MIC2194 Micrel
MIC2194
400kHz SO-8 Buck Control IC
General Description Features
Micrels MIC2194 is a high efficiency PWM buck control IC 2.9V to 14V input voltage range
housed in the SO-8 package. Its 2.9V to 14V input voltage 400kHz oscillator frequency
range allows it to efficiently step down voltages in 3.3V, 5V, PWM current mode control
and 12V systems as well as 1- or 2-cell Li Ion battery powered 2 output drivers
applications. The flexible architecture of the MIC2194 allows 100% maximum duty cycle
for it to be configured as a buck or a buck-boost converter. 0.5 A micro-power shutdown
Programmable UVLO
The MIC2194 solution saves valuable board space. The
Front edge blanking
device is housed in the space-saving SO-8 package, whose
Cycle-by-cycle current limiting
low pin-count minimizes external components. Its 400kHz
Frequency foldback short circuit protection
PWM operation allows a small inductor and small output
8-lead SOIC package
capacitors to be used. The MIC2194 can implement all-
ceramic capacitor solutions.
Applications
The MIC2194 drives a high-side P-channel MOSFET. A low
Point of load power supplies
output driver impedance of 2 allows the MIC2194 to drive
Negative voltage buck-boost power supplies
large external MOSFETs to generate a wide range of output
Distributed power systems
currents. The MIC2194 can achieve maximum duty cycles of
Base stations
100%, which can be useful in low headroom applications.
Wireless modems
The MIC2194 is available in an 8 pin SOIC package with a
ADSL line cards
junction temperature range of 40C to +125C.
Servers
Step down conversion in 3.3V, 5V, 12V systems
1-and 2-cell Li Ion battery operated equipment
Typical Application
V
IN
12V
0.012
47 F MIC2194BM
Si4431A
20V
(2)
VIN CS
(2)
V
OUT
EN/
OUTP 5.2 H 5V, 5A
UVLO
VDD FB
10k
B530
1 F
2k
COMP GND 220 F
2.2nF
10V
3.32k
(2)
Adjustable Output Buck Converter
V
IN
+3.3V
22 H
0.040
Si9803
10 F MIC2194BM
16V
22nF
VIN CS
B530
EN/
OUTP 220 F
3.01k
UVLO
10 F 10V
16V (2)
VDD FB
1 F
4.99k
1k
COMP GND
10nF
V
OUT
5V, 0.6A
Positive-to-Negative Buck-Boost Converter
Micrel, Inc. 2180 Fortune Drive San Jose, CA 95131 USA tel + 1 (408) 944-0800 fax + 1 (408) 474-1000 MIC2194 Micrel
Ordering Information
Part Number
Standard Lead-Free Output Voltage Frequency Junction Temp. Range Package
MIC2194BM MIC2194YM Adjustable 400kHz 40C to +125C 8-lead SOP
Pin Configuration
COMP 1 8 VIN
FB 2 7 OUTP
EN/UVLO 3 6 GND
CS 4 5 VDD
8 Lead SOIC (M)
Pin Description
Pin Number Pin Name Pin Function
1 COMP Compensation (Output): Internal error amplifier output. Connect to a
capacitor or series RC network to compensate the regulators control loop.
2 FB Feedback (Input): The circuit regulates this pin to 1.245V.
3 EN/UVLO Enable/Undervoltage Lockout (Input): A low level on this pin will power down
the device, reducing the quiescent current to under 0.5 A. This pin has two
separate thresholds, below 1.5V the output switching is disabled, and below
0.9V the device is forced into a complete micropower shutdown. The 1.5V
threshold functions as an accurate undervoltage lockout (UVLO) with
hysteresis.
4 CS The () input to the current limit comparator. A built-in offset of 110mV
between VIN and CSL in conjunction with the current sense resistor sets the
current limit threshold level. This is also the () input to the current amplifier.
5 VDD 3V internal linear-regulator output. VDD is also the supply voltage bus for the
chip. Bypass to GND with 1 F.
6 GND Ground.
7 OUTP High current drive for the synchronous N-channel MOSFET. Voltage swing
is from ground to VIN. On-resistance is typically 3 @ 5V .
IN
8 VIN Input voltage to the circuit. Also the high side input to the current sense
amplifier supplies power to the gate drive circuit.
MIC2194 2 April 2005