Micrel, Inc.
MIC2199
MIC2199
300kHz 4mm
×
4mm Synchronous Buck Converter
General Description
The MIC2199 is a high-power 300kHz synchronous buck
DC-to-DC controller housed in a small 4mm
×
4mm MLF™
12-pin package. The MIC2199 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 MIC2199 an ideal solution for point-of-load DC-to-DC
conversion in 5V, 12V, 24V, and 28V systems.
The 300kHz 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 smaller external components, refer to the 500kHz
MIC2198.
The MIC2199 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
300kHz PWM operation
95% 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,
24V, 28V supplies
• Telecom equipment
• Wireless modems
• Servers
• Base stations
Typical Application
V
IN
4.5V to 24V
U1 MIC2199BML
22µF
SD103BWS
4.7µF
0.1µF
IRF7821
2µH
IRF7821
1nF
10kΩ
6.04kΩ
100.0
VIN
VDD
BST
EN/UVLO
HSD
VSW
LSD
CSH
0.01Ω
V
OUT
3.3V/7A
220µF
95.0
COMP
2kΩ
GND
2.2nF
VOUT
FB
90.0
V
OUT
= 3.3V
2
4
I
LOAD (A)
6
8
85.0
0
4.5V–24V to 3.3V/7A Converter
Efficiency for
V
IN
= 5V and V
OUT
= 3.3V
MLF and
MicroLeadFrame
are registered 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
January 2010
1
M9999-011310
Micrel, Inc.
MIC2199.
Ordering Information
Part Number
Standard
MIC2199BML
Pb-Free
MIC2199YML
Voltage
Adj
Temperature Range
−40ºC to +125ºC
Package
12-Pin 4x4 MLF
®
Pin Configuration
COMP
EN/UVLO
FB
CSH
VOUT
VIN
1
12
HSD
VSW
BST
GND
LSD
VDD
2
3
11
10
4
5
6
9
8
7
12-Pin 4×4 MLF
®
(ML)
Pin Description
Pin Number
1
2
Pin Name
COMP
EN/UVLO
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 100mV between CSH and V
OUT
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): V
DD
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 V
DD
.
3
4
FB
CSH
5
6
7
VOUT
VIN
VDD
8
9
LSD
GND
BST
VSW
HSD
Ground (Return).
10
11
12
Switch (Return): High-side MOSFET driver return.
Boost (Input): Provides drive voltage for the high-side MOSFET driver. The
drive voltage is higher than the input voltage by V
DD
minus a diode drop.
High-Side Drive (Output): High-current driver output for high-side MOSFET.
This node voltage swing is between ground and V
IN
+5V minus a diode drop.
January 2010
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M9999-011310
Micrel, Inc.
MIC2199
Absolute Maximum Ratings
(Note 1)
Analog Supply Voltage (V
IN
)........................................
+34V
Digital Supply Voltage (V
DD
)..........................................
+7V
Driver Supply Voltage (B
ST
) ...................................V
IN
+ 7V
Sense Voltage (V
OUT
, C
SH
) ...............................7V to –0.3V
Enable Pin Voltage (V
EN/UVLO
) ....................................... V
IN
Power Dissipation (P
D
)
4×4 MLF™ ..................................665mW @ T
A
= 85°C
Ambient Storage Temperature (T
S
) ..........
–65°C to +150°C
ESD, Note
3
Operating Ratings
(Note 2)
Analog Supply Voltage (V
IN
).........................
+4.5V to +32V
Output Voltage Range (V
OUT
) .......................
+0.8V to +6V
Junction Temperature (T
J
) ........................
–40°C to +125°C
Package Thermal Resistance
4×4 MLF-12L (θ
JA
) ............................................... 60°C/W
Electrical Characteristics
(Note 4)
Parameter
V
IN
= V
EN
= 12V; T
J
= 25°C, unless noted,
bold values indicate –40°C ≤ T
J
≤ +125°C
Condition
(±1%)
(±2%)
4.5V < V
IN
< 32V, 0 < (V
CSH
– V
OUT
) < 60mV (±3%)
Min
0.792
0.784
0.776
0.8
25mV < (V
CSH
– V
OUT
) < 60mV
V
IN
= 4.5V to 32V, V
CSH
– V
OUT
= 60mV
4.7
3.95
0.6
2.2
V
EN/UVLO
= 5V
(V
CSH
– V
OUT
)
55
270
measured at V
OUT
pin
80
0.25
0.03
0.5
1.6
0.1
5.0
4.25
4.1
1.1
2.5
0.1
75
0.2
300
85
170
0.40
75
60
5
3.5
80
8.5
6
1.6
2.8
5
95
330
200
0.55
10
Typ
0.8
Max
0.808
0.816
0.824
6
2.5
5
5.3
4.4
Units
V
V
V
nA
V
%/V
%
mA
µA
V
V
V
V
V
µA
mV
mS
kHz
%
ns
V
kHz
ns
Ω
Ω
ns
Feedback Voltage Reference
Feedback Voltage Reference
Feedback Voltage Reference
Feedback Bias Current
Output Voltage Range
Output Voltage Line Regulation
Output Voltage Load Regulation
Quiescent Current
Input and V
DD
Supply
excluding external MOSFET gate drive current
I
L
= 0mA to 5mA
V
EN/UVLO
= 0V
Shutdown Quiescent Current
Undervoltage Lockout
Enable/UVLO
Enable Input Threshold
UVLO Threshold
Enable Input Current
Current Limit
Current Limit Threshold Voltage
Error Amplifier
Oscillator Section
Oscillator Frequency
Maximum Duty Cycle
Minimum On-Time
Frequency Foldback Threshold
Foldback Frequency
Gate Drivers
Rise/Fall Time
Output Driver Impedance
Driver Non-Overlap Time
Note 1.
Note 2.
Note 3.
Digital Supply Voltage (V
DD
)
V
IN
lower threshold (turn-off threshold)
V
IN
upper threshold (turn-on threshold)
Transconductance Error Amplifier GM
C
L
= 3000pF
source
sink
Exceeding the absolute maximum rating may damage the device.
The device is not guaranteed to function outside its operating rating.
Devices are ESD protected; however, handling precautions are recommended. Human body model, 1.5k in series with 100pF.
Note 4.
Specification for packaged product only.
January 2010
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M9999-011310
Micrel, Inc.
MIC2199
Typical Characteristics
Quiescent Current
vs. Temperature
PWM
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
4
Quiescent Current
vs. Supply
Voltage
P WM
0.820
0.818
0.816
0.814
V
FB
Line Regulation
UVLO
Shutdown
UVLO
Shutdown
9 14 19 24 29 34
SUPPLY VOLTAGE (V)
0.812
0.810
0.808
0
5 10 15 20 25 30
SUPPLY VOLTAGE (V)
35
0
-40 -20 0 20 40 60 80 100120140
TEMPERATURE (°C)
0.82
0.818
0.816
0.814
0.812
0.810
0.808
0.806
0.804
0.802
V
FB
vs. Temperature
6.0
5.0
4.0
3.0
2.0
1.0
0
0
4
V
DD
Line Regulation
5.02
5.01
5.00
4.99
4.98
4.97
4.96
4.95
4.94
V
DD
Load
Regulation
0.8
-40 -20 0 20 40 60 80 100120140
TEMPERATURE (°C)
8 12 16 20 24 28 32
SUPPLY VOLTAGE (V)
0
5
10 15 20 25
LOAD CURRENT (mA)
30
5.20
5.15
5.10
5.05
5.00
4.95
4.90
4.85
V
DD
vs. Temperature
4.80
-40 -20 0 20 40 60 80 100120140
TEMPERATURE (°C)
10
8
6
4
2
0
-2
-4
-6
-8
-10
-40 -20 0 20 40 60 80 100120140
TEMPERATURE (°C)
Oscillator Frequency
vs. Temperature
0.25
0.20
0.15
0.10
0.05
0.00
-0.05
-0.10
-0.15
0
Oscillator Frequency
vs. Supply
Voltage
5 10 15 20 25 30
SUPPLY VOLTAGE (V)
35
78
76
74
72
70
68
66
Overcurrent Threshold
vs. Temperature
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
0
Current
Limit
Foldback
V
IN
= 5V
V
OUT
= 3.3V
R
C S
= 20mV
64
-40 -20 0 20 40 60 80 100120140
TEMPERATURE (°C)
1
2
3
4
OUTPUT CURRENT (A)
5
January 2010
4
M9999-011310
Micrel, Inc.
MIC2199.
V
IN
C
IN
Block Diagram
EN/UVLO
2
V
DD
VDD
7
Reference
V
BG
0.8V
VIN
V
IN
6
D2
4.7µF
BST
10
Control
Logic
HSD
12
VSW
11
Q2
C
BST
L1
D1
R
CS
V
OUT
C
OUT
LSD
8
PGND
9
Q1
Current
Limit
PWM OUTPUT
PWM
RESET
CORRECTIVE
RAMP
Current
Sense
Amp
CSH
4
V
BG
A
V
= 2
VOUT
5
Oscillator
COMP
C
COMP
R
COMP
MIC2199
1
Error
Amp
100k
R1
FB
3
G
m
= 0.2×10
-3
V
OUT
= 0.8V
1
+
R1
R2
V
OUT(max)
= 6.0V
R2
Figure 1. Internal Block Diagram
Functional Description
The MIC2199 is a BiCMOS, switched-mode, synchronous
step-down (buck) converter controller. 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.
The MIC2199 block diagram is shown above.
The MIC2199 controller is divided into 5 functions.
• Control loop
• Current limit
• Reference, enable and UVLO
• MOSFET gate drive
• Oscillator
Control Loop
The MIC2199 operates in PWM (pulse-width-modulation)
mode. In PWM mode, the synchronous buck converter
forces continuous current to flow in the inductor which also
improves cross regulation of transformer coupled, multiple
output configurations.
PWM Control Loop
The MIC2199 uses current-mode control to regulate the output
voltage. This method senses the output voltage (outer loop)
and the inductor current (inner loop). It uses inductor current
and output voltage to determine the duty cycle of the buck
converter. Sampling the inductor current removes the inductor
from the control loop, which simplifies compensation.
A block diagram of the MIC2199 PWM current-mode control
loop is shown in Figure 2 and the PWM mode voltage and
current waveform is shown in Figure 3. The inductor current
is sensed by measuring the voltage across the resistor, R
CS
.
January 2010
5
M9999-011310
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