Datasheet MP2105DJ Datasheet (MPS) [ru]

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MP2105

1MHz, 800mA Synchronous

Step-Down Converter

The Future of Analog IC Technology

DESCRIPTION

The MP2105 is a 1MHz constant frequency, current mode, PWM step-down converter. The device integrates a main switch and a synchronous rectifier for high efficiency without an external Schottky diode. It is ideal for powering portable equipment that runs from a single cell Lithium-Ion (Li+) battery. The MP2105 can supply 800mA of load current from a 2.5V to 6V input voltage. The output voltage can be regulated as low as 0.6V. The MP2105 can also run at 100% duty cycle for low dropout applications.

The MP2105 is available in a low profile (1mm) 5-pin, TSOT package.

EVALUATION BOARD REFERENCE

Board Number Dimensions

EV2105DJ-00A 2.0”X x 2.0”Y x 0.5”Z

FEATURES

• High Efficiency: Up to 95%

• 1MHz Constant Switching Frequency

• 800mA Available Load Current

• 2.5V to 6V Input Voltage Range

• Output Voltage as Low as 0.6V

• 100% Duty Cycle in Dropout

• Current Mode Control

• Short Circuit Protection

• Thermal Fault Protection

• <0.1µA Shutdown Current

• Space Saving 5-Pin TSOT23 Package

APPLICATIONS

• Cellular and Smart Phones

• Microprocessors and DSP Core Supplies

• PDAs

• MP3 Players

• Digital Still and Video Cameras

• Portable Instruments

TYPICAL APPLICATION

INPUT

2.5V to 6V

OFF ON

MP2105

GND

“MPS” and “The Future of Analog IC Technology” are Trademarks of Monolithic Power Systems, Inc.

Efficiency vs Load Current

100

= 3.3V

OUTPUT

1.8V 800mA

MP2105_TAC_S01

EFFICIENCY (%)

10 100 1000

= 4.2V

LOAD CURRENT (mA)

MP2105-EC01

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MP2105 – 1MHz 800mA SYNCHRONOUS STEP-DOWN CONVERTER

PACKAGE REFERENCE

TOP VIEW

C 6 YW

54FB

MP1557_PD01_TSOT23-5

–40°C to +85°C

GND

Part Number* Package Temperature

MP2105DJ TSOT23-5

For Tape & Reel, add suffix –Z (eg. MP2105DJ–Z)

For Lead Free, add suffix –LF (eg. MP2105DJ–LF–Z)

ABSOLUTE MAXIMUM RATINGS

(1)

VIN to GND .................................. –0.3V to +6.5V

to GND........................... –0.3V to VIN +0.3V

, VEN to GND.......................... –0.3V to +6.5V

Junction Temperature.............................+150°C

Lead Temperature ..................................+260°C

Storage Temperature .............–65°C to +150°C

Recommended Operating Conditions

(2)

Supply Voltage VIN............................. 2.5V to 6V

Output Voltage V

.......................... 0.6V to 6V

OUT

Operating Temperature .............–40°C to +85°C

Thermal Resistance

(3)

θJC

TSOT23-5.............................. 220 .... 110.. °C/W

Notes:

1) Exceeding these ratings may damage the device.

2) The device is not guaranteed to function outside of its operating conditions.

3) Measured on approximately 1” square of 1 oz copper.

ELECTRICAL CHARACTERISTICS

(4)

VIN = VEN = 3.6V, TA = +25°C, unless otherwise noted.

Parameter Symbol Condition Min Typ Max Units

Supply Current VEN = VIN, VFB = 0.65V 440 600 µA Shutdown Current VEN = 0V, VIN = 6V 0.10 1 µA IN Undervoltage Lockout

Threshold IN Undervoltage Lockout

Hysteresis

Regulated FB Voltage VFB

FB Input Bias Current VFB = 0.65V –50 0.5 +50 nA PFET On Resistance ISW = 100mA 0.42 Ω NFET On Resistance ISW = –100mA 0.26 Ω

SW Leakage Current

PFET Current Limit

Oscillator Frequency f Thermal Shutdown Trip

Threshold EN Trip Threshold –40°C ≤ TA ≤ +85°C 0.3 0.96 1.5 V EN Input Current VEN = 0V to 6V –1 +1 µA

Notes:

4) 100% production test at +25°C. Specifications over the temperature range are guaranteed by design and characterization.

Rising Edge 2.15 2.30 2.40 V

55 mV

TA = +25°C 0.588 0.600 0.612 –40°C ≤ T

= 0V, VIN = 6V,

= 0V or 6V

Duty Cycle = 100%, Current Pulse Width < 1ms

0.85 1.05 1.25 MHz

OSC

≤ +85°C 0.582 0.600 0.618

–1 +1 µA

1.2 1.6 2.1 A

145

°C

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MP2105 – 1MHz 800mA SYNCHRONOUS STEP-DOWN CONVERTER

TYPCIAL PERFORMANCE CHARACTERISTICS

VIN = 3.3V, V

= 1.8V, L1 = 4.7µH, C1 = 4.7µF, C3 = 10µF, TA = +25°C, unless otherwise noted.

OUT

100

VIN=3.3V

)

EFFICIENCY (

10 100 1000

VIN=4.2V

LOAD CURRENT (mA)

Feedback Voltage vs Temperature

0.603

0.602

0.601

0.600

0.599

0.598

FEEDBACK VOLTAGE (V)

0.597

-20

-40 +200 TEMPERATURE (°C)

+40 +60 +80 +100 -40 +200

MP2105-EC01

MP2105-TPC01

VIN=3.3V

)

EFFICIENCY (

10 100 1000

VIN=4.2V

LOAD CURRENT (mA)

Switching Frequency vs Temperature

1.10

1.08

1.06

1.04

1.02

1.00

0.98

0.96

SWITCHING FREQUENCY (MHz)

0.94

-20 TEMPERATURE (°C)

+40 +60 +80 +100

MP2105-EC02

MP2105-TPC02

Load Transient

=0mA to 500mA step)

OUT

100mV/div.

OUT

0.5A/div.

MP2105-TPC03

10mV/div.

0.2A/div.

2V/div.

Light Load Operation

=0mA)

OUT

MP2105-TPC04

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MP2105 – 1MHz 800mA SYNCHRONOUS STEP-DOWN CONVERTER

TYPCIAL PERFORMANCE CHARACTERISTICS (continued)

VIN = 3.3V, V

10mV/div.

0.2A/div.

= 1.8V, L1 = 4.7µH, C1 = 4.7µF, C3 = 10µF, TA = +25°C, unless otherwise noted.

OUT

Heavy Load Operation

OUT

= 800mA

OUT

2V/div.

1V/div.

Startup from Shutdown

OUT

2V/div.

OUT

1V/div.

0.5A/div.

Short Circuit Protection (No Load)

MP2105-TPC07

MP2105-TPC09

0.5A/div.

MP2105-TPC08

Short Circuit Recovery (No Load)

OUT

1V/div.

0.5A/div.

MP2105-TPC10

PIN FUNCTIONS

Pin # Name Description

EN 1

GND 2 Ground

SW 3 Power Switch Output. Inductor connection to drains of the internal PFET and NFET switches.

IN 4 Supply Input. Bypass to GND with a 2.2µF or greater ceramic capacitor.

FB 5

Regulator Enable Control Input. Drive EN above 1.5V to turn on the MP2105. Drive EN below

0.3V to turn it off (shutdown current < 0.1µA).

Feedback Input. Connect FB to the center point of the external resistor divider. The feedback threshold voltage is 0.6V.

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MP2105 – 1MHz 800mA SYNCHRONOUS STEP-DOWN CONVERTER

OPERATION

The MP2105 is a constant frequency current mode PWM step-down converter. The MP2105 is optimized for low voltage, Li-Ion battery powered applications where high efficiency and small size are critical. The MP2105 uses an external resistor divider to set the output voltage from 0.6V to 6V. The device integrates both a main switch and a synchronous rectifier, which provides high efficiency and eliminates

an external Schottky diode. The MP2105 can achieve 100% duty cycle. The duty cycle D of a step-down converter is defined as:

where T

OUT

OSCON

is the main switch on time, and f

%100fTD

%100

×≈××=

OSC

is the oscillator frequency (1MHz).

BIAS

VOLTAGE

REFERENCE

0.6V

FEEDBACK

ERROR\

AMP

EAMP

17pF

ICS

SLOPE COMP

EAO

Figure 1—Functional Block Diagram

PWMCMP

1.0MHz

OSCILLATOR

PWM

OSC

PWM

CONTROL

LOGIC

CURRENT

SENSE

AMP

IAMP

10X

MAIN SWITCH (PCH)

SYNCHRONOUS RECTIFIER (NCH)

GND

MP2105_BD01

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MP2105 – 1MHz 800mA SYNCHRONOUS STEP-DOWN CONVERTER

Current Mode PWM Control

Slope compensated current mode PWM control provides stable switching and cycle-by-cycle current limit for superior load and line response and protection of the internal main switch and synchronous rectifier. The MP2105 switches at a constant frequency (1MHz) and regulates the output voltage. During each cycle the PWM comparator modulates the power transferred to the load by changing the inductor peak current based on the feedback error voltage. During normal operation, the main switch is turned on for a certain time to ramp the inductor current at each rising edge of the internal oscillator, and switched off when the peak inductor current is above the error voltage. When the main switch is off, the synchronous rectifier will be turned on immediately and stay on until either the next cycle starts.

Dropout Operation

The MP2105 allows the main switch to remain on for more than one switching cycle and increases the duty cycle while the input voltage is dropping close to the output voltage. When the duty cycle reaches 100%, the main switch is held on continuously to deliver current to the output up to

the PFET current limit. The output voltage then is the input voltage minus the voltage drop across the main switch and the inductor.

Short Circuit Protection

The MP2105 has short circuit protection. When the output is shorted to ground, the oscillator frequency is reduced to prevent the inductor current from increasing beyond the PFET current limit. The PFET current limit is also reduced to lower the short circuit current. The frequency and current limit will return to the normal values once the short circuit condition is removed and the feedback voltage reaches 0.6V.

Maximum Load Current

The MP2105 can operate down to 2.5V input voltage; however the maximum load current decreases at lower input due to large IR drop on the main switch and synchronous rectifier. The slope compensation signal reduces the peak inductor current as a function of the duty cycle to prevent sub-harmonic oscillations at duty cycles greater than 50%. Conversely the current limit increases as the duty cycle decreases.

APPLICATION INFORMATION

Output Voltage Setting

The external resistor divider sets the output voltage (see Figure 3). The feedback resistor R1 also sets the feedback loop bandwidth with the internal compensation capacitor (see Figure 1).

Choose R1 around 500kΩ for optimal transient response. R2 is then given by:

Table 1—Resistor Selection vs. Output

Voltage Setting

R1 R2

OUT

1.2V

1.5V

1.8V

2.5V

499k

OUT

−

V6.0

Ω (1%) 499kΩ (1%)

Ω (1%) 332kΩ (1%)

Ω (1%) 249kΩ (1%)

Ω (1%) 158kΩ (1%)

Inductor Selection

A 1µH to 10µH inductor with DC current rating at least 25% higher than the maximum load current is recommended for most applications. For best efficiency, the inductor DC resistance shall be <200mΩ. See Table 2 for recommended inductors and manufacturers. For most designs, the inductance value can be derived from the following equation:

()

VVV

−×

OUTINOUT

OSCLIN

where ∆I

is Inductor Ripple Current. Choose inductor

fIV

×∆×

ripple current approximately 30% of the maximum load current, 800mA.

The maximum inductor peak current is:

∆

LOAD)MAX(L

Under light load conditions below 100mA, larger inductance is recommended for improved efficiency. Table 3 lists inductors recommended for this purpose.

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MP2105 – 1MHz 800mA SYNCHRONOUS STEP-DOWN CONVERTER

Table 2—Suggested Surface Mount Inductors

Saturation

Manufacturer Part Number Inductance (µH) Max DCR (Ω)

Coilcraft D01605T-472 4.7 0.150 1.20 5.4x4.2x1.8

Toko D52LC 4.7 0.087 1.14 5x5x2

Sumida CR43-4R7 4.7 0.109 1.15 4.3x4.8x3.5

Current (A)

Dimensions

LxWxH (mm3)

Table 3—Inductors for Improved Efficiency at 25mA, 50mA, under 100mA Load.

Saturation

Manufacturer Part Number Inductance (µH) Max DCR (Ω)

Coilcraft DO1605T-103MX 10 0.3 1.0 0.9

Murata LQH4C100K04 10 0.2 1.2 0.8 Sumida CR32-100 10 0.2 1.0 0.7 Sumida CR54-100 10 0.1 1.2 1.4

Input Capacitor Selection

The input capacitor reduces the surge current drawn from the input and switching noise from the device. The input capacitor impedance at the switching frequency shall be less than input source impedance to prevent high frequency switching current passing to the input. Ceramic capacitors with X5R or X7R dielectrics are highly recommended because of their low ESR and small temperature coefficients. For most applications, a 4.7µF capacitor is sufficient.

PC Board Layout

The high current paths (GND, IN and SW) should be placed very close to the device with short, direct and wide traces. Input capacitor C1 needs to be as close as possible to the IN and GND pins. The external feedback resistors shall be placed next to the FB pin. Keep the switching node SW short and away from the feedback network. Figure 2 illustrates an example of PCB layout and signal routing.

Current (A) I

RMS

(A)

Output Capacitor Selection

The output capacitor keeps output voltage ripple small and ensures regulation loop stable. The output capacitor impedance shall be low at the switching frequency. Ceramic capacitors with X5R or X7R dielectrics are recommended. The output ripple ∆V

OUT

≤∆

()

is approximately:

OUT

−×

VVV

××

⎛

OUTINOUT

⎜

ESR

⎜

LfV

⎝

+×

OSCOSCIN

⎞ ⎟

⎟

××

3Cf8

⎠

Figure 2—MP2105 Suggested Layout

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MP2105 – 1MHz 800mA SYNCHRONOUS STEP-DOWN CONVERTER

PACKAGE INFORMATION

TSOT23-5

0.950 TYP

2.90 BSC

0.950 TYP

10°TYP.

(2 plcs)

0.300(Min)

0.500(Max) (5

PLCS)

1.00

Max.

1.60 BSC

0.87±0.03

0.00-0.10

2.80 BSC

SEATING PLANE

0.25 BSC.

Gauge Plane

10° TYP. (2 plcs)

0.400

0.127 TYP.

0°

4°

0°

±0.10

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.

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Datasheet MP2105DJ Datasheet (MPS) [ru]

Specifications and Main Features

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