MIC2827 Datasheet, PDF (22/27 Pages) Micrel Semiconductor – Triple Output PMIC with HyperLight Load™ DCDC, two LDOs, and I2C Control

Micrel, Inc.
Functional Description
DVIN
The DVIN pin provides power to the source of the
internal switch P-channel MOSFET, I²C control and
voltage references for the MIC2827. The DVIN operating
voltage range is from 2.7V to 5.5V. In order for any
MIC2827 outputs to regulate, the appropriate input
voltage must be applied to the DVIN pin. Due to the
high switching speeds, a 4.7µF capacitor is
recommended as close as possible to the DVIN and
power ground (DGND) pin for bypassing. Please refer to
layout recommendations.
LDO1IN
LDO1IN provides power to the source of the LDO1 P-
channel MOSFET. The LDO1IN operating voltage range
is from 1.8V to V_DVIN. The recommended bypass
capacitor is 1µF.
LDO2IN
LDO2IN provides power to the source of the LDO2 P-
channel MOSFET. The LDO2IN operating voltage range
is from 1.8V to V_DVIN. The recommended bypass
capacitor is 1µF.
EN
The enable pin controls the ON and OFF state of all the
outputs of the MIC2827. The EN pin is transition
sensitive and not level sensitive. By toggling the enable
pin low-to-high, this activates the default startup
sequence of the part.
SW
The switching pin connects directly to one end of the
inductor and provides the switching current during
switching cycles. The other end of the inductor is
connected to the load, output capacitor, and the FB pin.
Due to the high speed switching on this pin, the switch
node should be routed away from sensitive nodes.
FB
The feedback pin provides the control path to control the
output. A recommended 4.7µF bypass capacitor should
be connected in shunt with the DC-DC output. It is good
practice to connect the output bypass capacitor to the
DGND and FB should be routed to the top of C_OUT.
MIC2827
LDO1OUT
The LDO1OUT pin provides the regulated output voltage
of LDO1. Power is provided by LDO1IN. LDO1OUT
voltage can be dynamically scaled through I²C control.
The recommended output capacitance is 1µF,
decoupled to AGND.
LDO2OUT
The LDO2OUT pin provides the regulated output voltage
of LDO2. Power is provided by LDO2IN. LDO2OUT
voltage can be dynamically scaled through I²C control.
The recommended output capacitance is 1µF,
decoupled to AGND.
SCL
The I²C clock input pin provides a reference clock for
clocking in the data signal. This is a fast-mode 400kHz
input pin, and requires a 4.7kΩ pull-up resistor. Please
refer to “Serial Port Operation” for more details.
SDA
The I²C data bidirectional pin allows for data to be
written to and read from the MIC2827. This is a fast-
mode 400kHz I²C pin, and requires a 4.7kΩ pull-up
resistor. Please refer to “Serial Port Operation” for more
details.
IRQb
The IRQb (open drain) pin provides an interrupt for when
either the UVLO or TSD faults are asserted. When
enabled through I²C, the IRQb pin will assert together
with the corresponding fault condition. Please refer to
the “Interrupt Operation” for more details.
DGND
Power ground (DGND) is the ground path for the DC-DC
MOSFET drive current. The current loop for the Power
ground should be as small as possible and separate
from the Analog ground (AGND) loop. Refer to the layout
consideration for more details.
AGND
Analog ground (AGND) is the ground path for the biasing
and control circuitry. The current loop for the Analog
ground should be separate from the Power ground
(AGND) loop. Refer to the layout consideration for more
details.
July 2009
22
M9999-072709-A