MIC2185YQS Micrel Inc, MIC2185YQS Datasheet - Page 14

• Manufacturer Part Number: MIC2185YQS
• Description: SO-16 Low Vin Synchronous Buck PWM Control IC ( )
• Manufacturer: Micrel Inc

Specifications of MIC2185YQS

• Pwm Type: Current Mode
• Number Of Outputs: 1
• Frequency - Max: 440kHz
• Duty Cycle: 95%
• Voltage - Supply: 2.9 V ~ 14 V
• Buck: No
• Boost: Yes
• Flyback: No
• Inverting: No
• Doubler: No
• Divider: No
• Cuk: No
• Isolated: No
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 16-QSOP
• Frequency-max: 440kHz
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 576-2162; MIC2185YQS

The significant contributors to power loss at higher output
loads are (in approximate order of magnitude):
To minimize power loss under heavy loads:
MIC2185
• Use a ferrite material for the inductor core, which
• Resistive on-time losses in both MOSFETs
• Switching transition losses in the low side MOS-
• Inductor resistive losses
• Current sense resistor losses
• Output capacitor resistive losses (due to the
• Use logic level, low on-resistance MOSFETs.
• Slow transition times and oscillations on the
• For the same size inductor, a lower value will
• Lowering the current sense resistor value will
• Use low ESR output capacitors to minimize the
has less core loss than an MPP or iron power
core.
FET
capacitor’s ESR)
Multiplying the gate charge by the on-resistance
gives a figure of merit, providing a good balance
between switching and resistive power dissipa-
tion.
voltage and current waveforms dissipate more
power during the turn-on and turn-off of the
low side MOSFET. A clean layout will minimize
parasitic inductance and capacitance in the gate
drive and high current paths. This will allow the
fastest transition times and waveforms without
oscillations. Low gate charge MOSFETs will
switch faster than those with higher gate charge
specifications.
have fewer turns and therefore, lower winding
resistance. However, using too small of a value
will increase the inductor current and therefore
require more output capacitors to filter the output
ripple.
decrease the power dissipated in the resistor.
However, it will also increase the overcurrent
limit and may require larger MOSFETs and
inductor components to handle the higher cur-
rents.
power dissipated in the capacitor’s ESR.
14
October 2005