MIC2860-2PYD6 TR Micrel Inc, MIC2860-2PYD6 TR Datasheet - Page 8

• Manufacturer Part Number: MIC2860-2PYD6 TR
• Description: IC WHITE LED DRIVER PWM SOT-23-6
• Manufacturer: Micrel Inc
• Series: -r

Specifications of MIC2860-2PYD6 TR

• Constant Current: -
• Constant Voltage: -
• Topology: Linear (LDO)
• Number Of Outputs: 2
• Internal Driver: Yes
• Type - Primary: Backlight
• Type - Secondary: White LED
• Frequency: -
• Voltage - Supply: 3 V ~ 5.5 V
• Voltage - Output: 0 V ~ 5.5 V
• Mounting Type: Surface Mount
• Package / Case: SOT-23-6
• Operating Temperature: -40°C ~ 85°C
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 576-3940-2

Functional Description
The MIC2860-2P is a two channel WLED driver. The
WLED driver is designed to maintain proper current
regulation with LED current accuracy of 1% with a typical
matching between the 2 channels of ±0.5%. The WLEDs
are driven independently from the input supply and will
maintain regulation with a dropout of 52mV at 30.2mA.
The low dropout of the linear drivers allows the WLEDs
to be driven directly from the battery voltage and
eliminates the need for large and inefficient charge
pumps. The peak WLED current for each channel is set
via an external resistor. If dimming is desired the
MIC2860-2P can dim via a PWM signal.
Block Diagram
As shown in Figure 1, the MIC2860-2P consists of two
current sinks with the peak current determined by R
The linear drivers have a designated control block for
enabling and dimming of the WLEDs. The MIC2860-2P
is controlled by the PWM control block that receives
PWM signals for dimming.
VIN
The input supply (V
drivers and the control circuitry. The V
is 3V to 5.5V. Due to wire inductance a minimum bypass
capacitor of 1µF should be placed close to input (VIN)
pin and the ground (GND) pin.
EN
The EN pin enables the linear drivers. It can also be
used for dimming with a PWM signal. See the PWM
Dimming Interface in the Application Information section
for details. Do not leave floating.
R
The R
ground to set the peak current of the linear drivers. The
maximum LED current (EN = 100% Duty Cycle) set by
the R
A plot of I
Micrel Inc.
Table 1. Maximum LED Current vs. R
September 2010
SET
SET
SET
resistor is shown in the table below:
R
LED
SET
pin is used by connecting a R
9.53
11.5
14.3
15.8
19.1
28.7
versus R
(kΩ)
IN
SET
) provides power to the linear
is shown in Figure 2.
SET
I
IN
LED
Resistor Values
operating range
30.2
25.0
20.1
18.2
15.1
10.0
SET
(mA)
resistor to
SET
.
8
D1, D2
The D1 and D2 pins are the linear driver inputs for
WLED 1 and 2, respectively. Connect the anodes of the
WLEDs to V
and D2. When operating with a single WLED, D1 and D2
should be connected to the WLED cathode to parallel
the
Paralleling these pins can also be done to drive a higher
current through a single WLED. Do not leave these pins
floating.
GND
The ground pin is the ground path for the linear drivers.
The current loop for the ground should be as small as
possible. The ground of the input capacitor should be
routed with low impedance traces to the GND pin and
made as short as possible.
outputs
Figure 2. Peak LED Current vs. R
IN
35
30
25
20
15
10
5
0
and each cathode of the WLEDs to D1
8
for
12
improved
Peak LED Current
16
vs. R
R
SET
20
(kΩ)
SET
dropout
24
M9999-092710-A
28
MIC2860-2P
SET
performance.
32