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Buck Controller. MIC2198 Datasheet |
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MIC2198
MIC2198
Micrel, Inc.
500kHz 4mm × 4mm Synchronous Buck Controller
General Description
The MIC2198 is a high-power 500kHz synchronous buck
DC-to-DC controller housed in a small 4mm × 4mm MLF™
12-pin package. The MIC2198 operates from a wide 4.5V
to 32V input and can be programmed for output voltages
from 0.8V to 6V. The wide input voltage capability makes
the MIC2198 an ideal solution for point-of-load DC-to-DC
conversion in 5V, 12V and higher systems.
The 500kHz switching frequency allows the use of a small
inductor and small output capacitors. The current mode PWM
control along with the external COMP pin allows for ease of
stability compensation and fast transient response across a
wide range of applications.
An all N-Channel synchronous architecture and powerful
output drivers allow up to 20A of output current capability.
For higher efficiency at higher input voltages, refer to the
300kHz MIC2199.
The MIC2198 is available in a 12-pin 4mm × 4mm MLF™
package with a junction temperature range from –40°C to
125°C.
Features
• 4.5V to 32V input range
• 4mm × 4mm MLF™ package
• 500kHz PWM operation
• >90% efficiency
• Output voltage adjustable down to 0.8V
• 20A output current capability
• Drives all N-Channel MOSFETs
• Logic controlled micropower shutdown
• Cycle-by-cycle current limiting
• Adjustable undervoltage lockout
• Frequency foldback overcurrent protection
Applications
• Point-of-load DC-to-DC conversion from 5V, 12V
and higher supplies
• Telecom equipment
• Wireless modems
• Servers
• Base stations
Typical Application
VIN
5.5V to 24V
22µF
2kΩ
2.2nF
U1 MIC2198BML
VIN VDD
SD103BWS
4.7µF
EN/UVLO
BST
HSD
VSW
LSD
0.1µF
IRF7821
1µH
IRF7821
COMP
CSH
VOUT
1nF
GND
FB
0.01Ω
VOUT
3.3V/7A
220µF
10kΩ
6.04kΩ
5.5V–24V to 3.3V/7A Converter
Efficiency
vs. Load Current
100
95
90
85
80
75
70
65
60 VIN = 5.5V
55 VOUT = 3.3V
500 2 4 6
ILOAD (A)
8
MLF and MicroLeadFrame are trademarks of Amkor Technology, Inc.
Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
October 2005
1
MIC2198
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MIC2198
Ordering Information
Part Number
Standard
Pb-Free
MIC2198BML MIC2198YML
Voltage
Adj
Temperature Range
–40ºC to +125ºC
Package
12-Pin 4x4 MLF™
Micrel, Inc.
Pin Configuration
COMP
EN/UVLO
FB
CSH
VOUT
VIN
1
2
3
4
5
6
12 HSD
11 VSW
10 BST
9 GND
8 LSD
7 VDD
12-Pin 4×4 MLF (ML)
Pin Description
Pin Number
1
2
Pin Name
COMP
EN/UVLO
3 FB
4 CSH
5 VOUT
6 VIN
7 VDD
8 LSD
9 GND
10 BST
11 VSW
12 HSD
Pin Function
Compensation (Output): Internal error amplifier output. Connect to capacitor
or series RC network to compensate the regulator control loop.
Enable/Undervoltage Lockout (Input): Low-level signal powers down the
controller. Input below the 2.5V threshold disables switching and functions as
an accurate undervoltage lockout (UVLO). Input below the threshold forces
complete micropower (<0.1µA) shutdown.
Feedback (Input): Regulates FB pin to 0.8V. See “Applications Information”
for resistor divider calculations.
Current-Sense High (Input): Current limit comparator non-inverting input. A
built-in offset of 75mV between CSH and VOUT pins in conjunction with the
current-sense resistor set the current limit threshold level. This is also the
non-inverting input to the current sense amplifier.
Current-Sense Low (Input): Output voltage feedback input and inverting
input for the current limit comparator and the current sense amplifier.
Unregulated Input (Input): +4.5V to +32V supply input.
5V Internal Linear-Regulator (Output): VDD is the external MOSFET gate
drive supply voltage and internal supply bus for the IC. Bypass to GND with
4.7µF.
Low-Side Drive (Output): High-current driver output for low-side N-Channel
MOSFET. Voltage swing is between ground and VDD.
Ground (Return).
Boost (Input): Provides drive voltage for the high-side MOSFET driver. The
drive voltage is higher than the input voltage by VDD minus a diode drop.
Switch (Return): High-side MOSFET driver return.
High-Side Drive (Output): High-current driver output for high-side MOSFET.
This node voltage swing is between ground and VIN +5V minus a diode drop.
MIC2198
2 October 2005
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