MIC2186BQS Micrel Inc, MIC2186BQS Datasheet - Page 8

• Manufacturer Part Number: MIC2186BQS
• Description: IC PWM BST FLYBCK CM 16QSOP
• Manufacturer: Micrel Inc

Specifications of MIC2186BQS

• Pwm Type: Current Mode
• Number Of Outputs: 1
• Frequency - Max: 440kHz
• Duty Cycle: 85%
• Voltage - Supply: 2.9 V ~ 14 V
• Buck: No
• Boost: Yes
• Flyback: Yes
• 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: Contains lead / RoHS non-compliant

MIC2186
M9999-042205
The description of the MIC2186 controller is broken
• Control Loop
• Current Limit
• MOSFET gate drive
• Reference, enable & UVLO
• Oscillator & Sync
• Soft start
down into 6 basic functions.
• PWM Operation
• SKIP Mode Operation
V
IN
V
DD
EN/UVLO
Soft Start
COMP
Freq/2
HiDC
SKIP
Sync
V
V
REF
13
15
11
10
DD
7
2
3
4
8
V
V
Figure 2. MIC2186 SKIP Mode Block Diagram
REF
DD
Osc
Control
C
DECOUP
S
Current
Reset
GND
S
On
GND
V
IN
5
Bias
A
1
Limit Comparator
Skip Current
8
Comparator
Control Loop
PWM and SKIP modes of operation
The MIC2186 can operate in either PWM (pulse width modu-
lated) or SKIP mode. The efficiency of the boost converter
can be improved at lower output loads by manually selecting
the skip mode of operation. The potential disadvantage of
skip mode is the variable switching frequency that accompa-
nies this mode of operation. The occurrence of switching
pulses depends on component values as well as line and load
conditions. PWM mode is the best choice of operation at
higher output loads. PWM mode has the advantages of lower
output ripple voltage and higher efficiencies at higher output
loads. Pulling the SKIP pin (pin 3) low will force the controller
to operate in PWM mode for all load conditions. Pulling the
SKIP pin high will force the controller to operate in SKIP
mode.
Hysteresis
V
V
50mV
±1%
REF
DD
1.245V
V
REF
P
C
GND
IN
P
GND
V
16
OutN
14
CSH
9
P
12
V
6
IN
GND
fb
P
L1
Q1
R
SENSE
D1
C
OUT
R1
R2
V
OUT
Micrel, Inc.
April 2005