MIC33050 Eval Board User Guide Datasheet by Microchip Technology

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MIC33050 Evaluation Board
4MHz Internal Inductor PWM Buck
Regulator with HyperLight Load®
HyperLight Load is a 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
March 24, 2014
1
Revision 4.0
General Description
The MIC33050 is a 600mA 4MHz switching regulator
featuring HyperLight Load® mode. The MIC33050 is
highly efficient throughout the entire output current
range, drawing just 20µA of quiescent current in
operation. The tiny 3mm x 3mm MLF® package, in
combination with the 4MHz switching frequency, enables
a compact sub-1mm height solution with only three
external components. The MIC33050 provides accurate
output voltage regulation under the most demanding
conditions and responds extremely quickly to a load
transient with exceptionally small output voltage ripple.
Factoring in the output current, the internal circuitry of
the MIC33050 automatically selects between two modes
of operation for optimum efficiency. Under light load
conditions, the MIC33050 goes into HyperLight Load
mode. HyperLight Load uses a pulse-frequency
modulation (PFM) control scheme that controls the off
time at light load. This proprietary architecture reduces
the amount of switching needed at light load, thereby
increasing operating efficiency. The MIC33050 attains
up to 83% efficiency at 1mA output load. As the load
current increases beyond approximately 100mA, the
device operates using the pulse-width modulation
(PWM) method for up to 93% efficiency at higher load.
The two modes of operation ensure the highest
efficiency across the entire load range.
The MIC33050 operates from an input voltage range of
2.7V to 5.5V and features internal power MOSFETs that
deliver up to 600mA of output current. This step-down
regulator provides an output voltage accuracy of ±2.5%
across the junction temperature range of 40ºC to
+125ºC. The MIC33050 is available in fixed or adjustable
versions supporting an output voltage as low as 0.7V.
Requirements
The MIC33050 evaluation board requires an input power
source that is able to deliver greater than 650mA at
2.7V. The output load can either be an active (electronic)
or passive (resistive) load.
Getting Started
1. Connect an external supply to the VIN (J1)
terminal. Apply the desired input voltage to VIN (J1)
and ground (J2) terminals of the evaluation board,
paying careful attention to polarity and supply
voltage (2.7V ≤ VIN ≤ 5.5V). An ammeter may be
placed between the input supply and the VIN (J1)
terminal. Be sure to monitor the supply voltage at
the VIN (J1) terminal, since the ammeter and/or
power lead resistance can reduce the voltage
supplied to the device.
2. Connect a load to the VOUT (J3) and ground
terminal (J4). The load can be either passive
(resistive) or active (electronic load). An ammeter
may be placed between the load and the output
terminal. Ensure the output voltage is monitored at
the VOUT (J3) terminal.
3. Enable the MIC33050. The MIC33050 evaluation
board has a pull-up resistor to VIN. To disable the
device, apply a voltage below 0.5V to the EN (J5)
terminal. In the absence of the pull-up resistor, the
device is enabled by applying a voltage greater than
1.2V to the EN (J5) terminal. The enable pin must be
either pulled high or low for proper operation.
Removing the pull-up resistor and leaving the pin
floating will cause the regulator to operate in an
unknown state.
Output Voltage
The MIC33050 evaluation board is available with the
following output voltage options listed in Ordering
Information.
Ordering Information
Part Number
MIC33050-CYHL EV
MIC33050-4YHL EV
MIC33050-GYHL EV
MIC33050-SYHL EV
MIC33050-AYHL EV
u1 MICHDSO-AYHL vm vow EN 5N5 sw ADJ PGND AGND
Micrel, Inc.
MIC33050 Evaluation Board
March 24, 2014
2
Revision 4.0
Output Voltage (Adjustable Option Only)
The output voltage of the MIC33050-AYHL is set by the
feedback resistors R2 and R3. Follow the equation and
circuit below to determine VOUT:
R3
R2
10.4VVOUT
Eq. 1
Figure 1. Typical Circuit for MIC33050-AYHL (VOUT = 1.8V)
The default output voltage for the evaluation board is set
to 1.8V (R2=348kΩ, R3=100kΩ). A different output
voltage can be obtained by removing R2 and replacing it
with the desired resistance. The equation below can be
used to find R2:
1
0.4V
V
R3R2 OUT
Eq. 2
Changing the output voltage to 2.5V, assuming
R3=100kΩ, can be accomplished via the equation
below:
1
0.4V
2.5V
100kΩR2
Eq. 3
The result is 523kΩ for R2 which gives an output voltage
of 2.5V.
HyperLight Load Mode
MIC33050 uses a minimum on and off time proprietary
control loop (patented by Micrel). 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.
This increases the output voltage. If the output voltage is
over the regulation threshold, then the error comparator
turns the PMOS off for a minimum-off-time until the
output drops below the threshold. 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, the MIC33050 works in pulse
frequency modulation (PFM) to regulate the output. As
the output current increases, the off-time decreases,
thus provides more energy to the output. This switching
scheme improves the efficiency of MIC33050 during light
load currents by only switching when it is needed. As the
load current increases, the MIC33050 goes into
continuous conduction mode (CCM) and switches at a
frequency centered at 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
IOUT
IN
LOAD
Eq. 4
As shown in the previous equation, the load at which
MIC33050 transitions from HyperLight Load mode to
PWM mode is a function of the input voltage (VIN), output
voltage (VOUT), duty cycle (D), inductance (L) and
frequency (f). As shown in Figure 1, as the Output
Current increases, the switching frequency also
increases until the MIC33050 goes from HyperLight
Load mode to PWM mode at approximately 120mA. The
MIC33050 will switch at a relatively constant frequency
around 4MHz once the output current is over 120mA.
0.001
0.01
0.1
1
10
110 100 1000 10000
SW FREQUENCY (MHz)
OUTPUT CURRENT (mA)
SW Frequency
vs Output Current
L = 4.7µH
VOUT = 1.8V
COUT = 4.7µF
VIN = 3.0V VIN = 3.6V
VIN = 4.2V
Figure 2. SW Frequency vs. Output Current
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Micrel, Inc.
MIC33050 Evaluation Board
March 24, 2014
3
Revision 4.0
MIC33050 Typical Circuit (Fixed)
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
560pF Ceramic Capacitor, 50V, NPO, Size 0603
1
R1
CRCW0603100KFKEA
Vishay(2)
100kΩ, 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.
m J1 EN U J5 C1 4.7uF— U1 MIC33050-AYHL R1 100kfl VIN VOUT EN SNS SW ADJ PGND AGND ._._ CZ -— 4.7pF GND GND J2 E: O www Idkxzom ww \shay cam, c: www.micrel.com.
Micrel, Inc.
MIC33050 Evaluation Board
March 24, 2014
4
Revision 4.0
MIC33050 Typical 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
120pF Ceramic Capacitor, 50V, NPO, Size 0603
1
R1, R3
CRCW0603100KFKEA
Vishay(2)
100kΩ, Tolerance 1%, Size 0603
2
R2
CRCW0603348KFKEA
Vishay
348kΩ, Tolerance 1%, Size 0603
1
U1
MIC33050-AYHL
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.
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Micrel, Inc.
MIC33050 Evaluation Board
March 24, 2014
5
Revision 4.0
PCB Layout Recommendations
Top Layer
Bottom Layer
hugJ/www micre\.com m
Micrel, Inc.
MIC33050 Evaluation Board
March 24, 2014
6
Revision 4.0
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