MIC24056
12V, 12A High-Efficiency Buck Regulator
SuperSwitcher II
General Description
Features
•
HyperLight Load efficiency – up to 80% at 10mA
The Micrel MIC24056 is a constant-frequency,
synchronous DC/DC buck regulator featuring adaptive on-
•
Hyper Speed Control architecture enables
time control architecture. The MIC24056 operates over a
−
High delta V operation (V
IN
= 19V and V
OUT
= 0.8V)
supply range of 4.5V to 19V. It has an internal linear
−
Small output capacitance
regulator which provides a regulated 5V to power the
•
Input voltage range: 4.5V to 19V
internal control circuitry. MIC24056 operates at a constant
600kHz switching frequency in continuous-conduction
•
Output current up to 12A
mode and can be used to provide up to 12A of output
•
Up to 95% efficiency
current. The output voltage is adjustable down to 0.8V.
•
Adjustable output voltage from 0.8V to 5.5V
®
Micrel’s HyperLight Load architecture provides the same
•
±1% FB accuracy
high efficiency and ultra-fast transient response as the
•
Any Capacitor™ stable
−
zero-to-high ESR
Hyper Speed Control architecture under medium to
•
600kHz switching frequency
heavy loads, but also maintains high efficiency under light
load conditions by transitioning to variable frequency,
•
Power good (PG) output
discontinuous mode operation.
•
Foldback current-limit and “hiccup” mode short-circuit
The MIC24056 offers a full suite of protection features to
protection
ensure protection of the IC during fault conditions. These
•
Safe start-up into pre-biased loads
include undervoltage lockout to ensure proper operation
•
–40°C to +125°C junction temperature range
under power-sag conditions, thermal shutdown, internal
•
Available in 28-pin 5mm
×
6mm QFN package
soft start to reduce the inrush current, foldback current-
limit and “hiccup” mode short-circuit protection. The
Applications
MIC24056 includes a power good (PG) output to allow
simple sequencing.
•
Servers, work stations
The 12A Hyper Speed Control part, MIC24055, is also
•
Routers, switches, and telecom equipment
available on Micrel’s web site.
•
Base stations
All support documentation can be found on Micrel’s web
site at:
www.micrel.com.
___________________________________________________________________________________________________________
Typical Application
Efficiency (VIN = 12V)
vs. Output Current
100
95
90
5.0V
3.3V
2.5V
1.8V
1.5V
1.2V
1.0V
0.9V
0.8V
EFFICIENCY (%)
85
80
75
70
65
60
55
50
0
3
6
9
12
VIN = 12V
15
OUTPUT CURRENT (A)
HyperLight Load is a registered trademark of Micrel, Inc.
Hyper Speed Control, SuperSwitcher II, and Any Capacitor are trademarks of Micrel, 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
December 2012
M9999-121012-A
Micrel, Inc.
MIC24056
Ordering Information
Part Number
MIC24056YJL
Switching Frequency
600kHz
Voltage
Package
Junction Temperature Range
−40°C
to +125°C
Lead Finish
Pb-Free
Adjustable 28-Pin 5mm × 6mm QFN
Pin Configuration
28-Pin 5mm x 6mm QFN (JL)
(Top View)
Pin Description
Pin Number
1
Pin Name
PVDD
Pin Function
5V Internal Linear Regulator Output. PVDD supply is the power MOSFET gate drive supply voltage
and created by internal LDO from VIN. When VIN
<
+5.5V, PVDD should be tied to PVIN pins. A
2.2µF ceramic capacitor from the PVDD pin to PGND (Pin 2) must be place next to the IC.
Power Ground. PGND is the ground path for the MIC24056 buck converter power stage. The
PGND pins connect to the low-side N-Channel internal MOSFET gate drive supply ground, the
sources of the 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 (SGND) loop.
No Connect.
Switch Node Output. Internal connection for the high-side MOSFET source and low-side MOSFET
drain. Due to the high-speed switching on this pin, the SW pin should be routed away from sensitive
nodes.
High-Side N-Internal MOSFET Drain Connection Input. The PVIN operating voltage range is from
4.5V to 19V. Input capacitors between the PVIN pins and the Power Ground (PGND) are required to
keep the connection short.
Boost Output. Bootstrapped voltage to the high-side N-channel MOSFET driver. A Schottky diode is
connected between the PVDD 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 at the BST pin can slow down the turn-on time
of high-side N-Channel MOSFETs.
2, 5, 6,
7, 8, 21
3
4, 9,
10, 11, 12
13,14,15,
16,17,18,19
PGND
NC
SW
PVIN
20
BST
December 2012
2
M9999-121012-A
Micrel, Inc.
MIC24056
Pin Description (Continued)
Pin Number
22
Pin Name
CS
Pin Function
Current Sense Input. The CS pin senses current by monitoring the voltage across the low-side
MOSFET during the OFF-time. The current sensing is necessary for short circuit protection. In order
to sense the current accurately, connect the low-side MOSFET drain to SW using a Kelvin
connection. The CS pin is also the high-side MOSFET’s output driver return.
Signal Ground. SGND must be connected directly to the ground planes. Do not route the SGND pin to
the PGND Pad on the top layer (see
PCB Layout Guidelines
for details).
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.
Power Good Output. Open Drain Output. The PG pin is externally tied with a resistor to VDD. A high
output is asserted when V
OUT
>
92% of nominal.
Enable Input. A logic level control of the output. The EN pin is CMOS-compatible. Logic high =
enable, logic low = shutdown. In the off state, supply current of the device is greatly reduced (typically
5µA). The EN pin should not be left floating.
Power Supply Voltage Input. Requires bypass capacitor to SGND.
5V Internal Linear Regulator Output. VDD supply is the power MOSFET gate drive supply voltage and
the supply bus for the IC. VDD is created by internal LDO from VIN. When VIN
<
+5.5V, VDD should
be tied to PVIN pins. A 1µF ceramic capacitor from the VDD pin to SGND pins must be place next to
the IC.
23
24
25
26
27
28
SGND
FB
PG
EN
VIN
VDD
December 2012
3
M9999-121012-A
Micrel, Inc.
MIC24056
Absolute Maximum Ratings
(1)
PVIN to PGND...............................................
−0.3V
to +29V
VIN to PGND .................................................
−0.3V
to PVIN
PVDD, VDD to PGND .....................................
−0.3V
to +6V
V
SW
, V
CS
to PGND .............................
−0.3V
to (PVIN +0.3V)
V
BST
to V
SW
........................................................
−0.3V
to 6V
V
BST
to PGND ..................................................
−0.3V
to 35V
V
FB
, V
PG
to PGND .............................
−0.3V
to (VDD + 0.3V)
V
EN
to PGND .......................................
−0.3V
to (VIN +0.3V)
PGND to SGND............................................
−0.3V
to +0.3V
Junction Temperature .............................................. +150°C
Storage Temperature (T
S
) .........................
−65°C
to +150°C
Lead Temperature (soldering, 10sec) ........................ 260°C
(2)
ESD Rating ................................................. ESD Sensitive
Operating Ratings
(3)
Supply Voltage (PVIN, VIN) ............................ 4.5V to 19V
PVDD, VDD Supply Voltage (PVDD, VDD) ..... 4.5V to 5.5V
Enable Input (V
EN
) ................................................. 0V to VIN
Junction Temperature (T
J
) ........................
−40°C
to +125°C
Maximum Power Dissipation ...................................... Note 4
(4)
Package Thermal Resistance
5mm x 6mm QFN-28 (θ
JA
) ................................ 28°C/W
5mm x 6mm QFN-28 (θ
JC
) ............................... 2.5°C/W
Electrical Characteristics
(5)
PVIN = VIN = V
EN
= 12V, V
BST
– V
SW
= 5V; T
A
= 25°C, unless noted.
Bold
values indicate –40°C
≤
T
J
≤
+125°C.
Parameter
Power Supply Input
Input Voltage Range (VIN, PVIN)
Quiescent Supply Current
Shutdown Supply Current
VDD Supply Voltage
VDD Output Voltage
VDD UVLO Threshold
VDD UVLO Hysteresis
Dropout Voltage (VIN – VDD)
DC/DC Controller
Output-Voltage Adjust Range
(V
OUT
)
Reference
Feedback Reference Voltage
Load Regulation
Line Regulation
FB Bias Current
Notes:
1.
2.
3.
4.
5.
6.
7.
Exceeding the absolute maximum rating may damage the device.
Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5kΩ in series with 100pF.
The device is not guaranteed to function outside operating range.
PD
(MAX)
= (T
J(MAX)
– T
A
)/
θ
JA
, where
θ
JA
depends upon the printed circuit layout. A 5 square inch 4 layer, 0.62”, FR-4 PCB with 2oz finish copper
weight per layer is used for the
θ
JA
.
Specification for packaged product only.
Measured in test mode.
The maximum duty-cycle is limited by the fixed mandatory off-time t
OFF
of typically 300ns.
Condition
Min.
4.5
Typ.
Max.
19
Units
V
µA
µA
V
V
mV
mV
V
FB
= 1.5V (non-switching)
V
EN
= 0V
VIN = 7V to 19V, I
DD
= 40mA
VDD Rising
I
DD
= 25mA
4.8
3.7
450
5
5
4.2
400
380
750
10
5.4
4.5
600
0.8
5.5
V
0°C
≤
T
J
≤
85°C (±1.0%)
–40°C
≤
T
J
≤
125°C (±1.5%)
I
OUT
= 3A to 12A (Continuous Mode)
VIN = 4.5V to 19V
V
FB
= 0.8V
0.792
0.788
0.8
0.8
0.25
0.25
50
0.808
0.812
V
%
%
500
nA
December 2012
4
M9999-121012-A
Micrel, Inc.
MIC24056
Electrical Characteristics
(5)
(Continued)
PVIN = VIN = V
EN
= 12V, V
BST
– V
SW
= 5V; T
A
= 25°C, unless noted.
Bold
values indicate
−40°C ≤
T
J
≤ +125°C.
Parameter
Enable Control
EN Logic Level High
EN Logic Level Low
EN Bias Current
Oscillator
Switching Frequency
Maximum Duty Cycle
Minimum Duty Cycle
Minimum Off-Time
Soft-Start
Soft-Start time
Short-Circuit Protection
Current-Limit Threshold
Short-Circuit Current
Internal FETs
Top-MOSFET R
DS (ON)
Bottom-MOSFET R
DS (ON)
SW Leakage Current
V
IN
Leakage Current
Power Good
PG Threshold Voltage
PG Hysteresis
PG Delay Time
PG Low Voltage
Thermal Protection
Over-Temperature Shutdown
Over-Temperature Shutdown Hysteresis
T
J
Rising
160
15
°C
°C
Sweep V
FB
from Low to High
Sweep V
FB
from High to Low
Sweep V
FB
from Low to High
Sweep V
FB
<
0.9
×
V
NOM
, I
PG
= 1mA
85
92
5.5
100
70
200
95
%V
OUT
%V
OUT
µs
mV
I
SW
= 3A
I
SW
= 3A
V
EN
= 0V
V
EN
= 0V
13
5.3
60
25
mΩ
mΩ
µA
µA
V
FB
= 0.8V, T
J
= 25°C
V
FB
= 0.8V, T
J
= 125°C
V
FB
= 0V
18.75
17.36
21
12
38.5
38.5
A
A
3
ms
(6)
(7)
Condition
Min.
1.8
Typ.
Max.
Units
V
0.6
V
EN
= 12V
450
V
FB
= 0V
V
FB
= 1.0V
6
600
82
0
300
30
750
V
µA
kHz
%
%
ns
December 2012
5
M9999-121012-A
微控制器 MCU
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