MIC33050
4MHz Internal Inductor PWM Buck
Regulator with HyperLight Load®
HyperLight Load is a registered trademark 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
May 2012 M9999-050312-C
General Description
The Micrel MIC33050 is a high-efficiency 600mA PWM
synchronous buck (step-down) regulator with internal
inductor featuring HyperLight Load, a patent-pending
switching scheme that offers best-in-class light load
efficiency and transient performance while providing very
small external components and low output ripple at all
loads.
The MIC33050 also has a very-low typical quiescent
current of 20µA and can achieve over 85% efficiency even
at 1mA.
In contrast to traditional light load schemes, the HyperLight
Load architecture does not trade off control speed to
obtain low standby currents and in doing so, the device
only needs a small output capacitor to absorb the load
transient as the powered device goes from light load to full
load.
At higher loads, the MIC33050 provides a constant
switching frequency of greater than 4MHz while providing
peak efficiencies greater than 93%.
The MIC33050 is available in fixed and adjustable output
voltages and comes in a 12-pin 3mm x 3mm MLF® with a
junction operating range of –40C to +125C.
Data sheets and support documentation can be found on
Micrel’s web site at: www.micrel.com.
Features
Input voltage: 2.7V to 5.5V
600mA output current
Fixed and adjustable output voltage options
No external inductor required
Ultra-fast transient response
20µA quiescent current
4MHz switching in PWM mode
Low output voltage ripple
>93% peak efficiency
>85% efficiency at 1mA
Micropower shutdown
12-pin 3mm x 3mm MLF®
–40C to +125C junction temperature range
Applications
Cellular phones
Digital cameras
Portable media players
Wireless LAN cards
WiFi, WiMax, and WiBro modules
USB-powered devices
____________________________________________________________________________________________________________
Typical Application
Micrel, Inc. MIC33050
May 2012 2 M9999-050312-C
Ordering Information
Part Number Voltage Temperature Range Package Lead Finish
MIC33050-CYHL 1.0V –40° to +125°C 12-Pin 3mm x 3mm MLF® Pb-Free
MIC33050-4YHL 1.2V –40° to +125°C 12-Pin 3mm x 3mm MLF® Pb-Free
MIC33050-GYHL 1.8V –40° to +125°C 12-Pin 3mm x 3mm MLF® Pb-Free
MIC33050-SYHL 3.3V –40° to +125°C 12-Pin 3mm x 3mm MLF® Pb-Free
MIC33050-AYHL ADJ –40° to +125°C 12-Pin 3mm x 3mm MLF® Pb-Free
Notes:
1. Other output voltage options available. Please contact Micrel for details.
2. MLF® is a green RoHS-compliant package. Lead finish is NiPdAu. Mold compound is Halogen Free.
Pin Configur ation
12-Pin 3mm x 3mm MLF® (HL) Fixed Output
Top View
12-Pin 3mm x 3mm MLF® (HL) Adjustable Output
Top View
Pin Description
Pin Number
(Fixed) Pin Number
(Adj) Pin Name Pin Function
1 1 VIN Supply Voltage (Input): Requires bypass capacitor-to-GND.
2 2 PGND Power Ground.
3, 4, 5, 6 3, 4, 5, 6 SW Switch (Output): Internal power MOSFET output switches.
7, 8 7, 8 OUT Output after the internal inductor.
9 9 EN
Enable (Input): Logic low will shut down the device, reducing the quiescent
current to less than 4µA. Do not leave floating.
10 10 SNS
Input to the error amplifier. Connect to the external resistor divider network to
see the output voltage. For fixed output voltages connect VOUT (internal resistor
network sets the output voltage).
11 – CFF Feed forward capacitor connected to out sense pin.
– 11 FB
Feedback voltage. Connect a resistor divider from output to ground to set the
output voltage.
12 12 AGND Analog ground.
EP EP ePad Exposed Heatsink Pad. Connect to power ground for best thermal performance.
Micrel, Inc. MIC33050
May 2012 3 M9999-050312-C
Absolute Maximum Ratings(1)
Supply Voltage (VIN).........................................................6V
Output Switch Voltage (VSW) ............................................6V
Output Switch Current (ISW)..............................................2A
Logic Input Voltage (VEN) .................................. –0.3V to VIN
Storage Temperature Range (Ts)..............–65°C to +150°C
ESD Rating(3)................................................. ESD Sensitive
Operating Ratings(2)
Supply Voltage (VIN)......................................... 2.7V to 5.5V
Logic Input Voltage (VEN)…………………………-0.3V to VIN
Junction Temperature (TJ) ..................–40°C TJ +125°C
Thermal Resistance
3mm x 3mm MLF®-12 (JA)................................60°C/W
Electrical Characteristics(4)
TA = 25°C with VIN = VEN = 3.6V; CFF = 560pF; COUT = 4.7µF; IOUT = 20mA unless otherwise specified.
Bold values indicate –40°C< TJ < +125°C.
Parameter Condition Min. Typ. Max. Units
Supply Voltage Range 2.7 5.5 V
Undervoltage Lockout Threshold (turn-on) 2.45 2.55 2.65 V
UVLO Hysteresis 100 mV
Quiescent Current, Hyper LL mode IOUT = 0mA ; VSNS > 1.2*VOUT nominal 20 32 µA
Shutdown Current VIN = 5.5V; VEN = 0V 0.01 4 µA
Output Voltage Accuracy VIN = 3.0V; ILOAD = 20mA –2.5 +2.5 %
Current Limit in PWM Mode SNS = 0.9*VNOM 0.65 1 1.7 A
Output Voltage Line Regulation VIN = 3.0V to 5.5V; ILOAD = 20mA 0.5 %/V
Output Voltage Load Regulation 20mA < ILOAD < 500mA, 0.3 %
Feedback Voltage VIN = 3.0V; IOUT = 20mA 390 400 410 mV
Maximum Duty Cycle SNS VNOM 80 89 %
PWM Switch ON-Resistance ISW = 100mA PMOS
ISW = -100mA NMOS 0.45
0.5
Frequency ILOAD = 120mA 4 MHz
Soft-Start Time VOUT = 90% 650 µs
Enable Threshold (turn-on) 0.5 0.8 1.2 V
Enable Hysteresis 35 mV
Enable Input Current 0.1 2 µA
Over-temperature Shutdown 165 C
Over-temperature Shutdown
Hysteresis 20
C
Notes:
1. Exceeding the absolute maximum rating may damage the device.
2. The device is not guaranteed to function outside its operating rating.
3. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF.
4. Specification for packaged product only.
Micrel, Inc. MIC33050
May 2012 4 M9999-050312-C
Typical Characteristics
50
60
70
80
90
100
1 10 100 1000
EFFICIENCY (%)
OUTPUT CURRENT (mA)
Efficiency VOUT = 3.3V
VIN = 5.0V
VIN = 4.2V
VIN = 5.5V
50
60
70
80
90
100
1 10 100 1000
EFFICIENCY (%)
OUTPUT CURRENT (mA)
Efficiency VOUT = 1.8V
VIN = 4.2V
VIN = 3.6V
VIN = 3.0V
50
60
70
80
90
100
1 10 100 1000
EFFICIENCY (%)
OUTPUT CURRENT (mA)
Efficiency VOUT = 1.2V
VIN = 2.7V
VIN = 3.6V VIN = 4.2V
50
60
70
80
90
100
1 10 100 1000
EFFICIENCY (%)
OUTPUT CURRENT (mA)
Efficiency VOUT = 1.0V
VIN = 2.7V
VIN = 3.6V
VIN = 4.2V
L = 1uH
Quiescent Current vs.
Temperature
0
10
20
30
40
-40 -20 0 20 40 60 80 100 120
TEM P ERATURE ( ° C)
Q UIESCENT CURRE NT (uA)
V
IN
= 3.6V
V
OUT
= 1.8V
Quiescent Current vs. Input
Voltage
0
5
10
15
20
25
30
35
40
45
50
2.7 3.2 3.7 4.2 4.7 5.2
I NPUT VO LTAGE ( V)
Q UIESCENT CURRENT (µA)
V
IN
= 3.6V
V
OUT
= 1.8V
No Load
Switching Frequency vs.
Temperature
2.5
3
3.5
4
4.5
5
5.5
-40 -20 0 20 40 60 80 100 120
TEM P ERATURE ( ° C)
S WITCHING FREQ UENCY (MHz)
V
IN
= 3.6V
V
OUT
= 1.8V
Load = 150mA
Switching Frequency vs. Input
Voltage
2.50
3.00
3.50
4.00
4.50
5.00
5.50
2.70 3.20 3.70 4.20 4.70 5.20
I NPUT VOLTAGE ( V)
SWITCHING FREQUENCY (MHz)
V
IN
= 3.6V
V
OUT
= 1.8V
Load = 150mA
Feedback Voltage vs.
Temperature
0.3
0.32
0.34
0.36
0.38
0.4
0.42
0.44
0.46
0.48
0.5
-40 -20 0 20 40 60 80 100 120
TEMPERA TURE (° C)
FEEDBACK VOLTAGE (V )
V
IN
= 3.6V
V
OUT
= 1.8V
No Load
Micrel, Inc. MIC33050
May 2012 5 M9999-050312-C
Typical Characteristics (Continued)
Output Voltage vs . Temperature
1.7
1.75
1.8
1.85
1.9
-40 -20 0 20 40 60 80 100 120
TEMPERA TURE (°C)
O UTPUT VOLTAG E (V)
V
IN
= 3.6V
V
OUT
= 1.8V
No Load
Output Voltage vs. Input
Voltage (V)
1.7
1.75
1.8
1.85
1.9
2.7 3.2 3.7 4.2 4.7 5.2
INPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
Load = 20mA
1.70
1.75
1.80
1.85
1.90
0 100 200 300 400 500 600
OUTPUT CURRENT (mA)
Output Voltage
vs. Output Current
VIN = 3.6V
Micrel, Inc. MIC33050
May 2012 6 M9999-050312-C
Functional Characteristics
Micrel, Inc. MIC33050
May 2012 7 M9999-050312-C
Functional Characteristics (Continued)
Micrel, Inc. MIC33050
May 2012 8 M9999-050312-C
Functional Diagram
MIC33050 Fixed Output Block Diagram
MIC33050 Adjustable Output Block Diagram
Micrel, Inc. MIC33050
May 2012 9 M9999-050312-C
Functional Description
VIN
VIN provides power to the MOSFETs for the switch mode
regulator section and to the analog supply circuitry. Due to
the high switching speeds, it is recommended that a 2.2µF
or greater capacitor be placed close to VIN and the power
ground (PGND) pin for bypassing. Refer to the PCB
Layout Recommendations for details.
EN
The enable pin, EN, controls the on and off state of the
device. A high logic on the enable pin activates the
regulator while a low logic deactivates it. MIC33050
features built-in soft-start circuitry that reduces in-rush
current and prevents the output voltage from overshooting
at start-up. Do not leave floating.
SW
The pins at the switch node, SW, connect directly to the
internal inductor which provides the switching current
necessary to operate in PWM mode. Due to the high-
speed switching on this pin, the switch node should be
routed away from sensitive nodes such as the CFF and FB
pins.
OUT
The OUT pin is for the output voltage following the internal
inductor of the device. Connect an output filter capacitor
equal to 2.2µF or greater to this pin.
SNS
The sense pin, SNS, is needed to sense the output voltage
at the output filter capacitor. In order for the control loop to
monitor the output voltage accurately it is good practice to
sense the output voltage at the positive side of the output
filter capacitor where voltage ripple is smallest.
CFF
The CFF pin is connected to the SNS pin of MIC33050
with a feed-forward capacitor of 560pF. The CFF pin itself
is compared with the internal reference voltage (VREF) of
the device and provides the control path to control the
output. VREF is equal to 400mV. The CFF pin is sensitive to
noise and should be place away from the SW pin. Refer to
the layout recommendations for details.
FB
The feedback pin is provided for the adjustable output
version. An external resistor divider network is connected
from the output and is compared to the internal 400mV
internal reference voltage within the control loop.
The output voltage, of the circuit below, may be calculated
via the following equation:
2
1
14.0 R
R
VVOUT
PGND
Power ground (PGND) is the ground path for high current.
The current loop for the power ground should be as small
as possible and separate from the analog ground (AGND)
loop. Refer to the PCB Layout Recommendations for more
details.
AGND
Signal ground (AGND) is the ground path for the biasing
and control circuitry. The current loop for the signal ground
should be separate from the PGND loop. Refer to the PCB
Layout Recommendations for more details.
Micrel, Inc. MIC33050
May 2012 10 M9999-050312-C
Applications Information
Input Capacitor
A minimum of 2.2µF ceramic capacitor should be placed
close to the VIN pin and PGND pin for bypassing. X5R or
X7R dielectrics are recommended for the input capacitor.
Y5V dielectrics, aside from losing most of their
capacitance over temperature, they also become resistive
at high frequencies. This reduces their ability to filter out
high frequency noise.
Output Capacitor
The MIC33050 was designed for use with a 2.2µF or
greater ceramic output capacitor. A low equivalent series
resistance (ESR) ceramic output capacitor either X7R or
X5R is recommended. Y5V and Z5U dielectric capacitors,
aside from the undesirable effect of their wide variation in
capacitance over temperature, become resistive at high
frequencies.
Compensation
The MIC33050 is designed to be stable with an internal
inductor with a minimum of 2.2µF ceramic (X5R) output
capacitor.
Efficiency Considerations
Efficiency is defined as the amount of useful output power,
divided by the amount of power supplied.
100
IV IV
(%) Efficiency
ININ
OUTOUT
Maintaining high efficiency serves two purposes. It
reduces power dissipation in the power supply, reducing
the need for heat sinks and thermal design considerations
and it reduces consumption of current for battery powered
applications. Reduced current draw from a battery
increases the devices operating time and is critical in hand
held devices.
There are two types of losses in switching converters; DC
losses and switching losses. DC losses are simply the
power dissipation of I2R. Power is dissipated in the high
side switch during the on cycle. Power loss is equal to the
high side MOSFET RDSON multiplied by the square of the
Switch Current. During the off cycle, the low side N-
channel MOSFET conducts, also dissipating power.
Device operating current also reduces efficiency. The
product of the quiescent (operating) current and the supply
voltage is another DC loss. The current required driving
the gates on and off at a constant 4MHz frequency and the
switching transitions make up the switching losses.
50
60
70
80
90
100
1 10 100 1000
EFFICIENCY (%)
OUTPUT CURRENT (mA)
Efficiency VOUT = 1.8V
VIN = 4.2V
VIN = 3.6V
VIN = 3.0V
The Figure above shows an efficiency curve. From 1µA to
100mA, efficiency losses are dominated by quiescent
current losses, gate drive and transition losses. By using
the HyperLight Load® mode, the MIC33050 is able to
maintain high efficiency at low output currents.
Over 100mA, efficiency loss is dominated by MOSFET
RDSON and inductor losses. Higher input supply voltages
will increase the Gate-to-Source threshold on the internal
MOSFETs, thereby reducing the internal RDSON. This
improves efficiency by reducing DC losses in the device.
All but the inductor losses are inherent to the device. In
which case, inductor selection becomes increasingly
critical in efficiency calculations. As the inductors are
reduced in size, the DC resistance (DCR) can become
quite significant. The DCR losses can be calculated as
follows:
L
PD = IOUT
2 × DCR
From that, the loss in efficiency due to inductor resistance
can be calculated as follows;
100
LIV IV
1(%) Loss Efficiency
PDOUTOUT
OUTOUT
Efficiency loss due to DCR is minimal at light loads and
gains significance as the load is increased. Inductor
selection becomes a trade-off between efficiency and size
in this case.
Micrel, Inc. MIC33050
May 2012 11 M9999-050312-C
HyperLight Load Mode
The MIC33050 uses a minimum on and off time
proprietary control loop. When the output voltage falls
below the regulation threshold, the error comparator
begins a switching cycle that turns the PMOS on and
keeps it on for the duration of the minimum-on-time. When
the output voltage is over the regulation threshold, the
error comparator turns the PMOS off for a minimum-off-
time. The NMOS acts as an ideal rectifier that conducts
when the PMOS is off. Using a NMOS switch instead of a
diode allows for lower voltage drop across the switching
device when it is on. The asynchronous switching
combination between the PMOS and the NMOS allows the
control loop to work in discontinuous mode for light load
operations. In discontinuous mode, MIC33050 works in
pulse frequency modulation (PFM) to regulate the output.
As the output current increases, the switching frequency
increases. This improves the efficiency of the MIC33050
during light load currents. As the load current increases,
the MIC33050 goes into continuous conduction mode
(CCM) at a constant frequency of 4MHz. The equation to
calculate the load when the MIC33050 goes into
continuous conduction mode may be approximated by the
following formula:
f2L
D)V(V
IOUTIN
LOAD
Micrel, Inc. MIC33050
May 2012 12 M9999-050312-C
MIC33050 Typical Application Circuit (Fixed Output)
Bill of Materials
Item Part Number Manufacturer Description Qty
C1, C2 C1608X5R0J475K TDK(1) 4.7µF Ceramic Capacitor, 6.3V, X5R, Size 0603 2
C3 C1608C0G1H561J TDK(1) 560pF Ceramic Capacitor, 50V, NPO, Size 0603 1
R1 CRCW0603100KFKEA Vishay(2) 100k, Tolerance 1%, Size 0603 1
U1 MIC33050-xYHL Micrel, Inc. (3) 4MHz Internal Inductor PWM Buck Regulator with
HyperLight Load® Mode 1
Notes:
1. TDK: www.tdk.com.
2. Vishay: www.vishay.com.
3. Micrel, Inc: www.micrel.com.
Micrel, Inc. MIC33050
May 2012 13 M9999-050312-C
MIC33050 Typical Application Circuit (Adjustable)
Bill of Materials
Item Part Number Manufacturer Description Qty
C1, C2 C1608X5R0J475K TDK(1) 4.7µF Ceramic Capacitor, 6.3V, X5R, Size 0603 2
C3 C1608C0G1H121J TDK(1) 120pF Ceramic Capacitor, 50V, NPO, Size 0603 1
R1, R3 CRCW0603100KFKEA Vishay(2) 100k, Tolerance 1%, Size 0603 2
R2 CRCW0603348KFKEA Vishay(2) 348k, Tolerance 1%, Size 0603 1
U1 MIC33050-AYHL Micrel, Inc. (3) 4MHz Internal Inductor PWM Buck Regulator with
HyperLight Load® 1
Notes:
1. TDK: www.tdk.com
2. Vishay: www.vishay.com
3. Micrel, Inc: www.micrel.com
Micrel, Inc. MIC33050
May 2012 14 M9999-050312-C
PCB Layout Recommendations (Fixed)
Top Layer
Bottom Layer
Micrel, Inc. MIC33050
May 2012 15 M9999-050312-C
PCB Layout Recommendations (Adjustable)
Top Layer
Bottom Layer
Micrel, Inc. MIC33050
May 2012 16 M9999-050312-C
Package Information
12-Pin 3mm x 3mm MLF® (ML)
MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com
The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its
use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer.
Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product
can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant
into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A
Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk and Purchaser agrees to fully
indemnify Micrel for any damages resulting from such use or sale.
© 2007 Micrel, Incorporated.
