MP5408M_技术文档

MP5408M

36V, 6A, Frequency Programmable,

Step-Down Converter with

Smart, Dual, USB Charging Ports

The Future of Analog IC Technology

DESCRIPTION

FEATURES



EMI Reduction Technique

The MP5408M integrates a monolithic, step-

down, switch-mode converter with two USB

current-limit switches and charging port

identification circuitry for each port. The

MP5408M achieves 6A of output current with

excellent load and line regulation over a wide

input-supply range.

Wide 6V to 36V Operating Input Voltage

Range



Selectable Output Voltage: 5.1V, 5.17V, and

5.3V



90mV Line Drop Compensation

Accurate USB1/USB2 Output Current Limit

18mΩ/15mΩ Low R_DS(ON)Internal Buck

Power MOSFETs

The output of the USB switch is current-limited.

Both USB ports support DCP schemes for

battery charging specification (BC1.2), divider

mode, 1.2V/1.2V mode and USB Type-C

5V@3A DFP mode, eliminating the need for

outside user interaction.



13mΩ/13mΩ

USB1/USB2 Power MOSFETs

Low

R_DS(ON)

Internal



Frequency Adjustable (235kHz to 2.2MHz)

Forced Continuous Conduction Mode (CCM)

Operation

Full protection features include hiccup current

limiting, output over-voltage protection (OVP),

and thermal shutdown.



Hiccup Current Limit for both Buck and USB

Supports DCP Schemes for BC1.2, Divider

Mode, and 1.2V/1.2V Mode

The MP5408M requires a minimal number of



Supports USB Type-C 5V @ 3A DFP Mode

±8kV HBM ESD Rating for USB, DP, and

DM pins

readily

available,

standard,

external

components and is available in a QFN-26

(5mmx5mm) package.



Available in

Package

a

QFN-26 (5mmx5mm)

APPLICATIONS



USB Dedicated Charging Ports (DCP)

USB Type-C 5V @ 3A DFP

Automotive Cigarette Lighter Adapters

Power Supply for Linear Chargers

All MPS parts are lead-free, halogen-free, and adhere to the RoHS directive. For

MPS green status, please visit MPS website under Quality Assurance. “MPS”

and “The Future of Analog IC Technology” are registered trademarks of

Monolithic Power Systems, Inc.

TYPICAL APPLICATION

60

55

50

45

40

35

30

25

20

15

10

5

0

30M 50 80

200 300 500 800 1G

400

60 100M

MP5408M Rev. 1.1

8/14/2017

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1

MP5408M – 36V, 6A, STEP-DOWN CONVERTER W/ DUAL USB CHARGING PORTS

ORDERING INFORMATION

Part Number*

Package

Top Marking

MP5408MGU

QFN-26 (5mmx5mm)

See Below

* For Tape & Reel, add suffix –Z (e.g. MP5408MGU–Z)

TOP MARKING

MPS: MPS prefix

YY: Year code

WW: Week code

MP5408M: Product code of MP5408MGU

LLLLLLL: Lot number

PACKAGE REFERENCE

TOP VIEW

DM2

19

DM1

23

DP1

22

CC3

18

CC2

24

EN

21

DP2

20

17

1

2

3

4

CC4

USB2

OUT

IN

CC1

USB1

OUT

IN

16

15

14

25 OUT

26 SW

PGND

5

13

PGND

6

7

8

9

10

11

OUT_SEL

12

FREQ

AGND VCC

SW

BST

QFN-26 (5mmx5mm)

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MP5408M – 36V, 6A, STEP-DOWN CONVERTER W/ DUAL USB CHARGING PORTS

ABSOLUTE MAXIMUM RATINGS ⁽¹⁾

Thermal Resistance

QFN-26 (5mmx5mm)

θ_JA

θ_JC

Supply voltage (V_IN) ..................................... 40V

(5)

V_SW....................................-0.3V (-5V for <10ns)

to V_IN+ 0.3V (43V for <10ns)

JESD51-7 ........................... 44........ 9.... °C/W

50mmx50mm 4-Layer PCB ... 20........ 2.... °C/W

V

_BST................................................... V_SW+ 5.5V

(2)

NOTES:

VEN...........................................-0.3V to +10V

V_OUT,V_USB.....................................-0.3V to +6.5V

All other pins................................-0.3V to +5.5V

Continuous power dissipation (T_A= +25°C) ⁽³⁾

QFN-26 (5mmx5mm)............................... 6.25W

Junction temperature................................150°C

Lead temperature .....................................260°C

Storage temperature................ -65°C to +150°C

1) Absolute maximum ratings are rated under room temperature

unless otherwise noted. Exceeding these ratings may

damage the device.

2) For details on EN’s ABS max rating, please refer to the EN

Control section on page 11.

3) The maximum allowable power dissipation is a function of the

maximum junction temperature T_J(MAX), the junction-to-

ambient thermal resistance θ_JA, and the ambient temperature

T_A. The maximum allowable continuous power dissipation at

any ambient temperature is calculated by P_D(MAX) = (T_J

(MAX)-T_A)/θ_JA. Exceeding the maximum allowable power

dissipation produces an excessive die temperature, causing

the regulator to go into thermal shutdown. Internal thermal

shutdown circuitry protects the device from permanent

damage. Measured on 4 layers PCB (50mmx50mm).

4) The device is not guaranteed to function outside of its

operating conditions.

Recommended Operating Conditions ⁽⁴⁾

Operation input voltage range ............6V to 36V

Output current................ 3A (USB1), 3A (USB2)

Operating junction temp. (T_J)... -40°C to +125°C

5) Measured on JESD51-7 and 4-layer PCB.

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MP5408M – 36V, 6A, STEP-DOWN CONVERTER W/ DUAL USB CHARGING PORTS

ELECTRICAL CHARACTERISTICS

V_IN= 12V, V_EN= 5V, CC1 = CC3 = 5.1kΩ, T_J= -40°C to +125°C ⁽⁶⁾, typical value is tested at T_J=

+25°C, unless otherwise noted.

Parameter

Symbol

Condition

V_EN= 0V

Min

Typ

13

1

Max

18

2

Units

μA

Supply current (shutdown)

I_IN

I_Q1

No switching

mA

Supply current (quiescent)

CC floating, V_BUSdisabled,

T_J= +25°C

I_Q2

200

300

μA

EN rising threshold

EN hysteresis

V_{EN Rising}

V_{EN HYS}

I_EN

-3%

4

1.235

200

8

+3%

V

mV

μA

C

V

EN pull-up current

Thermal shutdown ⁽⁷⁾

Thermal hysteresis ⁽⁷⁾

VCC regulator

12

T_TSD

165

20

T_{TSD_HYS}

V_CC

4.2

4.6

4.5

1

4.85

3

VCC load regulation

Step-Down Converter

V_{CC LOG}

I_CC= 50mA

%

V_INunder-voltage lockout

threshold rising

V_{IN_UVLO}

5

5.4

V

V_INunder-voltage lockout

threshold hysteresis

V_{UVLO_HYS}

700

mV

HS switch on resistance

LS switch on resistance

R_{DSON HS}

R_{DSON LS}

18

15

mΩ

OUT_SEL = low, T_J= +25°C

OUT_SEL = float, T_J= +25°C

-1.5%

-1%

5.1

5.17

+1.5%

+1%

Output voltage

V_OUT

V

OUT_SEL = float, T_J= -40°C

to +125°C

-2%

5.17

5.3

+2%

+1.5%

6.25

OUT_SEL = high, T_J= +25°C -1.5%

Output over-voltage

protection

V_{OVP_R}

5.45

5.3

5.85

V

Output OVP recovery

Output to ground resistance

Low-side current limit

V_{OVP F}

R_Discharge

I_{LS LIMIT}

5.7

175

-2

6.1

V

kΩ

A

V_EN= 0V, V_SW= 36V or 0V,

T_J= +25°C

1

5

Switch leakage

SW_LKG

μA

V_EN= 0V, V_SW= 36V or 0V,

T_J= -40°C to +125°C

High-side current limit

I_LIMIT

F_SW1

F_SW2

F_SW3

F_SW4

D_MAX

40% duty cycle

Pull R_FREQto GND

R_FREQ= 66.5kꢀ

R_FREQ= 9.53kꢀ

R_FREQ= float

9

13

235

350

2200

450

95

A

Oscillator frequency

Maximum duty cycle

kHz

%

350

530

FREQ = 450kHz

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MP5408M – 36V, 6A, STEP-DOWN CONVERTER W/ DUAL USB CHARGING PORTS

ELECTRICAL CHARACTERISTICS (continued)

V_IN= 12V, V_EN= 5V, CC1 = CC3 = 5.1kΩ, T_J= -40°C to +125°C ⁽⁶⁾, typical value is tested at T_J=

+25°C, unless otherwise noted.

Parameter

Symbol

T_{OFF MIN}

T_{ON_MIN}

Condition

Min

Typ

110

130

Max

Units

ns

Minimum off time

Minimum on time ⁽⁷⁾

ns

Output from 10% to 90%,

T_J= +25°C

Soft-start time

T_SS

2

ms

V

USB Switch (USB1 and USB2)

Under-voltage lockout

threshold rising

V_{USB_UVR}

3.7

4

4.3

Under-voltage lockout

threshold hysteresis

V_{USB_UVHYS}

R_{DSON SW}

R_{DIS_USB}

V_{USB OV}

I_Limit1

200

13

mV

mꢀ

kꢀ

V

Switch on resistance

Output discharge

resistance

Apply 5V voltage on USB

output, CC pin float

500

5.6

USB OVP clamp

5.3

3.1

5.9

3.8

V_OUTdrops 10% , Type-C

3.45

mode

Current limit

A

T_J= +25°C , V_OUTdrops 10%,

Type-A mode

I_Limit2

2.6

2.75

2.9

Iout=2.4A , V_OUT= 5V,

T_J= +25°C

Line drop compensation

V_BUSsoft-start time

V_{DROP_COM}

T_SS

90

2

mV

ms

Output from 10% to 90%

1

3

OC, V_OUTdrops 10%,

T_J= +25°C

3.5

5

6.5

Hiccup mode on time

T_{HICP_ON2}

ms

s

OC, V_OUTdrops 10%,

T_J= -40°C to +125°C

3

5

2

7

Hiccup mode off time

T_{HICP OFF}

V_OUTconnected to GND

BC1.2 DCP Mode

V_DP= 0.8V, I_DM= 1mA,

T_J= +25°C

85

155

160

DP and DM short

resistance

R_{DP/DM_Short}

ꢀ

V_DP= 0.8V, I_DM= 1mA,

T_J= -40°C to +125°C

Divider Mode

DP/DM output voltage

DP/DM output impedance

1.2V/1.2V Mode

V_{DP/DM Divider}

R_{DP/DM_Divider}

2.55

14

2.7

22

2.85

30

V

T_J= +25°C

kꢀ

T_J= -40°C to +125°C

12

34

V

_OUT= 5V, T_J= +25°C

1.12

1.1

1.2

1.28

1.3

DP/DM output voltage

V_{DP/DM_1.2V}

V

V_OUT= 5V, T_J= -40°C to

+125°C

T_J= +25°C

70

60

105

140

150

DP/DM output impedance

R_{DP/DM_1.2V}

kꢀ

T_J= -40°C to +125°C

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MP5408M – 36V, 6A, STEP-DOWN CONVERTER W/ DUAL USB CHARGING PORTS

ELECTRICAL CHARACTERISTICS (continued)

V_IN= 12V, V_EN= 5V, CC1 = CC3 = 5.1kΩ, T_J= -40°C to +125°C ⁽⁶⁾, typical value is tested at T_J=

+25°C, unless otherwise noted.

Parameter

Symbol Condition

Min

Typ

Max

Units

USB Type-C 5V @ 3A Mode – CC1, CC2, CC3, and CC4

CC resistor to disable

Type-C mode

R_A

CC1 and CC3

70

90

kꢀ

CC voltage to enable

V_CONN

V_Ra

0.75

2.45

V

CC voltage to enable V_BUS

CC detach threshold

V_Rd

0.9

V_Detach

2.75

CC voltage falling

debounce timer

T_{CC_debounce}V_BUSenable deglitch

T_{PD_debounce}V_BUSdisable deglitch

100

10

144

15

200

20

ms

CC voltage rising

debounce timer

V_CONNcomes from the buck output

V_CONNoutput power

P_VCONN

with some series resistance,

T_J= +25°C

1

W

NOTES:

6) All min/max parameters are tested at T_J= 25°C. Limits over temperature are guaranteed by design, characterization, and correlation.

7) Guaranteed by design and characterization test.

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MP5408M – 36V, 6A, STEP-DOWN CONVERTER W/ DUAL USB CHARGING PORTS

TYPICAL PERFORMANCE CHARACTERISTICS

V_IN= 12V, V_OUT= 5.17V, L = 8µH, T_A= 25°C, unless otherwise noted.

100

60

55

50

45

40

35

30

25

20

15

10

5

100

96

90

80

70

60

50

40

30

20

10

Vin=6V

Vin=12V

Vin=36V

92

88

84

80

0

30M 50 80

200 300 500 800 1G

400

0

1

2

3

4

5

6

7

0

0.5

1

1.5

2

2.5

3

60 100M

MP5408M Rev. 1.1

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MP5408M – 36V, 6A, STEP-DOWN CONVERTER W/ DUAL USB CHARGING PORTS

TYPICAL PERFORMANCE CHARACTERISTICS (continued)

V_IN= 12V, V_OUT= 5.17V, L = 8µH, T_A= 25°C, unless otherwise noted.

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MP5408M – 36V, 6A, STEP-DOWN CONVERTER W/ DUAL USB CHARGING PORTS

PIN FUNCTIONS

QFN 5x5

Pin #

Name Description

Configuration channel. CC1 is used to detect connections and configure the

interface across the USB1 Type-C cables and connectors. Once a connection is

established, CC1 or CC2 is reassigned to provide power over the V_CONNpin of the

plug.

1

CC1

2

USB1

OUT

USB1 output.

3, 15, 25

Buck output. OUT is the power input for USB1 and USB2.

Supply voltage. IN is the drain of the internal power device and provides power to the

entire chip. The MP5408M operates from a 6V to 36V input voltage. The input

capacitor (C_IN) prevents large voltage spikes at the input. Place C_INas close to the IC

as possible.

4, 14

IN

Power ground. PGND is the reference ground of the regulated output voltage. PGND

5, 13

PGND requires extra care during the PCB layout. Connect PGND with copper traces and

vias.

6

7

AGND Analog ground. Connect AGND to PGND.

VCC

SW

Internal 4.5V LDO regulator output. Decouple VCC with a 1µF capacitor.

Switch output. Use a wide PCB trace to make the connection.

8, 9, 26

Bootstrap. A 0.22µF capacitor is connected between SW and BST to form a floating

supply across the high-side switch driver.

10

11

BST

Buck output voltage set. By setting OUT_SEL to low, float, or high, three different

output voltages can be achieved: 5.1V, 5.17V, or 5.3V.

OUT_SEL

Switching frequency program input. Connect a resistor from FREQ to GND to set

12

16

FREQ the switching frequency. Float FREQ or connect FREQ to VCC for the default 450kHz

frequency. Connect FREQ to ground for a 235kHz internal frequency.

USB2

USB2 output.

Configuration channel. CC4 is used to detect connections and configure the

interface across the USB2 Type-C cables and connectors. Once a connection is

established, CC3 or CC4 is reassigned to provide power over the V_CONNpin of the

plug.

17

CC4

Configuration channel. CC3 is used to detect connections and configure the

interface across the USB2 Type-C cables and connectors. Once a connection is

established, CC3 or CC4 is reassigned to provide power over the V_CONNpin of the

plug.

18

19

CC3

DM2

D- data line to USB2 connector. DM2 is the input/output used for handshaking with

portable devices.

D+ data line to USB2 connector. DP2 is the input/output used for handshaking with

portable devices.

20

21

22

DP2

EN

On/off control input. EN has an internal auto pull-up with a 8µA current source.

D+ data line to USB1 connector. DP1 is the input/output used for handshaking with

portable devices.

DP1

D- data line to USB1 connector. DM1 is the input/output used for handshaking with

portable devices.

23

24

DM1

CC2

Configuration channel. CC2 is used to detect connections and configure the

interface across the USB1 Type-C cables and connectors. Once a connection is

established, CC1 or CC2 is reassigned to provide power over the V_CONNpin of the

plug.

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MP5408M – 36V, 6A, STEP-DOWN CONVERTER W/ DUAL USB CHARGING PORTS

BLOCK DIAGRAM

Figure 1: Functional Block Diagram

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MP5408M – 36V, 6A, STEP-DOWN CONVERTER W/ DUAL USB CHARGING PORTS

Enable (EN) Control

OPERATION

The MP5408M has an enable (EN) control pin.

An internal 8μA pull-up current allows EN to be

floated for automatic start-up. Pull EN high or

float EN to enable the IC. Pull EN low to disable

the IC.

BUCK CONVERTER SECTION

The MP5408M integrates

a

monolithic,

synchronous, rectified, step-down, switch-mode

converter with internal power MOSFETs and

two USB current-limit switches with charging-

port auto-detection. The MP5408M offers a

compact solution that achieves 6A of

continuous output current with excellent load

and line regulation over a wide input supply

range.

EN is clamped internally using a 7.6V series

Zener diode and a 10V break-down voltage of

the ESD cell (see Figure 2).

Connect EN through a pull-up resistor to V_INto

enhance the EN pull-up current ability. This

requires limiting the EN voltage below 10V or

limiting EN input current below 500μA if the EN

pull-up voltage is larger than 10V.

The MP5408M operates in a fixed-frequency,

peak-current-mode control to regulate the

output voltage. The internal clock initiates the

pulse-width modulation (PWM) cycle, which

turns on the integrated high-side power

MOSFET (HS-FET). The HS-FET remains on

until its current reaches the value set by the

COMP voltage (V_COMP). When the power switch

is off, it remains off until the next clock cycle

begins. If the duty cycle reaches 95% (450kHz

switching frequency) in one PWM period, the

current in the power MOSFET does not reach

the COMP-set current value, and the power

MOSFET turns off.

For example, if connecting EN to V_IN= 36V,

then R_PULLUP≥ (36V - 10V) / 500μA = 52kꢀ.

Figure 2: Zener Diode between EN and GND

Setting the Switching Frequency

Error Amplifier (EA)

Connect a resistor from FREQ to ground to set

the switching frequency (see Table 1). The

value of the frequency can be calculated

approximately with Equation (1):

The error amplifier (EA) compares the internal

feedback voltage against the internal reference

(REF) and outputs V_COMP. V_COMPcontrols the

power MOSFET current. The optimized, internal

compensation network minimizes the external

component count and simplifies the control loop

design.

1000000

FREQ(kHz) 

42.5R^FREQ(KΩ) 53.7

(1)

The frequency vs. R_FREQis shown in Figure 3.

Internal VCC Regulator

2200

The 4.5V internal regulator powers most of the

internal circuitries. This regulator takes V_INand

operates in the full V_INrange. When V_IN

exceeds 4.5V, the output of the regulator is in

full regulation. If V_INis less than 4.5V, the output

decreases with V_IN. VCC requires an external

1µF ceramic decoupling capacitor.

1700

1200

700

After the buck output starts up, the internal VCC

LDO output is biased by the buck output

through a Schottky diode.

200

0

20 40 60 80 100 120

Figure 3: Switching Frequency vs. R_FREQ

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MP5408M – 36V, 6A, STEP-DOWN CONVERTER W/ DUAL USB CHARGING PORTS

Table 1: Recommended Resistor Values for

Typical Switching Frequency

R_FREQ

F_S

(kΩ)

(kHz)

0

235

350

66.5

NS

450

Figure 5: EMI Reduction

45.8

22.3

14.6

9.53

500

Under-Voltage Lockout (UVLO)

1000

1500

2200

Under-voltage lockout (UVLO) protects the chip

from operating at an insufficient supply voltage.

The UVLO comparator monitors the input

voltage. The UVLO rising threshold is 5V, and

its falling threshold is 4.3V.

Two internal comparators monitor FREQ's logic

voltage to enable FREQ to float or short to GND.

During power-up, there is another internal

source current on FREQ. The frequency is

locked at 450kHz when a voltage greater than

2V and a current greater than 8µs is sensed on

FREQ. The frequency is locked at 235kHz

when a voltage less than 0.1V and a current

greater than 8µs is sensed on FREQ. Leave

FREQ floating or connect FREQ to VCC to

achieve the 450kHz default switching frequency.

Short FREQ to ground to achieve a 235kHz

frequency (see Figure 4).

Internal Soft Start (SS)

Soft start (SS) prevents the converter output

voltage from overshooting during start-up.

When the chip starts up, the internal circuitry

generates a SS voltage that ramps up from 0V

to 5V. When SS is lower than REF, the error

amplifier uses SS as the reference. When SS is

higher than REF, the error amplifier uses REF

as the reference. The SS time is set to 2ms

internally. If the output of the MP5408M is pre-

biased to a certain voltage during start-up, the

IC disables the switching of both the high-side

and low-side switches until the voltage on the

internal SS capacitor exceeds the internal

feedback voltage.

Forced CCM Operation

The MP5408M works in forced continuous

conduction mode (CCM) continuously. The

MP5408M operates in a fixed switching

frequency regardless of whether it is operating

in light load or full load. The advantage of CCM

is the controllable frequency, smaller output

ripple, and sufficient bootstrap charge time, but

it also has low efficiency at light-load condition.

A proper inductance should be selected to

avoid triggering the low-side switch's negative

current limit (typically 2A, from SW to GND). If

the negative current limit is triggered, the low-

side switch turns off, and the high-side switch

turns on when the internal clock comes around.

Figure 4: Switching Frequency Functional Block

Electromagnetic Interference (EMI)

Based on MPS’s flip-chip package technology,

the MP5408M integrates two sets of EMI filters

to reduce the input path’s parasitic inductance

dramatically. Simultaneously, the input pin and

GND pin are assigned on two sides

symmetrically, partially cancelling the magnetic

field inside those two filters (see Figure 5). The

magnetic field in the overlap area (A1) is

partially cancelled.

Buck Over-Current Protection (OCP)

Using the above technique, the radiated

emission performance is improved greatly.

The MP5408M has a cycle-by-cycle over-

current limit when the inductor peak current

exceeds the current-limit threshold, and the FB

voltage drops below the under-voltage (UV)

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MP5408M – 36V, 6A, STEP-DOWN CONVERTER W/ DUAL USB CHARGING PORTS

threshold (typically 50% below the reference).

triggering. Then V_COMPand the internal supply

rail are pulled down. The floating driver is not

subject to this shutdown command.

Once UV is triggered, the MP5408M enters

hiccup mode to restart the part periodically.

This protection mode is especially useful when

the output is dead-shorted to ground. This

reduces the average short-circuit current greatly,

alleviates thermal issues, and protects the

regulator. The MP5408M exits hiccup mode

once the over-current condition is removed.

Buck Output Impedance

The Buck doesn't involve output discharge

function during EN shutdown. After EN

shutdown, there is only two feedback resistor

connected to the OUT pin, which has a typical

resistance of 175kꢀ in total. Refer to the block

diagram.

Buck Output Over-Voltage Protection (OVP)

The MP5408M has output over-voltage

protection (OVP). If the output is higher than

5.85V, the high-side switch stops turning on.

The low-side switch turns on to discharge the

output voltage until the output decreases to

5.7V, and then the chip resumes normal

operation.

USB CURRENT-LIMIT SWITCH SECTION

Over-Current Protection (OCP) and Hiccup

The MP5408M integrates two USB current-limit

switches. The MP5408M provides built-in soft-

start circuitry which controls the rising slew rate

of the output voltage to limit inrush current and

voltage surges.

Floating Driver and Bootstrap Charging

When the load current reaches the current-limit

threshold the USB power MOSFET works in

constant current-limit mode (see Figure 7). If

the over-current limit condition lasts more than

5ms (V_OUTdoes not drop too low), the

corresponding USB channel enters hiccup

mode with 5ms of on-time and 2s of off-time.

Another USB channel works normally.

An external bootstrap capacitor powers the

floating power MOSFET driver. This floating

driver has its own UVLO protection. The

UVLO’s rising threshold is 2.2V with a

hysteresis of 150mV. The bootstrap capacitor

voltage is regulated internally by VIN and VCC

through D1, D2, M1, C4, L1 and C2 (see Figure

5). BST capacitor C4 voltage will be charged

up quickly by VCC through M1. The 2.5μA input

to BST current source also can charge the BST

capacitor when low-side switch doesn't turn-on.

Figure 7: Over-Current Limit

After the soft start finishes, if the USB output

voltage is lower than 3.5V and lasts longer than

50µs, the MP5408M enters hiccup without

having to wait 5ms (see Figure 8). This can

prevent abnormal thermal rise during the

constant resistor (CR) load over-current case.

Figure 6: Internal Bootstrap Charging Circuit

Start-Up and Shutdown

If both IN and EN exceed their respective

thresholds, the chip is enabled. The reference

block starts first, generating a stable reference

voltage and current, and then the internal

regulator is enabled. The regulator provides a

stable supply for the remaining circuitries.

Three events can shut down the chip: EN low, IN

low, and thermal shutdown. In shutdown, the

signaling path is blocked to avoid any fault

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MP5408M – 36V, 6A, STEP-DOWN CONVERTER W/ DUAL USB CHARGING PORTS

USB Output Discharge and Impedance

Each USB switch involves a fast discharge path

that can quickly discharge the external output

capacitor's energy during power shutdown. This

function will be active when the CC pins are

released or the part is disabled (input voltage is

under UVLO or enable off). The discharge path

is turned off when USB output voltage is

Figure 8: Over-Current Limit for CR Load

discharged lower than 50mV. After turn-off the

fast discharge path, there is only a high

impedance resistor (typical 500kꢀ) from USB1

or USB2 to ground.

Fast Response for Short-Circuit Protection

(SCP)

If the load current increases rapidly due to a

Auto-Detection

short-circuit event, the current may exceed the

current limit threshold before the control loop is

able to respond. If the current reaches the 7A

secondary current limit level, a fast turn-off

circuit activates to turn off the power MOSFET.

This can help limit the peak current through the

switch, keeping the buck output voltage from

dropping too much and affecting another USB

channel. The total short-circuit response time is

less than 1µs.

The MP5408M integrates a USB dedicated

charging port auto-detect function. This function

recognizes most mainstream portable devices

and supports the following charging schemes:

USB battery charging specification BC1.2/

Chinese Telecommunications Industry standard

YD/T 1591-2009



Apple divider mode

When the fast turn-off function is triggered, the

MOSFET turns off for 100µs and restarts with a

soft start. During the restart process, if the short

still remains, the MP5408M regulates the gate

voltage to hold the current at a normal current

limit level.

1.2V/1.2V mode

USB Type-C 5V @ 3A DFP mode

The auto-detect function is a state machine that

supports all of the DCP charging schemes

above. Connect DP and DM with 150ꢀ resistor

for DCP mode.

Output Line Drop Compensation

USB Type-C Mode and V_CONN

The MP5408M can compensate for an output

voltage drop, such as high impedance caused

by a long trace, to maintain a fairly constant

output voltage at the load-side voltage.

For USB Type-C solutions, two pins (CC1 and

CC2) on the connector are used to establish

and manage the source-to-sink connection. The

general concept for setting up

a

valid

The internal comparator compares the current-

sense output voltage of the two current-limit

switches and uses the larger current-sense

output voltage to compensate for the line drop

voltage.

connection between a source and a sink is

based on being able to detect terminations

residing in the product being attached. To aid in

defining the functional behavior of CC, a pull-up

(Rp) and pull-down (Rd 5.1kꢀ) termination

model is used based on a pull-up resistor and

pull-down resistor (see Figure 9).

The line drop compensation amplitude

increases linearly as the load current increases.

It also has an upper limitation. The line drop

compensation at a 3A output current is 90mV.

USB Output Over-Voltage Clamp

To protect the device at the cable terminal, the

USB switch output has a fixed over-voltage

protection (OVP) threshold. When the input

voltage is higher than the OVP threshold, the

output voltage is clamped at 5.6V.

Figure 9: Current Source/Pull-Down CC Model

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MP5408M – 36V, 6A, STEP-DOWN CONVERTER W/ DUAL USB CHARGING PORTS

Initially, a source exposes independent Rp

detect a sink. The presence of an Rd pull-

down resistor on CC1 or CC2 indicates that

a sink is being attached. The value of Rp

indicates the initial USB Type-C current

level supported by the host. The

MP5408M’s Rp is 10kꢀ, which represents a

3A current level.

terminations on its CC1 and CC2 pins, and a

sink exposes independent Rd terminations on

its CC1 and CC2 pins. The source-to-sink

combination of this circuit configuration

represents a valid connection. To detect this,

the source monitors CC1 and CC2 for a voltage

lower than its unterminated voltage. The choice

of Rp is a function of the pull-up termination

voltage and the source’s detection circuit. This

indicates that either a sink, a powered cable, or

a sink connected via a powered cable has been

attached. Prior to the application of V_CONN, a

powered cable exposes Ra (typically 1kꢀ) on

its V_CONNpin. Ra represents the load on V_CONN

plus any resistive elements to ground. In some

cable plugs, this might be a pure resistance,

and in others, it may simply be the load.

3. The source uses the CC pull-down

characteristic to detect and determine which

CC pin is intended to supply VCONN (when

Ra is discovered).

4. Once a sink is detected, the source enables

V_BUSand V_CONN.

5. The source monitors the continued

presence of Rd to detect a sink detach.

When a detach event is detected, the

source is removed, and V_BUSand V_CONN

return to step 2.

The source must be able to differentiate

between the presence of Rd and Ra to know

whether there is a sink attached and where to

apply V_CONN. The source is not required to

source V_CONNunless Ra is detected.

Disable Type-C Mode (Type-A Mode)

During the MP5408M initial start-up, the IC

sources 10μA for 20μs on CC1. If the CC1

voltage falls into a 400mV to 1.2V voltage range,

USB1 latches in Type-A mode unless the part is

re-enabled. Type-C mode is disabled, so CC is

attached, the detach logic is, disabled and V_BUS

is always enabled. The current limit changes to

a Type-A spec. The same logic is implemented

on CC3 for USB2.

Two special termination combinations on the

CC pins as seen by a source are defined for

directly attached accessory modes: Ra/Ra for

audio adapter accessory mode, and Rd/Rd for

debug accessory mode (see Figure 10 and

Table 2).

To trigger Type-A mode, the external pull-down

resistor should be 70 - 90kꢀ. Do not connect

extra capacitors on CC1 and CC3.

In normal Type-C mode application, a 1nF

capacitor should be added on CC1 and CC3

respectively to avoid falsely trigger Type-A

mode. Refer to the typical schematic for detail.

The MP5408M also supports debug mode and

audio adapter accessory mode in Type-C

applications. If two Ra resistors pull down CC1

and CC2, or two Rd resistors pull down CC1

and CC2, there is no action inside the IC (V_BUS

is not enabled).

Figure 10: CC Functional Block

A port that behaves as a source has the

following functional characteristics.

Thermal Shutdown

Thermal shutdown prevents the chip from

operating at exceedingly high temperatures.

When the silicon die temperature exceeds

165°C, the entire chip shuts down. When the

temperature falls below its lower threshold

(typically 145°C), the chip is enabled.

1. The source uses a MOSFET to enable or

disable the power delivery across V_BUS

.

Initially, the source is disabled.

2. The source supplies pull-up resistors (Rp)

on CC1 and CC2 and monitors both to

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MP5408M – 36V, 6A, STEP-DOWN CONVERTER W/ DUAL USB CHARGING PORTS

Table 2: CC Logic Truth Table

V_CONN

(USB1)

VCONN

(USB2)

EN

CC of USB1 ⁽⁸⁾

CC of USB2 ⁽⁸⁾

Buck

USB1

USB2

X

Disabled

Enabled

Disabled

Enabled

Disabled

Enabled

Disabled

Enabled

Disabled

Enabled

Disabled

Enabled

Disabled

Enabled

Disabled

Enabled

Disabled

Enabled

Disabled

Enabled

0

AUDIO

DEBUG

“A” ⁽⁹⁾

Rd, Ra

Open

AUDIO

DEBUG

“A”

Rd, Ra

Open

AUDIO

DEBUG

“A”

Rd, Ra

Open

Open or AUDIO

or DEBUG

1

Rd, Ra

1

“A”

NOTES:

8) USB1 and USB2 are symmetric to each other.

9) "A" means Type-A mode. CC1 (CC3 for USB2) is requested to be pulled down by a 80.6kꢀ resistor to enter this mode.

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MP5408M – 36V, 6A, STEP-DOWN CONVERTER W/ DUAL USB CHARGING PORTS

The input capacitor can be electrolytic, tantalum,

APPLICATION INFORMATION

Selecting the Inductor

or ceramic. When using an electrolytic capacitor,

place two additional high-quality ceramic

capacitors as close to IN as possible. Estimate

the input voltage ripple caused by the

capacitance with Equation (5):

For most applications, use an inductor with a

DC current rating at least 25% higher than the

maximum load current. Select an inductor with

a small DC resistance for optimum efficiency.

For most designs, the inductor value can be

derived with Equation (2):









I_LOAD

V_OUT

V





 1



IN

f_SC1

V

IN

V



IN

(5)

V_OUT(V  V_OUT

)

IN

Selecting the Buck Output Capacitor

L₁

V  I_L f_OSC

IN

(2)

The device requires an output capacitor (C2) to

maintain the DC output voltage. Estimate the

output voltage ripple with Equation (6):

Where ∆I_Lis the inductor ripple current.

Choose the inductor ripple current to be

approximately 30% of the maximum load

current. The maximum inductor peak current

can be calculated with Equation (3):



 

V_OUT







V_OUT

1

V_OUT



 1

 R



ESR



 

f_SL₁

V

8 f_SC2



^IN 

(6)

Where L₁is the inductor value, and RESR is the

equivalent series resistance (ESR) value of the

output capacitor.

I_L

I_L(MAX) I_LOAD



2

(3)

For an electrolytic capacitor, the ESR

dominates the impedance at the switching

frequency. For simplification, the output ripple

can be approximated with Equation (7):

Selecting the Buck Input Capacitor

The input current to the step-down converter is

discontinuous and therefore requires

a

capacitor to supply AC current while

maintaining the DC input voltage. Use low ESR

capacitors for optimum performance. Ceramic

capacitors with X5R or X7R dielectrics are

highly recommended because of their low ESR

and small temperature coefficients. 100µF

electrolytic and 50µF ceramic capacitors are

recommended in applications with a 235kHz

switching frequency.

V_OUT





ꢁV_OUT



 1

R_ESR







f_SL₁

V

IN



(7)

A 100 - 270μF capacitor with an ESR less than

50mꢀ (e.g.: polymer capacitor or tantalum

capacitor) and three 10μF ceramic capacitors

are recommended in the application.

For CLA applications, set the switching

frequency to be 235kHz for better thermal

performance (see Table 3).

Since the input capacitor (C1) absorbs the input

switching current, it requires an adequate ripple

current rating. The RMS current in the input

capacitor can be estimated with Equation (4):

Table 3: Recommended External Components

Switching

Frequency

Input

Cap

Buck Output

Capacitor

Inductor







V_OUT

V_IN

V_OUT

V_IN



I_C1 I_LOAD



 1









50µF

ceramic

cap +

100µF E-

cap

(4)

30µF

ceramic cap

+ 270µF

235kHz

450kHz

8μH

The worst-case condition occurs at V_IN= 2V_OUT

,

shown in Equation (5):

Polymer cap

I_LOAD

50µF

ceramic

cap +

100µF E-

cap

I_C1



30µF

ceramic cap

+ 270µF

2

(5)

4.7μH

For simplification, choose an input capacitor

with an RMS current rating greater than half of

the maximum load current.

Polymer cap

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MP5408M – 36V, 6A, STEP-DOWN CONVERTER W/ DUAL USB CHARGING PORTS

ESD Protection for I/O Pins

Higher ESD levels should be considered for all

USB I/O pins. The MP5408M features high

ESD protection up to ±8kV human body model

on DP, DM, USB1, and USB2, and ±5.5kV

human body model on CC1 through CC4. The

ESD structures can withstand high ESD both in

normal operation and when the device is

powered off. To further extend DP and DM's

ESD level for covering complicated application

environments,

additional

resistors

and

capacitors can be added (see Figure 11).

Similar R-C networks cannot be added on CC1

or CC2 because the CC line must support

200mA of current and 300kHz of signaling.

Additional ESD diodes can be added on the CC

pins.

Figure 11: Recommended I/O Pins ESD

Enhancing

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MP5408M – 36V, 6A, STEP-DOWN CONVERTER W/ DUAL USB CHARGING PORTS

PC Board Layout ⁽¹⁰⁾

Efficient PCB layout is critical for stable

operation and thermal dissipation. For best

results, refer to Figure 12 and follow the

guidelines below.

1. Use short, direct, and wide traces to

connect OUT.

2. Add vias under the IC.

Top Layer

3. Route the OUT trace on both PCB layers.

4. Place the buck output ceramic capacitor

C2A and C2B on one side and C2C on the

other side.

VIN

GND

5. Add a large copper plane for PGND.

6. Add multiple vias to improve thermal

dissipation.

7. Connect AGND to PGND.

8. Place a large copper plane for SW, USB,

and USB2.

Middle Layer 1

9. Route the USB1 and USB2 traces on both

PCB layers.

10. Add multiple vias.

11. Place two ceramic input decoupling

capacitors as close to IN and PGND as

possible to improve EMI performance.

GND

12. Place the VCC decoupling capacitor as

close to VCC as possible.

Middle Layer 2

NOTE:

10) The recommended layout is based on the Typical

Application Circuits in Figure 13 through Figure 15.

Place C2C at one side of MP5408M

Place C2A, C2B at the other side of MP5408M

Bottom Layer

Figure 12: Recommended Layout

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MP5408M – 36V, 6A, STEP-DOWN CONVERTER W/ DUAL USB CHARGING PORTS

TYPICAL APPLICATION CIRCUITS

C4

220nF

L1

8µH

10

L1

8,9,26

4.7µH

4,14

C1D

+

C2

3,15,25

11

2

270µF

ESR<50mΩ

C2A

10µF 10µF 10µF

C1

100µF

C2B C2C

C1A

22µF

+

C1B

22µF

C1C

4.7µF

10µF

21

C5

10µF

23

MP5408M

R2

150Ω

12

7

22

24

1

Type-C

16

C7

1nF

C6

C3

1µF

10µF

19

R3

150Ω

Type-C

20

17

18

C8

1nF

6

5,13

Figure 13: Dual USB Type-C 5V/3A DFP Ports ⁽¹¹⁾

Figure 14: Dual USB Type-A 5V/2.4A Ports ⁽¹¹⁾

Figure 15: One Type-C 5V/3A DFP Port, One Type-A 5V/2.4A Port ⁽¹¹⁾

NOTE:

11) See Figure 11 for I/O pins’ ESD protection enhancing details.

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MP5408M – 36V, 6A, STEP-DOWN CONVERTER W/ DUAL USB CHARGING PORTS

PACKAGE INFORMATION

QFN-26 (5mmx5mm)

NOTICE: The information in this document is subject to change without notice. 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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2121


型号：	MP5408M
厂家：	MONOLITHIC POWER SYSTEMS
描述：	36V, 6A, Frequency Programmable, Step-Down Converter with Smart, Dual, USB Charging Ports
文件：	总21页 (文件大小：895K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

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