MPQ4475M Datasheet by Monolithic Power Systems Inc.
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MPQ4475M
36V, 2.5A, Frequency Selectable,
Step-Down Converter
with Single USB Charging Port
AEC-Q100 Qualified
MPQ4475M Rev.1.01 www.MonolithicPower.com 1
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© 2017 MPS. All Rights Reserved.
The Future of Analog IC Technology
DESCRIPTION
The MPQ4475M integrates a monolithic, step-
down, switch-mode converter with a single USB
current-limit switch and a charging port
identification circuit. The MPQ4475M achieves
2.5A of continuous output current with excellent
load and line regulation over a wide input
supply range.
The output of the USB switch is current-limited.
The MPQ4475M provides a USB dedicated
charging port (DCP), which supports Battery
Charging Specification 1.2 (BC1.2), divider
mode, and 1.2V/1.2V mode without the need of
outside user interaction.
The output voltage has programmable line drop
compensation.
Full protection features includes hiccup current
limiting, output over-voltage protection (OVP), and
thermal shutdown.
The MPQ4475M requires a minimum number of
readily available, standard, external components
and is available in a QFN-25 (4mmx4mm)
package.
FEATURES
EMI Reduction Technique
Wide 7V to 36V Operating Input Voltage
Range
Fixed 5V Output Voltage with Line Drop
Compensation
Accurate USB Output Current Limit
40m/32m Low RDS(ON) Internal Buck
Power MOSFETs
24m Low RDS(ON) Internal USB Power
MOSFET
350kHz / 250kHz / 150kHz Frequency
Selectable
Programmable Line Drop Compensation
Output Over-Voltage Protection (OVP)
Hiccup Current Limit
Supports DCP Scheme for BC1.2, Divider
Mode, and 1.2V/1.2V Mode
±8kV HBM ESD Rating for USB, DP, and
DM Pins
Available in a QFN-25 (4mmx4mm)
Package
Available in AEC-Q100 Grade 1
Less than 1s Short-Circuit Recovery
(Hiccup Mode Off-Time)
APPLICATIONS
Automotive USB Smart Charging Ports
A
ll MPS parts are lead-free, halogen-free, and adhere to the RoHS directive. Fo
r
MPS green status, please visit the MPS website under Quality Assurance. “MPS”
and “The Future of Analog IC Technology” are registered trademarks o
f
Monolithic Power Systems, Inc.
TYPICAL APPLICATION
LOAD CURRENT (A)
Efficiency vs.
Load Current
65
70
75
80
85
90
95
100
0 0.5 1 1.5 2 2.5
V
IN
=7V
V
IN
=12V
mP ' MPQ4475M — 36V, 2.5A, STEP-DOWN CONVERTER W/ SINGLE USB CHARGING PORT
mam
M4475M
LLLLLL
MPQ4475M – 36V, 2.5A, STEP-DOWN CONVERTER W/ SINGLE USB CHARGING PORT
MPQ4475M Rev.1.01 www.MonolithicPower.com 2
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ORDERING INFORMATION
Part Number* Package Top Marking
MPQ4475MGR QFN-25 (4mmx4mm) See Below
MPQ4475MGR-AEC1
* For Tape & Reel, add suffix –Z (e.g. MPQ4475MGR–Z)
TOP MARKING
MPS: MPS prefix
Y: Year code
WW: Week code
M4475M: Product code of MPQ4475MGR and MPQ4475MGR-AEC1
LLLLLL: Lot number
PACKAGE REFERENCE
TOP VIEW
1
12
11
6
1723
16
24
25
5
22 21
2
3
4
789
10
13
14
15
181920
DM
DP
NC
NC
VDROP
VCC
AGND
AGND
NC
OUT
IN
PGND
PGND
BST
SW
EN
FREQ
PGND
PGND
IN
OUT
USB
DM
OUT
SW
QFN-25 (4mmx4mm)
mP ' MF04475M — 36v, 2.5A, STEP-DOWN CONVERTER wx SINGLE usa CHARGING PORT
TJ
MPQ4475M – 36V, 2.5A, STEP-DOWN CONVERTER W/ SINGLE USB CHARGING PORT
MPQ4475M Rev.1.01 www.MonolithicPower.com 3
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ABSOLUTE MAXIMUM RATINGS (1)
Supply voltage (VIN) ..................................... 40V
VSW .................................................. -0.3V (-5V for <10ns) to
VIN + 0.3V (43V for <10ns)
VBST ................................................... VSW + 6.5V
VEN ...............................................-0.3V to 10V
(2)
All other pins ................................ -0.3V to +6.5V
Continuous power dissipation (TA = +25°C) (3)
QFN-25 (4mmx4mm) ................................. 2.8W
Junction temperature ................................ 150°C
Lead temperature ..................................... 260°C
Storage temperature ................ -65°C to +150°C
Recommended Operating Conditions (4)
Operation input voltage range ............ 7V to 36V
Output current ................................ 2.5A for USB
Operating junction temp. (TJ). .. -40°C to +125°C
Thermal Resistance (5) θJA θJC
QFN-25 (4mmx4mm) .............. 44 ....... 9 .... °C/W
NOTES:
1) Exceeding these ratings may damage the device.
2) For details of 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 TJ (MAX), the junction-to-
ambient thermal resistance JA, and the ambient temperature
TA. The maximum allowable continuous power dissipation at
any ambient temperature is calculated by PD (MAX) = (TJ
(MAX)-TA)/JA. Exceeding the maximum allowable powe
r
dissipation produces an excessive die temperature, causing
the regulator to go into thermal shutdown. Internal thermal
shutdown circuitry protects the device from permanent
damage.
4) The device is not guaranteed to function outside of its
operating conditions.
5) Measured on JESD51-7, 4-layer PCB.
mP V MPQ4475M — 36V, 2.5A, STEP-DOWN CONVERTER W/ SINGLE USB CHARGING PORT
MPQ4475M – 36V, 2.5A, STEP-DOWN CONVERTER W/ SINGLE USB CHARGING PORT
MPQ4475M Rev.1.01 www.MonolithicPower.com 4
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© 2017 MPS. All Rights Reserved.
ELECTRICAL CHARACTERISTICS
VIN = 12V, VEN = 5V, TJ = -40°C to +125°C, typical value is tested at TJ = +25°C, unless otherwise
noted.
Parameter Symbol Condition Min Typ Max Units
Supply current (shutdown) IIN VEN = 0V,TJ = +25°C 1 A
VEN = 0V, TJ = -40°C to +125°C 5
Supply current (quiescent) IQOL
No switching 1.6 2.5 mA
EN rising threshold VEN Risin
g
1.33 1.43 1.52 V
EN hysteresis VEN Fallin
g
110 140 170 mV
EN input current IEN
VEN = 2V, TJ = +25°C 1.1 1.8 2.5
A
VEN = 2V,TJ = -40°C to +125°C 0.8 1.8 3
VEN = 0V 0
Thermal shutdown
(
6
)
T
STD 165 °C
Thermal hysteresis(6) T
STD_HYS 20 °C
VCC regulator VCC 4.75 5.1 5.45 V
VCC load regulation VCC_LOG I
CC = 5mA 1 2 %
Step-Down Converter
VIN under-voltage lockout
threshold rising VIN_UVLO T
J = +25°C 5.2 5.7 6.2 V
VIN under-voltage lockout
threshold hysteresis VUVLO_HYS 1 V
HS switch on resistance RDS(ON)_HS 40 m
LS switch on resistance RDS(ON)_LS 32 m
Output voltage VOUT
7V < VIN < 36V, no load, TJ = +25°C 5 5.05 5.1
V
7V < VIN < 36V, no load,
TJ = -40°C to +125°C 4.95 5.05 5.15
Output over-voltage
protection VOVP_R 5.65 6 6.4 V
OVP recovery VOVP F T
J = -40°C to +125°C 5.4 5.75 6.1 V
Switch leakage SWLKG
VEN = 0V, VSW = 36V, TJ = +25°C 1
A
VEN = 0V, VSW = 36V,
TJ = -40°C to +125°C 5
Current limit(6) I
LIMIT Over 0-90% duty cycle 4 A
Oscillator frequency
fSW1 FREQ = high, TJ = +25°C 310 350 410
kHz
FREQ = high, TJ = -40°C to +125°C 300 350 420
fSW2 FREQ = low, TJ = +25°C 220 250 300
FREQ = low, TJ = -40°C to +125°C 190 250 330
fSW3 FREQ = float, TJ = +25°C 125 150 180
FREQ = float, TJ = -40°C to +125°C 110 150 185
Maximum duty cycle DMAX FREQ = 350kHz 84 88 %
Minimum on time(6) T
ON_MIN T
J = +25°C 130 ns
Soft-start time tSS
Output from 10% to 90%, TJ = +25°C 1 1.65 2.3
ms
Output from 10% to 90%,
TJ = -40°C to +125°C 0.9 1.65 2.4
mP V MPQ4475M — 36V, 2.5A, STEP-DOWN CONVERTER W/ SINGLE USB CHARGING PORT
MPQ4475M – 36V, 2.5A, STEP-DOWN CONVERTER W/ SINGLE USB CHARGING PORT
MPQ4475M Rev.1.01 www.MonolithicPower.com 5
6/2/2017 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2017 MPS. All Rights Reserved.
ELECTRICAL CHARACTERISTICS (continued)
VIN = 12V, VEN = 5V, TJ = -40°C to +125°C, typical value is tested at TJ = +25°C, unless otherwise
noted.
Parameter Symbol Condition Min Typ Max Units
USB Switch
Under-voltage lockout
threshold rising VUSB_UVR TJ = +25°C 3.8 4 4.3 V
TJ = -40°C to +125°C 3.75 4 4.33
Under-voltage lockout
threshold hysteresis VUSB_UVHYS 220 270 320 mV
Switch-on resistance RDSON_SW 24 m
Current limit ILimit T
J = +25°C 2.6 2.75 2.9 A
Line drop compensation
VDROP_COM1 Max load 2.4A, VDROP = float,
TJ = +25°C 300 400 500 mV
VDROP_COM2 Max load 2.4A, VDROP = high 280 mV
VDROP_COM3 Max load 2.4A, VDROP = GND 130 mV
FREQ, VDROP high level VHIGH VCC -
0.4V V
FREQ, VDROP middle
level VMIDDLE 2.5 V
FREQ, VDROP low level VLOW 0.4 V
VBUS soft-start time TSS
VOUT = 5V, from 10% to 90%,
TJ = +25°C 1 1.6 2.2
ms
VOUT = 5V, from 10% to 90%,
TJ = -40°C to +125°C 0.9 1.6 2.4
Discharge resistance RDCHG TJ = +25°C 50 70
TJ = -40°C to +125°C 50 75
On time of hiccup mode
THICP_ON1 V
OUT = 5V, VBUS connected to GND 3(6)
ms
THICP_ON2
VOUT = 5V, VBUS > 2V, OC,
TJ = +25°C 3.5 5 6.5
VOUT = 5V, VBUS > 2V, OC,
TJ = -40°C to +125°C 3 5 7
Off time of hiccup mode THICP_OFF
VOUT = 5V, VBUS connected to GND,
TJ = +25°C 0.35 0.5 0.65
s
VOUT = 5V, VBUS connected to GND,
TJ = -40°C to +125°C 0.2 0.5 0.8
BC1.2 DCP Mode
DP and DM short
resistance RDP/DM_Short
VDP = 0.8V, IDM = 1mA, TJ = +25°C 125 155
VDP = 0.8V, IDM = 1mA,
TJ = -40°C to +125°C 125 160
Divider Mode
DP/DM output voltage VDP/DM_Divider VOUT = 5V, TJ = +25°C 2.54 2.7 2.82 V
VOUT = 5V, TJ = -40°C to +125°C 2.5 2.7 2.85
DP/DM output impedance RDP/DM_Divider TJ = +25°C 16 22 30 k
TJ = -40°C to +125°C 14 22 34
mP ' MPQ4475M — 36V, 2.5A, STEP-DOWN CONVERTER W/ SINGLE USB CHARGING PORT
MPQ4475M – 36V, 2.5A, STEP-DOWN CONVERTER W/ SINGLE USB CHARGING PORT
MPQ4475M Rev.1.01 www.MonolithicPower.com 6
6/2/2017 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2017 MPS. All Rights Reserved.
ELECTRICAL CHARACTERISTICS (continued)
VIN = 12V, VEN = 5V, TJ = -40°C to +125°C, typical value is tested at TJ = +25°C, unless otherwise
noted.
Parameter Symbol Condition Min Typ Max Units
1.2V/1.2V Mode
DP/DM output voltage VDP/DM_1.2V VOUT = 5V, TJ = +25°C 1.16 1.25 1.34 V
VOUT = 5V, TJ = -40°C to +125°C 1.15 1.25 1.35
DP/DM output impedance RDP/DM_1.2V TJ = +25°C 55 68 80 k
TJ = -40°C to +125°C 50 68 93
NOTE:
6) Guaranteed by design.
mp ' MF04475M — 36v, 2.5A, STEP-DOWN CONVERTER W/ SINGLE USB CHARGING PORT
Thermal Test
2 Layer PCB, 4]ch x1 38cm
35290 No Am‘law
vwmzv‘ USEJOUT=2 5A
EFFICIENCY (“/n)
Thermal Test
2 Layer PCB. 4.75m x1 38cm
1352519 No Axrflow
V‘N=12\A USBJOUfiMA
MPQ4475M – 36V, 2.5A, STEP-DOWN CONVERTER W/ SINGLE USB CHARGING PORT
MPQ4475M Rev.1.01 www.MonolithicPower.com 7
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TYPICAL PERFORMANCE CHARACTERISTICS
VIN = 12V, VOUT = 5V, L = 22µH, fS = 250kHz, TA = 25°C, unless otherwise noted.
LINE DROP COMPENSATION (mV)
LOAD CURRENT (A) LOAD CURRENT (A)
Efficiency vs.
Load Current
Line Drop Compensation
vs. Load Current
0
50
100
150
200
250
300
350
400
450
0 0.5 1 1.5 2 2.5
V
DROP
=Float
V
DROP
=V
CC
V
DROP
=GND
65
70
75
80
85
90
95
100
0 0.5 1 1.5 2 2.5
V
IN
=7V
V
IN
=12V
mp ' MPO4475M — 36v, 2.5A, STEP-DOWN CONVERTER wx SINGLE usa CHARGING PORT
1ms/d‘v. stldiv. ZmSIdiv.
MPQ4475M – 36V, 2.5A, STEP-DOWN CONVERTER W/ SINGLE USB CHARGING PORT
MPQ4475M Rev.1.01 www.MonolithicPower.com 8
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TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 12V, VOUT = 5V, L = 22µH, fS = 250kHz, TA = 25°C, unless otherwise noted.
V
SW
10V/div.
USB
V
OUT
/AC
10mV/div.
Buck
V
OUT
5V/div.
I
L
500mA/div.
V
SW
10V/div.
USB
V
OUT
/AC
10mV/div.
Buck
V
OUT
5V/div.
I
L
2A/div.
V
SW
10V/div.
USB
V
OUT
2V/div.
Buck
V
OUT
5V/div.
USB
I
OUT
2A/div.
V
SW
10V/div.
USB
V
OUT
2V/div.
Buck
V
OUT
5V/div.
USB
I
OUT
2A/div.
USB
V
OUT
2V/div.
USB
I
OUT
2A/div.
V
SW
5V/div.
USB
V
OUT
2V/div.
Buck
V
OUT
5V/div.
USB
I
OUT
2A/div.
V
SW
5V/div.
USB
V
OUT
2V/div.
Buck
V
OUT
5V/div.
USB
I
OUT
2A/div.
Output Ripple
V
IN
= 12V, USB_I
OUT
= 0A
Output Ripple
V
IN
= 12V, USB_I
OUT
= 2.5A
Power Startup
V
IN
= 12V, USB_I
OUT
= 0A
Power Startup
V
IN
= 12V, USB_I
OUT
= 2.5A,
CRL Load
Power Shutdown
V
IN
= 12V, USB_I
OUT
= 0A
Power Shutdown
V
IN
= 12V, USB_I
OUT
= 2.5A,
CRL Load
USB Over Current
Protection
mP V MPQ4475M — 36V, 2.5A, STEP-DOWN CONVERTER W/ SINGLE USB CHARGING PORT
copper
FREQ
y
for
MPQ4475M – 36V, 2.5A, STEP-DOWN CONVERTER W/ SINGLE USB CHARGING PORT
MPQ4475M Rev.1.01 www.MonolithicPower.com 9
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PIN FUNCTIONS
QFN 4x4
Pin # Name Description
1, 23 DM D- data line to the USB connector. DM is the input/output used for
handshaking with portable devices.
2 USB
USB output.
3, 14, 24 OUT Buck output. OUT is the USB’s power input. The internal circuit senses the
OUT voltage and regulates it at 5V.
4, 13 IN
Supply voltage. The MPQ4475M operates from a 7V to 36V input voltage. CIN
prevents large voltage spikes at the input. Place CIN as close to the IC as
possible. IN is the drain of the internal power device and the power supply for
the whole chip.
5, 6, 11, 12 PGND
Power ground. PGND is the reference ground of the regulated output voltage
and requires extra care during PCB layout. Connect PGND to GND with copper
traces and vias.
7 FREQ
Frequency selection. Float FREQ to set the frequency at 150kHz. Pull FREQ
to ground to set the frequency at 250kHz. Pull FREQ high to set the frequency
at 350kHz.
8 EN
On/off control input.
9, 25 SW Switch output. Use wide PCB traces to make the connection.
10 BST
Bootstrap. Connect a 0.1µF capacitor between SW and BST to form a floating
supply across the high-side switch driver.
15 NC No connection. NC can be connected to OUT for better thermal dissipation.
16, 17 AGND Analog ground. Connect AGND to PGND.
18 VCC Internal 5V LDO regulator output. Decouple VCC with a 0.22µF capacitor.
19 VDROP
Line drop compensation selection. Refer to the EC table for detailed
specifications.
20, 21 NC No connection. NC must be left floating.
22 DP
D+ data line to the USB connector. DP is the input/output used for
handshaking with portable devices.
mP V MPQ4475M — 36V, 2.5A, STEP-DOWN CONVERTER W/ SINGLE USB CHARGING PORT
MPQ4475M – 36V, 2.5A, STEP-DOWN CONVERTER W/ SINGLE USB CHARGING PORT
MPQ4475M Rev.1.01 www.MonolithicPower.com 10
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BLOCK DIAGRAM
Σ
Bootstrap
Regulator
HS
Driver
LS
Driver
VCC
Control
Logic
Oscillator
VCC
Regulator
Reference
Line Drop
Compensation
IN
EN
VDROP
VCC
OUT
AGND
BST
Current Sense
Amplifier
Current Limit
Comparator
PWM Comparator
OVP Comparator
Error Amplifier
SW
PGND
Curent
Sense
Charge
Pump
Control
Logic
Thermal
Sense
UVLO
Discharge
USB
Auto
Detect
2.7V
1.2V
DP
DM
NC
FREQ
Rtop
Rbot
Current
Limit
SS
1MΩ
12KΩ
7.6V
Discharge
Figure 1: Functional Block Diagram
mP ' MF04475M — 36v, 2.5A, STEP-DOWN CONVERTER W/ SINGLE usa CHARGING PORT
EN
D 1M0 12kQ EN
.6V Logic
GND
MPQ4475M – 36V, 2.5A, STEP-DOWN CONVERTER W/ SINGLE USB CHARGING PORT
MPQ4475M Rev.1.01 www.MonolithicPower.com 11
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OPERATION
BUCK CONVERTER SECTION
The MPQ4475M integrates a monolithic,
synchronous, rectified, step-down, switch-mode
converter with internal power MOSFETs and a
USB current-limit switch with charging port auto-
detection. The MPQ4475M offers a very compact
solution that achieves 2.5A of continuous output
current with excellent load and line regulation
over a wide input supply range.
The MPQ4475M operates in a fixed-frequency,
peak-current-mode control to regulate the output
voltage. The internal clock initiates the 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 (VCOMP). When the power switch is
off, it remains off until the next clock cycle begins.
If the duty cycle reaches 88% (350kHz switching
frequency) in one PWM period, the current in the
power MOSFET cannot reach the COMP-set
current value, and the power MOSFET is forced
off.
Error Amplifier (EA)
The error amplifier (EA) compares the internal
feedback voltage against the internal 1V
reference (REF) and outputs a COMP voltage,
which controls the power MOSFET current. The
optimized internal compensation network
minimizes the external component count and
simplifies the control loop design.
Internal VCC Regulator
The 5V internal regulator powers most of the
internal circuitries. This regulator takes the VIN
input and operates in the full VIN range. When VIN
exceeds 5.0V, the output of the regulator is in full
regulation. When VIN is less than 5.0V, the output
decreases with VIN. VCC requires an external
0.22µF ceramic decoupling capacitor.
Enable Control (EN)
The MPQ4475M has an enable control pin (EN).
Pulling EN high enables the IC; pulling EN low
disables the IC. Connect EN to VIN through a
resistor for automatic start-up. An internal 1M
resistor from EN to GND allows EN to float to
shut down the IC. EN is clamped internally using
a 7.6V series Zener diode (see Figure 2).
Connect the EN input through a pull-up resistor
to any voltage connected to VIN. EN requires
limiting the EN input current below 230A and
the amplitude of the voltage source below 10V to
prevent damage to the Zener diode.
For example, if connecting 36V to VIN, then
RPULLUP (36V - 10V) / 230µA = 113k.
Figure 2: Zener Diode between EN and GND
Under-Voltage Lockout (UVLO)
Under-voltage lockout (UVLO) protects the chip
from operating at an insufficient supply voltage.
The MPQ4475M’s UVLO comparator monitors
the input voltage. The UVLO rising threshold is
5.7V, and its falling threshold is 4.7V.
Internal Soft Start (SS)
The 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 1.65ms internally.
If the output of the MPQ4475M 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.
mP ' MF04475M — 36v, 2.5A, STEP-DOWN CONVERTER W/ SINGLE usa CHARGING PORT
MPQ4475M – 36V, 2.5A, STEP-DOWN CONVERTER W/ SINGLE USB CHARGING PORT
MPQ4475M Rev.1.01 www.MonolithicPower.com 12
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Buck Over-Current-Protection (OCP)
The MPQ4475M uses 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)
threshold (typically 70% below the reference).
Once UV is triggered, the MPQ4475M 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 MPQ4475M exits hiccup mode
once the over-current condition is removed.
Buck Output Over-Voltage Protection (OVP)
The MPQ4475M buck converter has output over-
voltage protection (OVP). If the output is higher
than 6V, the high-side switch stops turning on.
The low-side switch turns on to discharge the
output voltage until the output decreases to
5.75V, and the chip then resumes normal
operation. If the output over-voltage cannot be
discharged to 5.75V, the low-side switch is
turned off after the inductor current reaches the
negative current limit. The low-side switch turns
on again when the next clock cycle is triggered.
Floating Driver and Bootstrap Charging
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 through D1, M1, C4,
L1, and C2 (see Figure 3). If VBST - VSW exceeds
5V, U1 regulates M1 to maintain a 5V BST
voltage across C4.
VIN
VOUT
D1
M1
BST
C4
L1
SW
U1
5V
C2
Figure 3: Internal Bootstrap Charging Circuit
Start-Up and Shutdown
If both VIN 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, VIN
low, and thermal shutdown. During shutdown, the
signaling path is blocked first to prevent any fault
triggering. VCOMP and the internal supply rail are
then pulled down. The floating driver is not
subject to this shutdown command.
Buck Output Discharge
The buck portion involves a discharge function
that provides a resistive discharge path for the
external output capacitor. This function is active
when the part is disabled (input voltage is under
UVLO, enable off), and is done in a very limited
amount of time. After VCC is discharged below
1V, the buck output discharge resistor is
disconnected.
mP ' MFO4475M — 36v, 2.5A, STEP-DOWN CONVERTER wx SINGLE usa CHARGING PORT
MPQ4475M – 36V, 2.5A, STEP-DOWN CONVERTER W/ SINGLE USB CHARGING PORT
PRELIMINARY SPECIFICATIONS SUBJECT TO CHANGE
MPQ4475M Rev.1.01 www.MonolithicPower.com 13
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USB CURRENT-LIMIT SWITCH SECTION
Current-Limit Switch
The MPQ4475M integrates a single-channel USB
current-limit switch. The switch provides built-in,
soft-start circuitry that controls the rising slew
rate of the output voltage to limit inrush current
and voltage surges.
When the load current reaches the current-limit
threshold (typically 2.75A), the USB power
MOSFET switches into foldback current limit
mode (70% of the current limit) (see Figure 4).
When the over-current limit condition lasts longer
than 3ms, the device enters hiccup mode with
3ms of on time and 0.5s of off time.
5
0
Vout(V)
Current Limit
Fold-back
Current Limit
Iout(A)
3ms t
Figure 4: Over-Current Limit
Output Line Drop Compensation
The MPQ4475M can compensate for an output-
voltage drop (such as high impedance caused by
a long trace) to maintain a fairly constant 5V
load-side voltage.
The MPQ4475M uses the internal current-sense
output voltage of the current-limit switch to
compensate for the line drop voltage. Since the
trace resistance is different for different cables,
the MPQ4475M provides selectable line drop
compensation through VDROP. The line drop
compensation amplitude increases linearly as the
load current increases, and also has an upper
limitation.
USB Output Over-Voltage Protection (OVP)
To protect the device at the cable terminal, the
USB switch output uses a dynamic over-voltage
protection (OVP) threshold. The MPQ4475M
adjusts the OVP threshold based on different
USB loading currents.
The MPQ4475M uses intelligent line drop
compensation and a dynamic over-voltage
protection control scheme to ensure that the
voltage at the cable terminal meets the 4.75V -
5.25V specification.
USB Output Discharge
USB portion involves a discharge function that
provides a resistive discharge path for the
external output capacitor. The function is active
when the part is disabled (input voltage is under
UVLO, enable off), and is done in a very limited
amount of time.
Auto-Detection
The MPQ4475M integrates the USB dedicated
charging port auto-detect function, which
recognizes most mainstream portable devices.
The MPQ4475M supports the following charging
schemes:
USB Battery Charging Specification BC1.2/
Chinese Telecommunications Industry
Standard YD/T 1591-2009
Divider Mode
1.2V/1.2V Mode
The auto-detect function utilizes a state machine
that supports all of the above DCP charging
schemes.
After power startup, MPQ4475M will enter default
divider mode, output voltage is 5.05V with full line
drop compensation. If MPQ4475M enters BC1.2
short mode or 1.2V/1.2V mode, output voltage
will change to 5.25V with half line drop
compensation. By doing this, the device uses
BC1.2 mode or 1.2V/1.2V mode that can charge
at its full rated current.
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 again.
mP ' MF04475M — 36v, 2.5A, STEP-DOWN CONVERTER W/ SINGLE usa CHARGING PORT
MPQ4475M – 36V, 2.5A, STEP-DOWN CONVERTER W/ SINGLE USB CHARGING PORT
MPQ4475M Rev.1.01 www.MonolithicPower.com 14
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© 2017 MPS. All Rights Reserved.
APPLICATION INFORMATION
Selecting the Inductor
Use an inductor with a DC current rating at
least 25% percent higher than the maximum
load current for most applications. Select an
inductor with a small DC resistance for optimum
efficiency. For most designs, the inductor value
can be derived with Equation (1):
OUT IN OUT
1
IN L OSC
V(VV)
LVIf
(1)
Where IL is 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 (2):
2
I
II L
LOAD)MAX(L
(2)
Typically, a 22H inductance is recommended
to improve EMI.
Selecting the Buck Input Capacitor
The input current to the step-down converter is
discontinuous and therefore requires a
capacitor to supply AC current to the step-down
converter while maintaining the DC input
voltage. Use low ESR capacitors for best
performance. Ceramic capacitors with X5R or
X7R dielectrics are highly recommended
because of their low ESR and small
temperature coefficients. For CLA applications,
a low ESR 100F electrolytic capacitor and two
10F ceramic capacitors are recommended for
EMI reduction.
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 (3):
IN
OUT
IN
OUT
LOAD1C V
V
1
V
V
II (3)
The worst-case condition occurs at VIN = 2VOUT,
shown in Equation (4):
2
I
ILOAD
1C (4)
For simplification, choose an input capacitor
with an RMS current rating greater than half of
the maximum load current.
The input capacitor can be electrolytic, tantalum,
or ceramic. When using electrolytic capacitors,
place two additional high-quality ceramic
capacitors as close to IN as possible. The input
voltage ripple caused by the capacitance can
be estimated with Equation (5):
LOAD OUT OUT
IN IN
SIN
IV V
V1
fC1V V
(5)
Selecting the Buck Output Capacitor
The device requires an output capacitor (C2) to
maintain the DC output voltage. Estimate the
output voltage ripple with Equation (6):
OUT OUT
OUT ESR
S1 IN S
VV 1
V1R
fL V 8fC2
(6)
Where L1 is the inductor value, and RESR is the
equivalent series resistance (ESR) value of the
output capacitor.
For electrolytic capacitors, the ESR dominates
the impedance at the switching frequency. For
simplification, the output ripple can be
approximated with Equation (7):
OUT OUT
OUT ESR
IN
S1
VV
V1R
fL V
(7)
The characteristics of the output capacitor
affect the stability of the regulatory system. A
low ESR electrolytic capacitor is recommended
for low output ripple and good control loop
stability. For CLA applications, a 270µF polymer
or electrolytic capacitor with ~20m ESR and
one 1µF ceramic capacitor are recommended.
mp ' MPQ4475M — 36V, 2.5A, STEP-DOWN CONVERTER W/ SINGLE usa CHARGING PORT
MPQ4475M – 36V, 2.5A, STEP-DOWN CONVERTER W/ SINGLE USB CHARGING PORT
MPQ4475M Rev.1.01 www.MonolithicPower.com 15
6/2/2017 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2017 MPS. All Rights Reserved.
PCB Layout Guidelines
Efficient PCB layout is critical for stable
operation and thermal dissipation. For best
results, refer to Figure 5 and follow the
guidelines below.
1. Connect OUT with short, direct, and wide
traces.
2. Add vias under the IC.
3. Route the OUT trace on both PCB layers.
4. Use a large copper plane for PGND.
5. Add multiple vias for better thermal
dissipation.
6. Connect AGND to PGND.
7. Use a large copper plane for SW and USB.
8. Place the USB output capacitor close to
USB.
9. Place two ceramic input decoupling
capacitors as close to IN and PGND as
possible to improve EMI performance.
10. Place the VCC decoupling capacitor as
close to VCC as possible.
Top Layer
Mid1 Layer
Mid2 Layer
Bottom Layer
Figure 5: Recommended Layout
mP ' MPQ4475M — 36V, 2.5A, STEP-DOWN CONVERTER W/ SINGLE USB CHARGING PORT
-I|-—)I—
):
.
..
—|
MPQ4475M – 36V, 2.5A, STEP-DOWN CONVERTER W/ SINGLE USB CHARGING PORT
MPQ4475M Rev.1.01 www.MonolithicPower.com 16
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© 2017 MPS. All Rights Reserved.
TYPICAL APPLICATION CIRCUIT
MPQ4475M
PGND
EN
IN
AGND
SW
USB
OUT
VCC
BST
VDROP
DM
DP
NC
U
S
B
D-
D+ USB, 2.5A
Float
FREQ
R1
300k
C5
10F
C1B
10F
C3
220nF
C1A
10F
+
+
C1
100F
C4
100nF
L1
22H
C2A
1F
C2
270F
20m ESR
VIN
12V
C1C
10F
L2
2.2µH
Optional filter for improving
conduction EMI
4,13
8
19
7
18
16, 17
5,6,11,12
9,25
3,14,24
2
1, 23
22
20,21
10
No Connection
NC 15
Figure 6: VIN = 12V, USB = 5V/2.5A
I'I'IP
PIN 1 In
MARKING
PIN 1 In
INnEx ANEA
TOP VIEW
EFE
SIDE VIEW
MM?
. WI III
RECOMMENDED LAND PATTERN
. MPQ4475M — 36V, 2.5A, STEP-DOWN CONVERTER W/ SINGLE USB CHARGING PORT
jI—IVITIi I r—I" Pll1ll‘l
0.2m"- "F
I
\
A?
“L I II I I9“
BOTTOM VIEW
NOTE:
1) LAND PATTERN 0F FINN AND 13‘15 HAVE THE
SAME LENGTH AND WIDTH.
2) LAND PATTERN 0F PINZA AND 25 HAVE THE
SAME LENGTH AND WIDTH.
2) ALL DIMENSIONS ARE IN MILLIMETERS
2) LEAD COPLANARITV SHALL BE 0.10
MILLIMETERS MAX.
3) JEDEC REFERENCE IS MO—220.
4) DRAWING IS NOT TO SCALE.
MPQ4475M – 36V, 2.5A, STEP-DOWN CONVERTER W/ SINGLE USB CHARGING PORT
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.
MPQ4475M Rev.1.01 www.MonolithicPower.com 17
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PACKAGE INFORMATION
QFN-25 (4mmx4mm)
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