MIC26601
28V, 6A Hyper Speed Control™
Synchronous DC/DC Buck Regulator
SuperSwitcher II™
General Description
The Micrel MIC26601 is a constant-frequency, synchronous
buck regulator featuring a unique adaptive on-time control
architecture. The MIC26601 operates over an input supply
range of 4.5V to 28V and provides a regulated output of up to
6A of output current. The output voltage is adjustable down to
0.8V with a guaranteed accuracy of ±1%, and the device
operates at a switching frequency of 600kHz.
Micrel’s Hyper Speed Control™ architecture allows for ultra-
fast transient response while reducing the output capacitance
and also makes (High V
IN
)/(Low V
OUT
) operation possible.
This adaptive t
ON
ripple control architecture combines the
advantages of fixed-frequency operation and fast transient
response in a single device.
The MIC26601 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, foldback current limit, “hiccup mode” short-
circuit protection and thermal shutdown. An open-drain
Power Good (PG) pin is provided.
All support documentation can be found on Micrel’s web
site at:
www.micrel.com.
Features
•
Hyper Speed Control™ architecture enables
-
High Delta V operation (V
IN
= 28V and V
OUT
= 0.8V)
-
Small output capacitance
4.5V to 28V voltage input
6A output current capability, up to 95% efficiency
Adjustable output from 0.8V to 5.5V
±1% feedback accuracy
Any Capacitor™ stable
-
zero-to-high ESR
600kHz switching frequency
No external compensation
Power Good (PG) output
Foldback current-limit and “hiccup mode” short-circuit
protection
Supports safe startup into a pre-biased load
–40°C to +125°C junction temperature range
28-pin 5mm
×
6mm MLF
®
package
•
•
•
•
•
•
•
•
•
•
•
•
Applications
•
•
•
•
Distributed power systems
Communications/networking infrastructure
Set-top box, gateways, and routers
Printers, scanners, graphic cards, and video cards
_________________________________________________________________________________________________________________________
Typical Application
Efficiency (V
IN
= 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
1
2
3
4
5
6
7
8
OUTPUT CURRENT (A)
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
July 2011
M9999-071311-A
Micrel, Inc.
MIC26601
Ordering Information
Part Number
MIC26601YJL
Voltage
Adjustable
Switching Frequency
600kHz
Junction Temperature
Range
–40°C to +125°C
Package
28-Pin 5mm
×
6mm MLF
®
Lead
Finish
Pb-Free
Pin Configuration
28-Pin 5mm
×
6mm MLF
®
(YJL)
Pin Description
Pin Number
1
3
4, 9, 10,
11, 12
Pin Name
PVDD
NC
SW
Pin Function
5V Internal Linear Regulator (Output): PVDD supply is the power MOSFET gate drive supply voltage
and created by internal LDO from V
IN
. When V
IN
<
+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.
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.
Power Ground. PGND is the ground path for the MIC26601 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.
High-Side N-internal MOSFET Drain Connection (Input): The PV
IN
operating voltage range is from
4.5V to 28V. Input capacitors between the PVIN pins and the Power Ground (PGND) are required and
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
PGND
13,14,15,
16,17,18,19
PVIN
20
BST
July 2011
2
M9999-071311-A
Micrel, Inc.
MIC26601
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 open.
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 V
IN
. When V
IN
<
+5.5V, VDD
should be tied to PVIN pins. A 1.0µF ceramic capacitor from the VDD pin to PGND pins must be place
next to the IC.
23
24
25
26
27
28
SGND
FB
PG
EN
VIN
VDD
July 2011
3
M9999-071311-A
Micrel, Inc.
MIC26601
Absolute Maximum Ratings
(1, 2)
PV
IN
to PGND................................................
−0.3V
to +29V
V
IN
to PGND ....................................................−0.3V to PV
IN
PV
DD
, V
DD
to PGND .........................................
−0.3V
to +6V
V
SW
, V
CS
to PGND ..............................
−0.3V
to (PV
IN
+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 (V
DD
+ 0.3V)
V
EN
to PGND ........................................
−0.3V
to (V
IN
+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
Operating Ratings
(3)
Supply Voltage (PV
IN
, V
IN
) .................................4.5V to 28V
PVDD, VDD Supply Voltage (PV
DD
, V
DD
)..........4.5V to 5.5V
Enable Input (V
EN
).................................................. 0V to V
IN
Junction Temperature (T
J
) ........................
−40°C
to +125°C
Maximum Power Dissipation ..................................... Note 4
Package Thermal Resistance
(4)
5mm x 6mm MLF
®
(θ
JA
) ..................................... 28°C/W
Electrical Characteristics
(5)
PV
IN
= V
IN
= 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 (V
IN
, PV
IN
)
Quiescent Supply Current
Shutdown Supply Current
V
DD
Supply Voltage
V
DD
Output Voltage
V
DD
UVLO Threshold
V
DD
UVLO Hysteresis
Dropout Voltage (V
IN
– V
DD
)
DC/DC Controller
Output-Voltage Adjust Range (V
OUT
)
Reference
0°C
≤
T
J
≤
85°C (±1.0%)
−40°C ≤
T
J
≤
125°C (±1.5%)
Load Regulation
Line Regulation
FB Bias Current
Enable Control
EN Logic Level High
EN Logic Level Low
EN Bias Current
Oscillator
Switching Frequency
(6)
Maximum Duty Cycle
Minimum Duty Cycle
Minimum Off-Time
(7)
Condition
Min.
Typ.
Max.
Units
4.5
V
FB
= 1.5V (non-switching)
V
EN
= 0V
V
IN
= 7V to 28V, I
DD
= 40mA
V
DD
Rising
I
DD
= 25mA
0.8
0.792
0.788
0.8
0.8
0.25
0.25
50
1.8
4.8
3.7
730
5
5
4.2
400
380
28
1500
10
5.4
4.5
600
5.5
0.808
0.812
V
µA
µA
V
V
mV
mV
V
V
%
%
nA
V
I
OUT
= 0A to 6A (continuous mode)
V
IN
= 4.5V to 28V
V
FB
= 0.8V
0.6
V
EN
= 12V
V
FB
= 0V
V
FB
= 1.0V
450
6
600
82
0
300
30
750
V
µA
kHz
%
%
ns
July 2011
4
M9999-071311-A
Micrel, Inc.
MIC26601
Electrical Characteristics
(5)
(Continued)
PV
IN
= V
IN
= V
EN
= 12V, V
BST
– V
SW
= 5V; T
A
= 25°C, unless noted.
Bold
values indicate
−40°C ≤
T
J
≤
+125°C.
Parameter
Soft-Start
Soft-Start Time
Short-Circuit Protection
Current-Limit Threshold
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)
PG Threshold Voltage
PG Hysteresis
PG Delay Time
PG Low Voltage
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. 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
.
5. Specification for packaged product only.
6. Measured in test mode.
7. The maximum duty-cycle is limited by the fixed mandatory off-time t
OFF
of typically 300ns.
Condition
Min.
Typ.
5
Max.
Units
ms
V
FB
= 0.8V, T
J
= 25°C
V
FB
= 0.8V, T
J
= 125°C
V
FB
= 0V
I
SW
= 1A
I
SW
= 1A
V
EN
= 0V
V
EN
= 0V
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
T
J
Rising
7.5
6.6
13
13
2.7
42
12.5
17
17
A
A
A
mΩ
mΩ
60
25
85
92
5.5
100
70
160
15
200
95
µA
µA
%V
OUT
%V
OUT
µs
mV
°C
°C
July 2011
5
M9999-071311-A
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