parallel control
mode, connect MODE to ground. BITA is the most sig-
nificant bit and BITC is the least significant bit. To use
the 2-bit parallel control, connect MODE to IN and BITC
to ground. BITA is the most significant bit and BITB is
the least significant bit. In parallel mode, the
MAX1984/MAX1985/MAX1986 enter shutdown mode
when BITA, BITB, and BITC are logic low. Tables 3 and
4 are the truth tables.
SETI
LED(FS)
0.5mA TEST
I
LED
is the full-scale LED current set by SETI.
=
REF



K
1
1
7.2MΩ
is the 1.25V internal reference voltage,
+
K
V
IN
2
×
100
0 75
LED Drivers
.
38Ω
V
BITB
×
V
IREF
TO CURRENT
REGULATORS
REF
BITB
BITA
SHUTDOWN

 ×

Parallel Control
✕
is the voltage at
I
LED FS
and V
V
REF
(
)
BITB
(100%).
are
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