MIC2184YM TR Micrel Inc, MIC2184YM TR Datasheet - Page 8

• Manufacturer Part Number: MIC2184YM TR
• Description: SO-16 Low Vin Buck PWM Control IC ( )
• Manufacturer: Micrel Inc

Specifications of MIC2184YM TR

• Pwm Type: Current Mode
• Number Of Outputs: 1
• Frequency - Max: 440kHz
• Duty Cycle: 100%
• Voltage - Supply: 2.9 V ~ 14 V
• Buck: Yes
• Boost: No
• Flyback: No
• Inverting: No
• Doubler: No
• Divider: No
• Cuk: No
• Isolated: No
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 16-SOIC (3.9mm Width)
• Frequency-max: 440kHz
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: MIC2184YMTR; MIC2184YMTR

MIC2184
Functional Diagram
Functional Characteristics
Controller Overview and Functional Description
The MIC2184 is a BiCMOS, switched mode, synchronous,
step down (buck) converter controller. It uses a P-Channel
MOSFET, which allows the controller to operate at 100% duty
cycle and eliminates the need for a high side drive bootstrap
circuit. Current mode control is used to achieve superior
transient line and load regulation. An internal corrective ramp
provides slope compensation for stable operation above a
50% duty cycle. The controller is optimized for high efficiency,
high performance DC-DC converter applications.
Figure 1 is a block diagram of the MIC2184 configured as a
synchronous buck converter. At the beginning of the switch-
ing cycle, the OUTP pin pulls low and turns on the high-side
M9999-042205
EN/UVLO
FREQ/2
FreqOut
COMP
SYNC
VREF
VDD
SS
7
10
11
15
2
3
4
13
÷2
OSC
V
fs/4
REF
COMPARATOR
C
DECOUP
VDD
PWM
COMPENSATION
RESET
VINA
CONTROL
SLOPE
BIAS
1
ON
Figure 1. MIC2184 Block Diagram
1.245V
VREF
fs/4
100k
∑
CURRENT
FREQUENCY
FOLDBACK
OVERCURRENT
SENSE
COMPARATOR
AMP
gm = 0.0002
gain = 20
8
ERROR
P-Channel MOSFET, Q1. Current flows from the input to the
output through the current sense resistor, MOSFET and
inductor. The current amplitude increases, controlled by the
inductor. The voltage developed across the current sense
resistor, R
bined with an internal ramp for stability. This signal is com-
pared to the output of the error amplifier. When the current
signal equals the error voltage signal, the P-channel MOSFET
is turned off. The inductor current flows through the diode, D1.
At the beginning of the next switching cycle, the P-channel
MOSFET is turned on which turns off the diode, D1.
AMP
GAIN
3.7
0.3V
V
0.1V
REF
16
14
12
9
8
6
5
CSH
CSL
VINP
OUTP
PGND
FB
SGND
SENSE
, is amplified inside the MIC2184 and com-
Q1
R
SENSE
C
IN
D1
V
L1
IN
C
OUT
Micrel, Inc.
April 2005
V
OUT