MIC3205 Datasheet, PDF (2/23 Pages) Micrel Semiconductor – High-Brightness LED Driver Controller with Fixed-Frequency Hysteretic Control

Micrel, Inc.
MIC3205
Ordering Information
Part Number
Junction Temperature Range
Package⁽¹⁾
MIC3205YML
40°C to 125°C
10-Pin 3mm x 3mm MLF
Note:
1. MLF is a GREEN RoHS-compliant package. Lead finish is NiPdAu. Mold compound is Halogen Free.
Pin Configuration
10-Pin 3mm x 3mm MLF (ML)
Top View
Pin Description
Pin Number
1
2
3
4
5
6
7
8
9
10
EP
Pin Name
VCC
CS
VIN
VINS
AGND
EN
DIM
CTIMER
PGND
DRV
ePAD
Pin Function
Voltage Regulator Output. The VCC pin is the output of a linear regulator powered from VIN, which
supplies power to the internal circuitry. A 4.7µF ceramic capacitor is recommended for bypassing. Place
it as close as possible to the VCC and AGND pins. Do not connect to an external load.
Current Sense Input. Negative input to the current sense comparator. Connect an external sense
resistor to set the LED current. Connect the current sense resistor as close as possible to the chip.
Input Power Supply. VIN is the input supply pin to the internal circuitry. Due to high frequency switching
noise, a 10µF ceramic capacitor is recommended for bypassing and should be placed as close as
possible to the VIN and PGND pins. See “PCB Layout Guidelines.”
VIN Sense. Positive input to the current sense comparator. Connect as close as possible to the current
sense resistor.
Analog Ground. Ground for all internal low-power circuitry.
Enable Input. Logic high (greater than 2V) powers up the regulator. A logic low (less than 0.4V) powers
down the regulator and reduces the supply current of the device to less than 2µA. A logic low pulls down
the DRV pin turning off the external MOSFET. Do not drive the EN pin above VIN. Do not leave floating.
PWM Dimming Input. A PWM input can be used to control the brightness of the LED. Logic high (greater
than 2V) enables the output. Logic low (less than 0.4V) disables the output regardless of the EN state.
Do not drive the DIM pin above VIN. Do not leave floating.
Timer Capacitor. A capacitor is required from CTIMER to ground sets the target switching frequency
using the equation C_TIMER=2.22*10^-4 / F_SW
Power Ground. Ground for the power MOSFET gate driver. The current loop for the power ground
should be as small as possible and separate from the analog ground loop. See “PCB Layout
Recommendations.”
Gate Drive Output. Connect to the gate of an external N-channel MOSFET. The drain of the external
MOSFET connects directly to the inductor and provides the switching current necessary to operate in
hysteretic mode.
Exposed Pad. Must be connected to a GND plane for best thermal performance.
October 2012
2
M9999-102312-A