MAX1916EZT+T Maxim Integrated Products, MAX1916EZT+T Datasheet - Page 6

• Manufacturer Part Number: MAX1916EZT+T
• Description: IC LED DRIVER LINEAR TSOT-6
• Manufacturer: Maxim Integrated Products
• Type: Linear (Non-Switching)r

Specifications of MAX1916EZT+T

• Constant Current: Yes
• Topology: Linear (LDO)
• Number Of Outputs: 3
• Internal Driver: Yes
• Type - Primary: Backlight
• Type - Secondary: White LED
• Voltage - Supply: 2.5 V ~ 5.5 V
• Mounting Type: Surface Mount
• Package / Case: TSOT-23-6, TSOT-6
• Operating Temperature: -40°C ~ 85°C
• Current - Output / Channel: 60mA
• Internal Switch(s): Yes
• Number Of Segments: 3
• Low Level Output Current: 60 mA
• Operating Supply Voltage: 2.5 V to 5.5 V
• Maximum Power Dissipation: 727 mW
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Output: -
• Frequency: -
• Efficiency: -
• Lead Free Status / Rohs Status: Details

Low-Dropout, Constant-Current
Triple White LED Bias Supply
Figure 2. Very Low-Cost, High-Efficiency Solution
Figure 3. Brightness Adjust Using DAC
Figure 4. Existing 5V Supply Circuit
6
_______________________________________________________________________________________
REGULATOR
EXISTING
V
ON
ON
DAC
BATT
EXISTING
ON
LDO
V+
OFF
OFF
OFF
5.0V
V
V
CTRL
CTRL
EN
EN
SET
EN
SET
SET
MAX1916
MAX1916
MAX1916
LED1 LED2 LED3
LED1 LED2 LED3
LED1 LED2 LED3
V+
GND
GND
GND
V+
TO OTHER
CIRCUITS
TO OTHER
CIRCUITS
SET controls the LED bias current. Current flowing into
LED1, LED2, and LED3 is 230 times greater than the
current flowing into SET. Set the output current as fol-
lows:
where V
between 1.8V and 5.5V, and R
nected between V
1) Very Low-Cost, High-Efficiency Solution (Figure 2).
2) Brightness Adjustment Using a DAC (Figure 3). A
3) Existing 5V Supply (Figure 4). Use an existing sys-
TRANSISTOR COUNT: 220
PROCESS: BiCMOS
A battery (single Li+ or three NiMH cells) powers
the LEDs directly. This is the least expensive and
most efficient architecture. Due to the high forward
voltage of white LEDs (3.3V), the LED brightness
may dim slightly at the end of battery life. The
MAX1916’s current-regulating architecture and low
dropout greatly minimize this effect compared to
using simple ballast resistors. The enable function
of the MAX1916 turns on and off the LEDs. An exist-
ing low-dropout regulator is used as V
DAC is used as V
may be dynamically adjusted to eliminate factory
calibration. A battery (single Li+ or three NiMH
cells) or a regulated power source drives the LEDs.
tem regulator, such as the MAX684, to provide the
required LED voltage and provide power to other
circuits. Due to the high forward voltage of white
LEDs (3.3V), use a 3.6V to 5.5V regulated supply to
provide enough voltage headroom such that the
LEDs will maintain constant brightness for any bat-
tery voltage. Use the existing regulated supply as
V
CTRL
SET
.
= 1.215V, V
I
LED
Applications Information
CTRL
_
=
Setting the Output Current
CTRL
230
and SET
CTRL
(
such that the LED brightness
V
CTRL
Chip Information
R
SET
is an external voltage
SET
(Figure 1).
−
V
is the resistor con-
SET
)
CTRL
.