MIC2176-1/-2/-3
Wide Input Voltage, Synchronous Buck
Controllers Featuring Adaptive On-Time
Control
Hyper Speed Control™ Family
General Description
The Micrel MIC2176-1/-2/-3 is a family of constant-frequency,
synchronous buck controllers featuring a unique digitally
modified adaptive ON-time control architecture. The MIC2176
family operates over an input supply range of 4.5V to 75V
and can be used to supply up to 15A of output current. The
output voltage is adjustable down to 0.8V with a guaranteed
accuracy of ±1%, and the device operates at a constant
switching frequency of 100kHz, 200kHz, and 300kHz.
Micrel’s Hyper Speed Control
TM
architecture allows for ultra-
fast transient response while reducing the output capacitance
and also makes (High V
IN
)/(Low V
OUT
) operation possible.
This digitally modified adaptive t
ON
ripple control architecture
combines the advantages of fixed-frequency operation and
fast transient response in a single device.
The MIC2176 offers a full suite of protection features to
ensure protection of the IC during fault conditions. These
include undervoltage lockout to ensure proper operation
under power-sag conditions, internal soft-start to reduce
inrush current, fold-back current limit, “hiccup” mode short-
circuit protection and thermal shutdown.
All support documentation can be found on Micrel’s web
site at:
www.micrel.com.
Features
•
Hyper Speed Control
TM
architecture enables
-
High delta V operation (V
IN
= 75V and V
OUT
= 1.2V)
-
Small output capacitance
4.5V to 75V input voltage
Output down to 0.8V with ±1% accuracy
Any Capacitor
TM
Stable
-
Zero-ESR to high-ESR output capacitance
100kHz/200kHz/300kHz switching frequency
Internal compensation
6ms Internal soft-start
Foldback current limit and “hiccup” mode short-circuit
protection
Thermal shutdown
Supports safe start-up into a pre-biased output
–40°C to +125°C junction temperature range
Available in 10-pin MSOP package
•
•
•
•
•
•
•
•
•
•
•
Applications
•
Distributed power systems
•
Networking/Telecom Infrastructure
•
Printers, scanners, graphic cards and video cards
___________________________________________________________________________________________________________
Typical Application
Efficiency
vs. Output Current
95
90
EFFICIENCY (%)
85
80
75
70
65
60
55
50
45
40
0
1
2
3
4
5
MIC2176-2
V
OUT
= 3.3V
V
DD
= 5V LINEAR
28V
IN
48V
IN
60V
IN
OUTPUT CURRENT (A)
MIC2176-2 Adjustable Output 200KHz Buck Converter
Hyper Speed Control, SuperSwitcher II and Any Capacitor are trademarks of Micrel, Inc.
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
November 2010
M9999-111710-A
Micrel, Inc.
MIC2176
Ordering Information
Part Number
MIC2176-1YMM
MIC2176-2YMM
MIC2176-3YMM
Output
Voltage
Adjustable
Adjustable
Adjustable
Switching Frequency
100kHz
200kHz
300kHz
Junction Temperature Range
–40°C to +125°C
–40°C to +125°C
–40°C to +125°C
Package
10-pin MSOP
10-pin MSOP
10-pin MSOP
Lead Finish
Pb-Free
Pb-Free
Pb-Free
Pin Configuration
10-Pin MSOP (MM)
Pin Description
Pin
Number
1
Pin Name
HSD
Pin Function
High-Side MOSFET Drain Connection (Input): The HSD pin in the input of the adaptive On-time
control circuitry. A 0.1uF ceramic capacitor between the HSD pin and the power ground (PGND) is
required and must be place as close as possible to the IC.
Enable (Input): A logic level control of the output. The EN pin is CMOS compatible. Logic high or
floating = enable, logic low = shutdown. In the off state, the V
DD
supply current of the device is
reduced (typically 0.7mA). Do not connect the EN pin to the HSD pin.
Feedback (Input): Input to the transconductance amplifier of the control loop. The FB pin is regulated
to 0.8V. A resistor divider connecting the feedback to the output is used to adjust the desired output
voltage.
Signal ground. GND is the ground path for the device bias voltage V
DD
and the control circuitry. The
loop for the signal ground should be separate from the power ground (PGND) loop.
V
DD
Bias (Input): Power to the internal reference and control sections of the MIC2176. The V
DD
operating voltage range is from 4.5V to 5.5V. A 1µF ceramic capacitor from the VDD pin to the PGND
pin must be placed next to the IC.
Low-Side Drive (output): High-current driver output for external low-side MOSFET. The DL driving
voltage swings from ground to V
DD
.
Power Ground. PGND is the ground path for the buck converter power stage. The PGND pin
connects to the sources of low-side N-Channel external MOSFETs, the negative terminals of input
capacitors, and the negative terminals of output capacitors. The loop for the power ground should be
as small as possible and separate from the Signal ground (GND) loop.
High-Side Drive (output): High-current driver output for external high-side MOSFET. The DH driving
voltage is floating on the switch node voltage (V
SW
). Adding a small resistor between DH pin and the
gate of the high-side N-channel MOSFETs can slow down the turn-on and turn-off time of the
MOSFETs.
2
EN
3
4
5
6
FB
GND
VDD
DL
7
PGND
8
DH
November 2010
2
M9999-111710-A
Micrel, Inc.
MIC2176
Pin Description (Continued)
Pin
Number
Pin Name
Pin Function
Switch Node and Current-Sense input (Input): High current output driver return. The SW pin connects
directly to the switch node. Due to the high-speed switching on this pin, the SW pin should be routed
away from sensitive nodes. The SW pin also senses the current by monitoring the voltage across the
low-side MOSFET during OFF time. In order to sense the current accurately, connect the low-side
MOSFET drain to the SW pin using a Kelvin connection.
Boost (Output): Bootstrapped voltage to the high-side N-channel internal MOSFET driver. A Schottky
diode is connected between the VDD pin and the BST pin. A boost capacitor of 0.1μF is connected
between the BST pin and the SW pin. Adding a small resistor in series with the BST pin can slow
down the turn-on time of high-side N-Channel MOSFETs.
9
SW
10
BST
November 2010
3
M9999-111710-A
Micrel, Inc.
MIC2176
Absolute Maximum Ratings
(1, 2)
V
HSD
to PGND................................................
−0.3V
to +76V
V
DD
to PGND ...................................................
−0.3V
to +6V
V
SW
to PGND......................................−0.3V to (V
HSD
+0.3V)
V
BST
to V
SW
........................................................
−0.3V
to 6V
V
BST
to PGND ..................................................
−0.3V
to 82V
V
EN
to PGND ......................................
−0.3V
to (V
DD
+ 0.3V)
V
FB
to PGND.......................................
−0.3V
to (V
DD
+ 0.3V)
PGND to GND ..............................................
−0.3V
to +0.3V
Junction Temperature .............................................. +150°C
Storage Temperature (T
S
).........................−65°C to +150°C
Lead Temperature (soldering, 10sec)........................ 260°C
Operating Ratings
(3)
Supply Voltage (V
HSD
) ....................................... 4.5V to 75V
Bias Voltage (V
DD
)............................................ 4.5V to 5.5V
Enable Input (V
EN
) ................................................. 0V to V
DD
Junction Temperature (T
J
) ........................
−40°C
to +125°C
Junction Thermal Resistance
MSOP (θ
JA
) ..................................................130.5°C/W
Continuous Power Dissipation
(derate 5.6mW/°C above 70°C)
(T
A
= 70°C) ........................................................421mW
ESD (Human Body Mode) .......................................... 1.5kV
Electrical Characteristics
(4)
V
IN
= V
HSD
= 48V, V
DD
= 5V; V
BST
– V
SW
= 5V; T
A
= 25°C, unless noted.
Bold
values indicate
−40°C
≤
T
J
≤
+125°C.
Parameter
Power Supply Input
HSD Voltage Range (V
HSD
)
(5)
V
DD
Bias Voltage
Operating Bias Voltage (V
DD
)
Undervoltage Lockout Trip Level
UVLO Hysteresis
Quiescent Supply Current
Shutdown Supply Current
Reference
Feedback Reference Voltage
FB Bias Current
Enable Control
EN Logic Level High
EN Logic Level Low
EN Bias Current
Oscillator
MIC2176-1
Switching Frequency
(6)
Condition
Min.
Typ.
Max.
Units
4.5
4.5
V
DD
Rising
V
FB
= 1.5V
SW = unconnected, V
EN
= 0V
0°C
≤
T
J
≤
85°C (±1.0%)
-40°C
≤
T
J
≤
125°C (±1.5%)
V
FB
= 0.8V
4.5V < V
DD
< 5.5V
4.5V < V
DD
< 5.5V
V
EN
= 0V
75
150
225
1.2
0.792
0.788
3.2
5
3.85
370
1.4
0.7
0.8
0.8
5
0.85
0.78
50
100
200
300
96
93
89
0
360
60
75
5.5
4.45
3
2
0.808
0.812
500
V
V
V
mV
mA
mA
V
nA
V
0.4
100
125
250
375
V
µA
MIC2176-2
MIC2176-3
MIC2176-1, V
FB
= 0V, HSD=4V, V
O
= 3.3V
kHz
Maximum Duty Cycle
(7)
Minimum Duty Cycle
Minimum Off-Time
Minimum On-Time
MIC2176-2, V
FB
= 0V, HSD=4V, V
O
= 3.3V
MIC2176-3, V
FB
= 0V, HSD=4V, V
O
= 3.3V
V
FB
> 0.8V
%
%
ns
ns
November 2010
4
M9999-111710-A
Micrel, Inc.
MIC2176
Electrical Characteristics
(4)
(Continued)
V
IN
= V
HSD
= 48V, V
DD
= 5V; V
BST
– V
SW
= 5V; T
A
= 25°C, unless noted.
Bold
values indicate
−40°C
≤
T
J
≤
+125°C.
Parameter
Condition
Min.
Typ.
Soft Start
Soft-Start time
Short Circuit Protection
Current-Limit Threshold
Short-Circuit Threshold
FET Drivers
DH, DL Output Low Voltage
DH, DL Output High Voltage
DH On-Resistance, High State
DH On-Resistance, Low State
DL On-Resistance, High State
DL On-Resistance, Low State
SW Leakage Current
HSD Leakage Current
Thermal Protection
Over-Temperature Shutdown
Over-Temperature Shutdown Hysteresis
Notes:
1. Exceeding the absolute maximum rating may damage the device.
2. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5kΩ in series with 100pF.
3. The device is not guaranteed to function outside operating range.
4. Specification for packaged product only.
5. The application is fully functional at low V
DD
(supply of the control section) if the external MOSFETs have enough low voltage V
TH
.
6. Measured in test mode.
7. The maximum duty-cycle is limited by the fixed mandatory off-time t
OFF
of typically 360ns.
Max.
Units
6
V
FB
= 0.8V
V
FB
= 0V
I
SINK
= 10mA
V
DD
- 0.1V
I
SOURCE
= 10mA
Or
V
BST
- 0.1V
2.1
1.8
1.8
1.2
V
SW
= 48V, V
DD
= 5V, V
BST
= 53V
V
SW
= 48V, V
DD
= 5V, V
BST
= 53V
T
J
Rising
160
25
3.3
3.3
3.3
2.3
55
55
103
19
130
48
162
77
0.1
ms
mV
mV
V
V
Ω
Ω
Ω
Ω
µA
µA
°C
°C
November 2010
5
M9999-111710-A
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