MIC2159
SYNCHRONOUS-itty™ Step-Down
Converter IC
General Description
The MIC2159 is a high efficiency, simple to use
synchronous buck controller ICs housed in a 10-pin MSOP
ePAD package. The MIC2159 switches at 400kHz,
allowing the smallest possible external components and is
designed to drive loads up to 30A. The devices feature
high output driver capability, combined with an all n-
channel synchronous architecture.
The MIC2159 operates from a 3V to 14.5V input and can
be configured to generate output voltages as low as 0.8V.
Efficiencies of over 95% can be achieved within the
smallest possible printed circuit board space area.
The MIC2159 is available in a thermally capable 10-pin
ePAD MSOP package, with a junction operating range
from –40°C to +125°C.
Features
•
•
•
•
•
•
•
•
•
•
•
Small footprint 10-lead ePAD MSOP
3V to 14.5V input voltage range
Adjustable output voltage down to 0.8V
400KHz operation
Drives two n-channel MOSFETs
-
Built-in 3Ω drivers
Simple control: voltage-mode PWM
Fast transient response
-
Externally compensated
Over-current protection
Hiccup mode short-circuit protection
Dual function COMP & EN pin
-
I
SD
= 50µA
Short minimum ON time
-
30ns
-
Very low duty cycle possible
Applications
•
Point-of-Load DC/DC conversion
•
High Current Power Supplies
•
Telecom/datacom and Networking Power Supplies
•
Servers and Workstations
•
Graphics Cards and other PC Peripherals
___________________________________________________________________________________________________________
Typical Application
MIC2159 Adjustable Output 400kHz Converter
MLF and MicroLead Frame is a registered trademark 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
March 2009
M9999-030509-B
Micrel, Inc.
MIC2159
Ordering Information
Part Number
MIC2159YMME
Output Voltage
Adj
Frequency
400KHz
Juction Temperature Range
-40°C to +125°C
Package
10-pin ePAD MSOP
Pin Configuration
10-lead e-PAD MSOP (MME)
Pin Description
Pin Number
(MSOP-10)
1
2
3
4
5
6
7
8
9
Pin Name
V
IN
V
DD
CS
COMP/EN
FB
GND
LSD
VSW
HSD
Pin Function
Supply voltage (Input): 3V to 14.5V
5V Internal Linear Regulator (Output): V
DD
is the external MOSFET gate drive supply voltage
and an internal supply bus for the IC. When Vin is
≤5V,
V
DD
should be connected to Vin.
Current Sense. Current-limit comparator non-inverting input. The current limit is sensed across
the FET during the ON time. The current can be set by the resistor in series with the CS pin.
Compensation (Input): Dual function pin. Pin for external compensation. If this pin is pulled
below 0.2V, with the reference fully up the device shuts down (50μA typical current draw)
Feedback (Input): Input to error amplifier. Regulates error amplifier to 0.8V.
Ground (Return)
Low-Side Drive (Output): High-current driver output for external synchronous MOSFET.
Switch (Return): High-side MOSFET driver return
High-Side Drive (Output): High current output-driver for the high-side MOSFET.
When Vin is below 5v, 2.5v threshold FETs should be used. At Vin > 5V, 4.5V threshold FETs
should be used.
10
BST
Boost (Input): Provides the drive voltage for the high-side MOSFET driver. The gate drive
voltage is higher than the source voltage by V
IN
minus a diode drop.
March 2009
2
M9999-030509-B
Micrel, Inc.
MIC2159
Absolute Maximum Rating
(1)
Supply Voltage (V
IN
) ....................................................15.5V
Booststrapped Voltage (V
BST
) .................................. V
IN
+5V
Junction Temperature Range..............–40°C
≤
T
J
≤
+125°C
Ambient Storage Temp .............................–65°C to +150°C
Operating Ratings
(2)
Supply Voltage........................................... +3V to +14.5V
Output Voltage Range ............................ 0.8V to V
IN*
D
MAX
Package Thermal Resistance
θ
JA
10-lead ePAD MSOP................................63°C/W
Electrical Characteristics
Tj = 25ºC,
bold
values indicate -40ºC<Tj<+125ºC; Vin = 5V; unless otherwise specified
Parameter
Regulation
Feedback Voltage
Reference
Feedback Voltage
Reference
Feedback Bias Current
Output Voltage Line
Regulation
Output Voltage Load
Regulation
Output Voltage Total
Regulation
Oscillator Section
Oscillator Frequency
Maximum Duty Cycle
Minimum On-Time
Input and VDD Supply
PWM mode supply
current
Shutdown Quiescent
Current (MSOP-10)
V
COMP
Shutdown
Threshold (MSOP-10)
V
COMP
Shutdown
Blanking Period (MSOP-
10)
Digital Supply Voltage
(V
DD
)
Error Amplifier
DC Gain
Transconductance
Soft Start
Soft Start Current
Current Sense
Current Sense Over
Current Trip Point
Temperature Coefficient
135
200
2300
275
µA
ppm/°C
Condition
(+/- 1%)
(+/- 2% over temp)
Min
0.792
0.784
Typ
0.8
0.8
150
0.03
0.5
Max
0.808
0.816
350
Units
V
V
nA
%/V
%
3V
≤
VIN
≤
14.5V; 1A
≤
IOUT
≤
10A
(VOUT = 2.5V) Note 3
350
92
Note 3
V
CS/EN
=Vin- 0.25V; V
FB
= 0.7V
(output switching but excluding external MOSFET gate
current.)
V
COMP
= 0V
0.1
1
V
IN
>6V
4.7
0.6
1.5
%
400
30
1.6
450
60
3
kHz
%
ns
mA
50
0.25
4
5
150
0.35
8
5.3
µA
V
ms
V
70
1.4
After time out of internal timer
-13
9
-4
dB
mS
µA
March 2009
3
M9999-030509-B
Micrel, Inc.
Parameter
Upper Threshold,
V
FB_OVT
Lower Threshold,
V
FB_UVT
Gate Drivers
Rise/Fall Time
Into 3000pF at V
IN
> 5V
Source, V
IN
= 4.5V
Sink, V
IN
= 4.5V
Output Driver Impedance
Source, V
IN
= 3V
Sink, V
IN
= 3V
Driver Non-overlap Time
Notes:
1. Exceeding the absolute maximum rating may damage the device.
2. The device is not guaranteed to function outside its operating rating.
3. Guaranteed by design
4. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF.
5. Specification for packaged product only.
MIC2159
Condition
Min
2
-2
Typ
3.5
-3.5
Max
5
-5
Units
%
%
Output Fault Correction Thresholds
15
2.5
2.5
3
3
50
3
3
ns
Ω
4
4
ns
Note 3
March 2009
4
M9999-030509-B
Micrel, Inc.
MIC2159
Typical Characteristics
March 2009
5
M9999-030509-B
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