MIC23099 Datasheet, PDF (3/26 Pages) Micrel Semiconductor – Single AA/AAA Cell Step-Up/Step-Down Regulators

Micrel, Inc.
MIC23099
Pin Description (Continued)
Pin
Number
7
8
9
10
11
12
13
14
EP
Pin Name Pin Function
LED
AGND
FB2
OUT2
PGND2
SW2
OUT1
SW1
GND
LED (Output): This is an open drain output that is used for a low battery indicator. Under normal
conditions, the LED is always ON. If the battery voltage is between 1.2V to 0.85V, the external LED will
blink with a duty cycle of 25% at 0.25Hz. The LED will be OFF if the battery voltage falls below 0.85V for
more than 15 cool-off cycles or the EN pin is low.
Analog Ground: The analog ground for both regulator control loops.
Feedback 2 (Input): Connect a resistor divider network to this pin to set the output voltage for the
synchronous buck regulator. Resistors should be selected based on a nominal VFB2 = 0.6V.
Output Voltage 2 (Input): If the EN is low or the power good output is pulled low, an internal resistor
discharges VOUT2 output capacitance to 0V. Also, if the inductor current falls to zero an internal anti-
ringing switch is connected between the SW2 and OUT2 pins to minimize the switch node ringing.
Power Ground 2: The power ground for the synchronous buck DC/DC converter power stage.
Switch Pin 2 (Input): Inductor connection for the synchronous step-down regulator. Connect the inductor
between VOUT2 and the SW2 pin. Due to the high-speed switching on this pin, the SW2 pin should be
routed away from sensitive nodes and trace length should be kept as short and wide as possible to
reduce EMI. If the inductor current falls to zero or EN is low, then an internal anti-ringing switch is
connected between the SW2 and VOUT2 pins to minimize the switch node ringing.
Output 1 (Output): Output of the synchronous boost regulator and is the bias supply once VOUT1 is
greater than VIN. The boost output also serves as the supply input for the buck converter (VOUT2). If the
EN is low or the power good output is pulled low, an internal resistor discharges VOUT1 output
capacitance to 0V.
Switch Pin 1 (Input): Inductor connection for the synchronous boost regulator. Connect the inductor
between VIN and SW1. Due to the high-speed switching on this pin, the SW1 pin should be routed away
from sensitive nodes and trace length should be kept as short and wide as possible to reduce EMI. If the
inductor current falls to zero, an internal anti-ringing switch is connected between the SW1 and VIN pins
to minimize the switch node ringing.
Exposed Pad (Power): Must make a full connection to a GND plane.
May 27, 2014
3
Revision 1.2