MIC2166 Datasheet, PDF (2/26 Pages) Micrel Semiconductor – Adaptive On-Time DC-DC Controller

Micrel, Inc.
Ordering Information
Part Number
MIC2166YMME
Voltage
Adj.
Switching Frequency
600kHz
Junction Temp. Range
–40° to +125°C
Package
10-pin ePad MSOP
Pin Configuration
MIC2166
Lead Finish
Pb-Free
10-Pin ePad MSOP (MME)
Pin Description
Pin
Number
1
2
3
4
5
6
7
8
9
10
EP
Pin Name Pin Function
FB
PGOOD
EN
VIN
VDD
DL
PGND
DH
SW
BST
GND
Feedback (input): Input to the transconductance amplifier of the control loop. The FB pin is regulated to
0.8V. A resistor divider the output an FB is used to set the desired output voltage.
Power Good (Output): Open Drain Output. The PGOOD pin is externally tied with a resistor to VDD.
High output when VOUT>90% nominal.
Enable (input): A logic level control of the output. The EN pin is CMOS-compatible. Logic high = enable,
logic low = shutdown. In the off state, supply current of the device is greatly reduced (typically 5µA). The
EN pin should not be left open. Connect to VIN if sequencing is not required.
Supply Voltage: Input voltage for the internal +5V linear regulator. The VIN operating voltage range is
from 4.5V to 28V. A 0.1µF capacitor between VIN and the ground is required.
5V Internal Linear Regulator (Output): VDD is the external MOSFET gate drive supply voltage and an
internal supply bus for the IC. VDD is created by internal LDO from VIN. When VIN <+5.5V, VDD Should
be tied to VIN. A 2.2µF (minimum) ceramic capacitor from VDD to GND is recommended for clean
operation.
Low-Side Gate Drive (output): High-current driver output for external low-side MOSFET. The DL driving
voltage swings from ground to VDD.
Power Ground. PGND is the ground path for the MIC2166 buck converter power stage. The PGND pin
connects to the sources of low-side N-Channel MOSFETs, the negative terminals of input capacitors,
and the negative terminals of output capacitors. The loop for the power ground should be as small as
possible and separate from the Signal ground (GND) loop.
High-Side Gate Drive (output): High-current driver output for external high-side MOSFET. The DH
driving voltage is floating on the switch node voltage (SW). It swings from ground-to-VDD minus the
diode drop.
Switch Node (input): High current output driver return. The SW pin connects directly to the switch node.
Due to the high speed switching on this pin, the SW pin should be routed away from sensitive nodes.
Current Sense input (input): SW pin also senses the current by monitoring the voltage across the low-
side MOSFET during OFF-time. The current sensing is necessary for short circuit protection. In order to
sense the current accurately, connect the low-side MOSFET drain to SW using a Kelvin connection.
Boost (output): Bootstrapped voltage to the high-side N-channel MOSFET driver. A Schottky diode is
connected between the VDD pin and the BST pin. A boost capacitor of 0.1μF is connected between the
BST pin and the SW pin. Adding a small resistor at BST pin can slow down the turn-on time of high-side
N-Channel MOSFETs.
Thermal Pad and Signal ground. GND is the ground path for VDD and the control circuitry. The loop for
the signal ground should be separate from the power ground (PGND) loop.
June 2010
2
M9999-060810-B