Micrel MIC23031-4YMT EV, MIC23031-CYMT EV, MIC23031-FYMT EV, MIC23031-AYMT EV, MIC23031 Getting Started

MIC23031 Evaluation Board

4MHz PWM 400mA Buck Regulator

with HyperLight Load®

General Description

The MIC23031 is a 400mA 4MHz switching regulator
featuring HyperLight Load
highly-efficient throughout the entire output current range,
drawing just 21µA of quiescent current in operation. The
tiny 1.6mm  1.6mm Thin DFN package in combination
with the 4MHz switching frequency enables a compact
sub-1mm height solution with only three external
components. The MIC23031 provides accurate output
voltage regulation under the most demanding conditions
responding extremely quickly to a load transient with
exceptionally small output voltage ripple.

®

mode. The MIC23031 is

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  V

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

Factoring in the output current, the internal circuitry of the
MIC23031 automatically selects between two modes of
operation for optimum efficiency. Under light-load
conditions, the MIC23031 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 loads, thereby
increasing operating efficiency. The MIC23031 attains up
to 88% 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 loads. The two modes of
operation ensure the highest efficiency across the entire
load range.

The MIC23031 operates from an input voltage range of

2.7V to 5.5V and features internal power MOSFETs that
deliver up to 400mA of output current. This step-down
regulator provides an output voltage accuracy of 2.5%
across the junction temperature range of 40C to 125C.
The MIC23031 is available in fixed or adjustable versions

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 MIC23031.

The MIC23031 evaluation board has a pull-up resistor
to VIN. To disable the device, apply a voltage below

0.5V to the EN (J5) terminal or place a jumper on JP1
to ground EN. 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 EN pin must be
either pulled high or low for proper operation. Remove
the pull-up regulator to operate in an indeterminable
state.

Output Voltage

The MIC23031 evaluation board is available with the
output voltage options listed in the Ordering Information
table.

supporting an output voltage as low as 0.7V.
Datasheets and support documentation are available on

Micrel’s web site at: www.micrel.com.

Requirements

The MIC23031 evaluation board requires an input power
source that is able to deliver greater than 500mA at 2.7V
to the MIC23031. The output load can either be an active
(electronic) or passive (resistive) load.

Ordering Information

Part Number Description

MIC23031-AYMT EV Adjustable-Output Evaluation Board
MIC23031-CYMT EV 1.0V Fixed-Output Evaluation Board
MIC23031-4YMT EV 1.2V Fixed-Output Evaluation Board
MIC23031-FYMT EV 1.5V Fixed-Output Evaluation Board
MIC23031-GYMT EV 1.8V Fixed-Output Evaluation Board

Note: Other voltage options available upon request.

HyperLight Load is a registered trademark of Micrel, Inc.

Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel [phone] • fax + 1 [phone] • http://www.micrel.com

June 17, 2014

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MIC23031 Evaluation Board

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Output Voltage (Adjustable Option Only)

The output voltage of the MIC23031-AYMT regulator is
determined by feedback resistors R1 and R2 whose
values are calculated in Equation 1:

Eq. 1

The output on the evaluation board is by default set to

1.8V (R1 = 383kΩ, R2 = 200kΩ), but can easily be

modified by removing R1 and replacing it with the value
that yields the desired output voltage.

Eq. 2

For optimum transient response performance, R2 should
be in the range of 180kΩ to 220kΩ.

As shown in Equation 3, the load at which the MIC23031
transitions from HyperLight Load m ode to PW M mode is a
function of the input voltage (VIN ), output voltage (VO UT),
duty cycle (D), inductanc e (L), and frequency (f) ( F igur e 1).
Suitable inductors f or the MIC23 031 range fr om 0.47µH to

4.7µH. The device may be tailored to enter HyperLight

Load mode or PWM mode at a specific load current by
selecting the appropria te inductor. For exam ple, if a 4.7µH
inductor is selected in a 3.6VIN to 1.8VOUT application,
the MIC23031 will trans ition into PWM mode at a load of
approximately 5mA. If , under the same conditions, a 1µH
inductor is chosen, the MIC23031 will tra nsition into PW M
mode at approximately 70mA.

HyperLight Load

MIC23031 uses a patented minimum on and off time
control loop at light loads. When the output voltage falls
below the lower regu lation threshold, t he error com parator
begins a switching cycle that turns the PMOS on and
keeps it on for the d uration of the minimum on-t ime. This
increases the output voltage. Once the output voltage rises
to the higher regulation threshold, the error comparator
turns the PMOS off for a minim um off-time until the output
drops down to the lower t hreshold. The NMOS ac ts as an
ideal rectifier that cond ucts when th e PMOS is off . Using a
NMOS switch instead of a diode reduces power dissipation
as current is sourc ed from ground. I n discont inuous m ode,
the MIC23031 work s in PFM to re gulate th e output . As the
output current incre ases, the off -time decreases, therefore
more energy is delivered to the output. This switching
scheme improves the efficiency of the MIC23031 during
light load currents by activating the power FETs only as
needed. As the load current increases, the MIC23031
goes into continuous conduction mode (CCM) and
switches at a frequency centered at 4MHz. Equation 3
calculates the load where the MIC23031 goes into
continuous-conduction mode:

Eq. 3

Figure 1. MIC23031 SW Frequency vs. Output Current

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MIC23031 Evaluation Board

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MIC23031 Typical Application Circuit (Fixed)

Bill of Materials

Item Part Number Manufacturer Description Qty.

C1, C2 C1608X5R0J475K TDK
R1 CRCW06031003FT1 Vishay

LQM21PN1R0MC0D Murata
LQH32CN1R0M33 Murata
LQM31PN1R0M00 Murata

L1

LQM31PNR47M00 Murata
GLF251812T1R0M TDK
MIPF2520D1R5 FDK
EPL2010-102 Coilcraft

U1 MIC23031-xYMT Micrel, Inc.

Notes:

1. TDK: www.tdk.com

2. Vishay: www.vishay.com.

3. Murata: www.murata.com.

4. FDK: www.fdk.co.jp.

5. Coilcraft: www.coilcraft.com.

6. Micrel, Inc.: www.micrel.com.

.

4.7µF Ceramic Capacitor, 6.3V, X5R, Size 0603 2

(2)

100kΩ, 1%, Size 0603 1

(3)

1µH, 0.8A, 190mΩ, L2mm × W1.25mm × H0.5mm
1µH, 1A, 60mΩ, L3.2mm × W2.5mm × H2.0mm
1µH, 1.2A, 120mΩ, L3.2mm × W1.6mm × H0.85mm

0.47µH, 1.4A, 80mΩ, L3.2mm × W1.8mm × H0.85mm
1µH, 0.8A, 100mΩ, L2.5mm × W1.8mm × H1.2mm

(4)

(5)

1.5µH, 1.5A, 70mΩ, L2.5mm × W2mm × H1mm
1µH, 1A, 86mΩ, L2mm × W1.8mm × H1mm

4MHz PWM 400mA Buck Regulator with HyperLight Load 1

1

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MIC23031 Evaluation Board

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MIC23031 Typical Application Circuit (Adjustable 1.8V)

Bill of Materials

Item Part Number Manufacturer Description Qty.

C1, C2 C1608X5R0J475K TDK
C3 Open
R1 CRCW06033833FT1 Vishay
R2 CRCW06032003FT1 Vishay 200kΩ, 1%, Size 0603 1
R3 CRCW06031003FT1 Vishay 100kΩ, 1%, Size 0603 1

LQM21PN1R0MC0D Murata
LQH32CN1R0M33 Murata
LQM31PN1R0M00 Murata

L1

LQM31PNR47M00 Murata
GLF251812T1R0M TDK
MIPF2520D1R5 FDK
EPL2010-102 Coilcraft

U1 MIC23031-AYMT Micrel, Inc.

Notes:

7. TDK: www.tdk.com

8. Vishay: www.vishay.com.

9. Murata: www.murata.com.

10. FDK: www.fdk.co.jp.

11. Coilcraft: www.coilcraft.com.

12. Micrel, Inc.: www.micrel.com.

.

4.7µF Ceramic Capacitor, 6.3V, X5R, Size 0603 2

(8)

383kΩ, 1%, Size 0603 1

(9)

1µH, 0.8A, 190mΩ, L2mm × W1.25mm × H0.5mm
1µH, 1A, 60mΩ, L3.2mm × W2.5mm × H2.0mm
1µH, 1.2A, 120mΩ, L3.2mm × W1.6mm × H0.85mm

0.47µH, 1.4A, 80mΩ, L3.2mm × W1.8mm × H0.85mm
1µH, 0.8A, 100mΩ, L2.5mm × W1.8mm × H1.2mm

(11)

1.5µH, 1.5A, 70mΩ, L2.5mm × W2mm × H1mm
1µH, 1A, 86mΩ, L2mm × W1.8mm × H1mm

4MHz PWM 400mA Buck Regulator with HyperLight Load 1

1

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MIC23031 Evaluation Board

PCB Layout Recommendations

Top Layer (Fixed)

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Bottom Layer (Fixed)

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MIC23031 Evaluation Board

PCB Layout Recommendations (Continued)

Top Layer (Adjustable)

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Bottom Layer (Adjustable)

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Micrel, Inc.

MIC23031 Evaluation Board

Package Information and Recommended Landing Pattern

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Note:

13. Package information is correct as of the publication date. For updates and most current information, go to www.micrel.com

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6-Pin 1.6mm × 1.6mm Thin DFN (MM)

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Revision 2.0

Micrel, Inc.

MIC23031 Evaluation Board

MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA

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nd Purchaser agrees to fully

TEL [phone] FAX [phone] WEB http://www.micrel.com

Micrel makes no representations or warranties with respect to the accuracy or completeness of the information furnished in this data sheet. This

information is not intended as a warranty and Micrel does not assume responsibility for its use. Micrel reserves the right to change circuitry,

specifications and descriptions at any time without notice. No license, whether express, implied, arisi ng by estoppel or otherwise, t o any intellectual

property rights is granted by this document. Except as provided in Micrel’s terms and conditions of sale for such products, Micrel assumes no liability

whatsoever, and Micrel disclaims any express or implied warranty relating to the sale and/or use of Micrel products including liabil ity or warranties

relating to fitness for a particular purpose, merchantability, or infringem ent of any patent, copyright or other intel l ect ual property ri ght.

Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product

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indemnify Micrel for any damages resulting from such use or sale.

© 2008 Micrel, Incorporated.

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