mps MPM3810 Synchronous Step-Down Converter with Integrated Inductor
Product Information
The MPM3810 is a 6V input, 1.2A module synchronous step-down converter with an integrated inductor. It is designed for a wide range of applications including high-performance DSPs, FPGAs, PDAs, portable instruments, and storage. The product is lead-free and adheres to the RoHS directive. The MPM3810 is a registered trademark of Monolithic Power Systems, Inc.
Product Usage Instructions
To use the MPM3810, follow the steps below:
- Select the appropriate part number based on your desired output voltage:
- MPM3810GQB* – Vo Range Adjustable
- MPM3810GQB-12 – Fixed 1.2V
- MPM3810GQB-18 – Fixed 1.8V
- MPM3810GQB-25 – Fixed 2.5V
- MPM3810GQB-33 – Fixed 3.3V
- Refer to the package reference for the specific part number QFN-12 (2.5mmX3.0mmX0.9mm)
- Ensure that the supply voltage (VIN) does not exceed 6.5V and that the VSW voltage remains within the specified range (-0.3V).
Note: Unauthorized photocopying and duplication of the product in the manual is prohibited.
DESCRIPTION
The MPM3810 is a step-down module converter with built-in power MOSFETs and an inductor. The module’s integrated inductor simplifies the power system design and provides easy, efficient use. The DC-DC module comes in a small surface-mount QFN-12 (2.5mmx3.0mmx0.9mm) package and achieves 1.2A peak output current from a 2.5V to 6V input voltage with excellent load and line regulation. The output voltage is regulated as low as 0.6V. For adjustable output, only FB resistors and input and output capacitors are needed to complete the design. The constant-on-time control (COT) scheme provides fast, transient response and eases loop stabilization. Fault condition protection includes a cycle-by-cycle current limiting and thermal shutdown (TSD). The MPM3810 is ideal for a wide range of applications including high-performance DSPs, FPGAs, PDAs, portable instruments, and storage.
FEATURES
- • Wide 2.5V to 6V Operating Input Range
• Fixed and Adjustable Output from 0.6V
• QFN-12 (2.5mmx3.0mmx0.9mm) Package
• Total Solution Size 6mm x 3.8mm
• Up to 1.2A Peak Output Current
• 100% Duty Cycle in Dropout
• Ultra Low IQ: 17μA
• EN and Power Good for Power Sequencing
• Cycle-by-Cycle Over-Current Protection
• Short-Circuit Protection with Hiccup Mode
• Adjustable Output Only Needs 4 External Components: 2 Ceramic CapacitorAs and FB Divider Resistors
• Fixed Output Only Needs Input and Output Capacitors
APPLICATIONS
• Low Voltage I/O System Power
• LDO Replacement
• Power for Portable Products
• Storage (SSD/HDD)
• Space-Limited Applications
All MPS parts are lead-free and adhere to the RoHS directive. For MPS green
status, please visit MPS website under the Products, Quality Assurance page.
“MPS” and “The Future of Analog IC Technology” are Registered Trademarks of
Monolithic Power Systems, Inc.
TYPICAL APPLICATION (Fixed Output)
ORDERING INFORMATION
For Tape & Reel, add suffix –Z (e.g. MPM3810GQB–Z);
PACKAGE REFERENCE
ABSOLUTE MAXIMUM RATINGS (1)
- Supply Voltage VIN ……………………………….. 6.5V
VSW …………………………………………………………..
-0.3V (-5V for <10ns) to 6.5V (7V for <10ns)
All Other Pins …………………………. -0.3V to 6.5 V
Junction Temperature ………………………… 150°C
Lead Temperature …………………………….. 260°C
Continuous Power Dissipation (TA = +25°C) (2)
……….….. …………………………………………. 1.9W
Storage Temperature …………… -65°C to +150°C
Recommended Operating Conditions (3)
Supply Voltage VIN ………………………. 2.5V to 6V
Output Voltage VOUT ……………… 12% x VIN to VIN
Operating Junction Temp. (TJ). -40°C to +125°C
Thermal Resistance (4) θJA θJC
QFN-12 (2.5mmX3.0mm)……65 13 °C/W
Notes:
1) Exceeding these ratings may damage the device.
2) The maximum allowable power dissipation is a function of the
maximum junction temperature TJ (MAX), the junction-toambient
thermal resistance θJA, and the ambient temperature
TA. The maximum allowable continuous power dissipation at
any ambient temperature is calculated by PD (MAX) = (TJ
(MAX)-TA)/θJA. Exceeding the maximum allowable power
dissipation will cause excessive die temperature, and the
regulator will go into thermal shutdown. Internal thermal
shutdown circuitry protects the device from permanent
damage.
3) The device is not guaranteed to function outside of its
operating conditions.
4) Measured on JESD51-7, 4-layer PCB.
ELECTRICAL CHARACTERISTICS
VIN = 5V, TJ = -40°C to +125°C, Typical value is tested at TJ = +25°C. The limit over temperature is
guaranteed by characterization, unless otherwise noted.
ELECTRICAL CHARACTERISTICS (continued)
VIN = 5V, TJ = -40°C to +125°C, Typical value is tested at TJ = +25°C. The limit over temperature is
guaranteed by characterization, unless otherwise noted.
TYPICAL PERFORMANCE CHARACTERISTICS
VIN = 5V, VOUT = 1.2V, CIN=10μF, COUT=20μF, TA = +25ºC, unless otherwise noted.
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 5V, VOUT = 1.2V, CIN=10μF, COUT=20μF, TA = +25ºC, unless otherwise noted.
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 5V, VOUT = 1.2V, CIN=10μF, COUT=20μF, TA = +25ºC, unless otherwise noted.
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 5V, VOUT = 1.2V, CIN=10μF, COUT=20μF, TA = +25ºC, unless otherwise noted.
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 5V, VOUT = 1.2V, CIN=10μF, COUT=20μF, TA = +25ºC, unless otherwise noted.
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 5V, VOUT = 1.2V, CIN=10μF, COUT=20μF, TA = +25ºC, unless otherwise noted.
PIN FUNCTIONS
OPERATION
The DC-DC module has a small surface-mount
QFN-12 (2.5mmx3.0mmx0.9mm) package. The
module’s integrated inductor simplifies the
schematic and layout design. Only FB resistors
and input and output capacitors are needed to
complete the design. MPM3810 uses constant
on-time control (COT) with input voltage feed
forward to stabilize the switching frequency over
a full-input range. At light load, MPM3810
employs a proprietary control of the low-side
switch and inductor current to improve efficiency.
Constant On-Time Control (COT)
Compared to a fixed-frequency PWM control,
constant on-time control (COT) offers the
advantage of a simpler control loop and faster
transient response. Using input voltage feed
forward, the MPM3810 maintains a nearly constant
switching frequency across the input and output
voltage range. The on-time of the switching pulse
is estimated as follows:
OUT
ON
IN
T V 0.28us
V
= ⋅
To prevent inductor current run away during load
transition, MPM3810 fixes the minimum off time to
60ns. However, this minimum off-time limit does
not affect operation in a steady state.
Light-Load Operation
In a light-load condition, MPM3810 uses a
proprietary control scheme to save power and
improve efficiency. The MP3810 turns off the
low-side switch when the inductor current begins
to reverse. Then MP3810 works in discontinuous
conduction mode (DCM) operation.
A zero current cross circuit detects if the inductor
current begins to reverse. Considering the
internal circuit propagation time, the typical delay
time is 30ns. This means the inductor current
continues to fall after the ZCD is triggered. If the
inductor current falling slew rate is fast (Vo
voltage is high or close to Vin), the low-side
MOSFET turns off (this means the inductor
current may be negative). This does not allow the
MPM3810 to enter DCM. If DCM is required, the
off-time of the low-side MOSFET in continuous
conduction mode (CCM) should be longer than
60ns. For example, if Vin is 3.6V and Vo is 3.3V,
the off-time in CCM is 24ns. It is difficult to enter
DCM at light load.
Enable (EN)
If the input voltage is greater than the undervoltage
lockout threshold (UVLO), typically 2.3V,
MPM3810 is enabled by pulling EN above 1.2V.
Leaving EN to float or be pulled down to ground
disables MPM3810. There is an internal 1MΩ
resistor from EN to ground.
Soft-Start (SS)
MPM3810 has a built-in soft-start that ramps up
the output voltage in a controlled slew rate. This
avoids overshoot at startup. The soft-start time is
about 1.5ms typically.
Power GOOD Indictor (PGOOD)
MPM3810 has an open drain with a 550kΩ pullup
resistor pin for the power good indicator
(PGOOD). When FB is within +/-10% of
regulation voltage (i.e. 0.6V), PGOOD is pulled
up to IN by the internal resistor. If FB voltage is
out of the +/-10% window, PGOOD is pulled
down to ground by an internal MOSFET. The
MOSFET has a maximum Rdson of less than
400Ω.
Current Limit
MPM3810 has a typical 2.1A current limit for the
high-side switch. When the high-side switch
reaches the current limit, MPM3810 hits the
hiccup threshold until the current decreases. This
prevents the inductor current from continuing to
build, which results in damage to the components.
Short Circuit and Recovery
MPM3810 enters short-circuit protection (SCP)
mode when the current limit is reached; then it
tries to recover from the short circuit with hiccup
mode. In SCP, MPM3810 disables the output
power stage, discharges the soft-start cap and
then automatically tries to soft-start again. If the
short circuit remains after the soft-start ends,
MPM3810 repeats the cycle until the short circuit
disappears, and the output rises back to the
regulation level.
FUNCTIONAL BLOCK DIAGRAM
APPLICATION INFORMATION
COMPONENT SELECTION
Setting the Output Voltage
The external resistor divider is used to set the
output voltage (see Typical Application on page
16). The feedback resistor R1 cannot be too
large or too small considering the trade-off for
stability and dynamics. Choose R1 betwee
The feedback circuit is shown in Figure 2.
Table 1 lists the recommended resistor values for
common output voltages.
Table 1: Resistor Values for Common Output
Voltages
Selecting the Input Capacitor
The input current to the step-down converter is
discontinuous, therefore a capacitor is required to
supply the AC current while maintaining the DC
input voltage. For optimal performance, use low
ESR capacitors. Ceramic capacitors with X5R or
X7R dielectrics are highly recommended due to
their low ESR and small temperature coefficients.
For most applications, a 10μF capacitor is
sufficient.
For higher output voltage, a 22μF may be
needed to enhance system stability.
Since the input capacitor absorbs the input
switching current, it requires an adequate ripplecurrent
rating. The RMS current in the input
capacitor can be estimated by:
The worst case condition occurs at VIN = 2VOUT,
where:
For simplification, choose the input capacitor that
has a RMS current rating greater than half of the
maximum load current.
The input capacitor can be electrolytic, tantalum
or ceramic. When using electrolytic or tantalum
capacitors, a small, high quality ceramic
capacitor (i.e. 0.1μF), should be placed as close
to the IC as possible. When using ceramic
capacitors, check that they have enough
capacitance to provide sufficient charge to
prevent an excessive voltage ripple at input. The
input-voltage ripple caused by capacitance is
estimated by:
Selecting the Output Capacitor
The output capacitor (COUT) is required to
maintain the DC output voltage. Ceramic
capacitors are recommended. Low ESR
capacitors are preferred to keep the outputvoltage
ripple low. The output voltage ripple is
estimated by:
Where L1 is the inductor value, and RESR is the
equivalent series resistance (ESR) value of the
output capacitor (L1 is 0.47μH).
When using ceramic capacitors, the impedance
at the switching frequency is dominated by the
capacitance. The output-voltage ripple is mainly caused by the capacitance. For simplification, the
output-voltage ripple is estimated by:
When using tantalum or electrolytic capacitors,
the ESR dominates the impedance at the
switching frequency. For simplification, the output
ripple can be approximated by
The characteristics of the output capacitor affect
the stability of the regulation system.
PCB Layout
The module’s integrated inductor simplifies the
schematic and layout design (see Figures 3 and
4). Only FB resistors and input and output
capacitors are needed to complete the design.
The high-current paths (PGND, IN and OUT)
should be placed very close to the device with
short, direct, and wide traces. The input capacitor
needs to be as close to IN and PGND as
possible. The external feedback resistors should
be placed next to FB. Keep the switching node
away from the feedback network. For additional
device applications, please refer to related
evaluation board datasheets (EVB).
TYPICAL APPLICATION CIRCUITS (Adjustable Output)
PACKAGE INFORMATION
NOTICE: The information in this document is subject to change without notice. Please contact MPS for current specifications.
Users should warrant and guarantee that third party Intellectual Property rights are not infringed upon when integrating MPS
products into any application. MPS will not assume any legal responsibility for any said applications.
