mic3289 Micrel Semiconductor, mic3289 Datasheet - Page 9

• Manufacturer Part Number: mic3289
• Description: Mic3289 1.2mhz Pwm White Led Driver With Internal Schottky Diode And True 1-wire Digital Control
• Manufacturer: Micrel Semiconductor

With an input supply voltage between 2.5V and 6.5V and
a logic-level LOW applied to the DC pin, the MIC3289
will enter State 0, shutdown, and remain there
consuming less than 1µA.
Start Up
Presuming no presetting brightness command is issued
(discussed in a later section), the MIC3289 will start-up
in its default state approximately 140µs (t
logic level high has been applied and maintained at the
DC pin. In the default state the LED drive current is at
the maximum brightness level of 15 and brightness
counter is set to count down mode. Any falling edges
during the t
brightness level of the LEDs to be below the maximum
brightness level. This is discussed in more detail in the
Presetting Brightness section.
Shutdown
Whenever a logic-level LOW is applied to the DC input
pin
t
entering its power saving shutdown mode.
SHUTDOWN
Micrel, Inc.
June 2007
for
(1260µs), the MIC3289 will return to State 0
a
Figure 2. Typical Start-Up Timing
PROG_SETUP
period
greater
period will cause the initial
than
START_UP
or
Figure 1. MIC3289 Logic State Diagram
equal
) after a
to
9
Once the device is shutdown, the boost supply is
disabled and the LEDs are turned off. Brightness level
information stored in the MIC3289 prior to shutdown will
be lost.
Programming Pulse Counter Modes
Referring to the state diagram in Figure 1, notice that
there are two programming pulse counting modes. At
power up the MIC3289 defaults to State 1, the Count
Down Mode. The counting mode can be changed to
State 2, the Count Up Mode, by pulling the DC pin low
for a period equal to t
device will remain in Count Up Mode until its state is
changed to Count Down Mode or by disabling the
MIC3289.
Figure 4. Mode Change to Count Up
Figure 3. Shutdown Timing
MODE_UP
(100µs to 160µs). The
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M9999-061807
MIC3289