EVALUATION KIT AVAILABLE
MAX16984
Automotive High-Current Step-Down Converter with
USB Protection/Host Charger Adapter Emulator
General Description
The MAX16984 combines a 5V automotive-grade step-
down converter capable of driving up to 2.5A, a USB host
charger adapter emulator, and USB protection switches
for automotive USB host applications. The USB protection
switches provide high-ESD, short-circuit protection and
feature integrated host-charger port-detection circuitry
adhering to the USB 2.0 Battery Charging Specifica-
tion BC1.2 battery charging specification and Chinese
Telecommunication Industry Standard YD/T 1591-2009.
They also include circuitry for iPod®/iPhone® 1.0A and
iPad® 2.1A dedicated charging modes. The HVD+ and
HVD- ESD protection features include protection to ±15kV
Air/±8kV Contact on the HVD+ and HVD- outputs to the
IEC 61000-4-2 model and 330Ω, 330pF ESD model.
The high-efficiency step-down DC-DC converter
operates from a voltage up to 28V and is protected
from load dump transients up to 42V. The device is opti-
mized for high-frequency operation and includes resistor-
programmable frequency selection from 220kHz to 2.2MHz
to allow optimization of efficiency, noise, and board space
based on application requirements. The converter has
an internal high-side n-channel switch and uses a low
forward-drop freewheeling Schottky diode for rectification.
There is a small low-side n-channel switch to maintain fixed
frequency under light loads. For lower quiescent current
operation requirements, the low side n-channel switch can
be disabled to allow skip mode operation under light loads.
The converter can deliver up to 2.1A of continuous current
at 105°C. The MAX16984S has an integrated spread-
spectrum oscillator to improve EMI performance.
The MAX16984 also includes a USB load current-sense
amplifier and configurable feedback adjustment circuit
designed to provide automatic USB voltage adjustment to
compensate for voltage drops in captive cables associat-
ed with automotive applications. The MAX16984 limits the
USB load current using both a fixed internal peak current
threshold of the DC-DC converter and a user-configurable
external USB load current-sense amplifier threshold.
Benefits and Features
●
Integrated DC-DC and USB Host Charge Emulator
Enables 1-Chip Solution Directly from Car Battery to
Portable Device
• 4.5V to 28V (42V Load Dump) Operating Voltage
• 5V, 2.5A Output Current Capability
• Low-Q Current Skip and Shutdown Modes
• Soft-Start Reduces Inrush Current
●
Low-Noise Features Prevent Interference with AM
Band and Portable Devices
• Fixed-Frequency 220kHz to 2.2MHz Operation
• Forced-PWM Option at No Load
• Spread Spectrum for EMI Reduction
• SYNC Input for Frequency Parking
●
Optimal USB Power and Communication for
Portable Devices
• User-Adjustable Voltage Gain Adjusts Output
Between 5V and 6.15V for Cable Compensation
• ±3% Accuracy User-Adjustable USB Current Limit
•
4Ω USB 2.0 480Mbps/12Mbps Data Switches
• Integrated iPod/iPhone/iPad Charge-Detection
Termination Resistors
• Supports USB BC1.2 Charging Downstream Port
(CDP) and Dedicated Charging Port (DCP) Modes
• Supports Chinese Telecommunication Industry
Standard YD/T 1591-2009
•
Compatible with USB On-the-Go Specification
• High-Speed Pass-Through Mode
●
Robust Design Keeps Vehicle System and
Portable Devices Safe in Automotive Environment
• Short-to-Battery Protection on DC-DC Converter
• Short-to-Battery Protection on USB Pins
• ±25kV Air/±8kV Contact ISO 10605
• ±15kV Air/±8kV Contact IEC 61000-4-2
• ±15kV Air/±8kV Contact (330Ω, 330pF)
• Fault-Indication Active-Low, Open-Drain Output
• Reduced Inrush Current with Soft-Start
• Overtemperature Protection
• -40°C to +125°C Operating Temperature Range
• 28-Pin, 5mm x 5mm, TQFN and Side-Wettable
QFND Packages
Ordering Information
and
Typical Operating Circuit
appear
at end of data sheet.
iPod, iPhone, and iPad are registered trademarks of Apple, Inc.
Applications
●
●
●
●
●
Automotive Radio and Navigation
USB Port for Host and Hub Applications
Automotive Connectivity
Telematics
Dedicated USB Power Charger
19-6627; Rev 3; 4/15
MAX16984
Automotive High-Current Step-Down Converter with
USB Protection/Host Charger Adapter Emulator
Pin Configuration
TOP VIEW
BIAS
SUP
21
BST 22
LX 23
LX 24
SUPSW 25
SUPSW 26
PGND 27
ENBUCK 28
1
FAULT
20
SENSP
19
18
17
16
FBMAX
15
14
13
12
GND
HVD+
HVD-
N.C.
D-
D+
IN
11
10
9
8
7
FBPER
SENSN
SENSO
5
CD1
MAX16984
+
2
SYNC
3
FOSC
4
CD0
TQFN/QFND
Pin Description
PIN
1
2
3
4
5
6
7
8
9
10
11
12
NAME
FAULT
SYNC
FOSC
CD0
CD1
I.C.
FBPER
IN
D+
D-
N.C.
HVD-
FUNCTION
Active-Low Open-Drain Fault Indicator Output. Connect a 100kI pullup resistor to IN.
Synchronization Input. The device synchronizes to an external signal applied to SYNC. When
connected to GND or unconnected, skip mode is allowed under light loads. See Table 1. When
connected to a clock source or IN, forced-PWM (FPWM) mode is enabled.
Resistor-Programmable Switching-Frequency Setting Control Input. Connect a resistor from FOSC to
GND to set the switching frequency.
Charger Detection Configuration Bit 0
Charger Detection Configuration Bit 1
Internal Connection. Must be connected to external GND.
Digital Input. Used to select voltage feedback adjustment percentage.
Logic Enable Input. Connect to I/O voltage of USB transceiver. IN is also used for clamping during
overvoltage events on HVD+ or HVD-. Connect a 1FF ceramic capacitor from IN to GND.
USB Differential Data D+ Input. Connect D+ to low-voltage USB transceiver D+ pin.
USB Differential Data D- Input. Connect D- to low-voltage USB transceiver D- pin.
No Connection
High-Voltage-Protected USB Differential Data D- Output. Connect HVD- directly to the USB
connector D- pin.
I.C.
FBCAP
EP
6
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MAX16984
Automotive High-Current Step-Down Converter with
USB Protection/Host Charger Adapter Emulator
Pin Description (continued)
PIN
13
14
15
16
17
18
19
20
21
22
23, 24
25, 26
27
28
—
NAME
HVD+
GND
FBMAX
FBCAP
SENSO
SENSN
SENSP
BIAS
SUP
BST
LX
SUPSW
PGND
ENBUCK
EP
FUNCTION
High-Voltage-Protected USB Differential Data D+ Output. Connect HVD+ directly to the USB
connector D+ pin.
Analog Ground
Current-Sense Amp Output. Connect a resistor and capacitor to GND to set the voltage-adjustment
bandwidth and the USB DC current level at which maximum voltage-feedback adjustment is reached.
External Capacitor Connection. Connect a 10pF capacitor to GND.
Current-Sense Amp Output. Connect a resistor and capacitor to GND to set the maximum USB DC
current limit.
Current-Sense Amp Negative Input. Connect to negative terminal of current-sense resistor.
DC-DC Converter Feedback Input and Current-Sense Amp Positive Input. Connect to positive
terminal of current-sense resistor and the main output of the converter. Used for internal voltage
regulation loop.
5V Linear Regulator Output. Connect a 1FF ceramic capacitor from BIAS to GND. BIAS powers up
the internal circuitry.
Voltage Supply Input. SUP is the supply pin for the internal linear regulator. Connect a minimum of
4.7FF capacitor from SUP to GND close to the IC.
High-Side Driver Supply. Connect a 0.1FF capacitor from BST to LX.
Inductor Connection. Connect a rectifying Schottky diode between LX and GND. Connect an inductor
from LX to the DC-DC converter output (SENSP).
Internal High-Side Switch-Supply Input. SUPSW provides power to the internal switch. Connect a
4.7FF ceramic capacitor in parallel with a 47FF capacitor from SUPSW to PGND. See the
DC-DC
Input Capacitor
section.
Power Ground
Battery-Compatible Enable Input. Drive ENBUCK low/high to disable/enable the switching regulator.
Exposed Pad. Connect EP to a large-area contiguous copper ground plane for effective power
dissipation. Do not use as the only IC ground connection. EP must be connected to GND.
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MAX16984
Automotive High-Current Step-Down Converter with
USB Protection/Host Charger Adapter Emulator
Detailed Description
IN
Functional Diagram
MAX16984
FAULT
I/O
CONTROL AND
DIAGNOSTICS
CD1
CD0
D-
D+
The MAX16984 combines a 5V/2.1A automotive grade
step-down converter, a USB host charger adapter
emulator, and USB protection switches. It is designed for
high-power USB ports in automotive radio, navigation,
connectivity, and USB hub applications.
The USB protection switches provide high-ESD and
short-circuit protection for the low-voltage internal data
lines of the multimedia processor’s USB transceiver
and support USB Hi-Speed (480Mbps) and USB Full-
Speed (12Mbps) pass-through operation. The MAX16984
features integrated host-charger port-detection circuitry
adhering to the USB 2.0 Battery Charging Specification
BC1.2 and also includes dedicated bias resistors for iPod/
iPhone 1.0A and iPad 2.1A dedicated charging modes.
The high-efficiency step-down DC-DC converter
operates from a voltage up to 28V and is protected from
load-dump transients up to 42V. The device includes
resistor-programmable frequency selection from 220kHz
to 2.2MHz to allow optimization of efficiency, noise, and
board space based on the application requirements. The
converter can deliver up to 2.1A of continuous current at
105NC.
The MAX16984 also includes a high-side current-sense
amplifier and configurable feedback-adjustment circuit
designed to provide automatic USB voltage adjustment to
compensate for voltage drops in captive cables associated
with automotive applications.
HVD-
HVD+
GND
USB AUTO DCP, CDP,
iPhone, iPad
CHARGER DETECTION
SUPSW
BST
SUP
LX
2.1A
FPWM
DC-DC
BIAS
BIAS
PGND
SYNC
FOSC
ENBUCK
REF
I LIMIT
FEEDBACK
ENBUCK
Power-Up and Enabling
System Enable (IN)
IN is used as the main enable to the MAX16984 and is
also used to clamp the D+ and D- pins during an ESD
and short-to-battery on the HVD+ and HVD- pins. This
clamping protects the downstream USB transceiver. The
IN pin contains an overvoltage lockout that disables the
data switches if IN is above V
IN_OVLO
. Bypass IN with a
1FF capacitor and connect it to the same 3.3V supply as
shared with the multimedia processor’s USB transceiver.
If IN is logic-high, the protection switches are enabled
and the USB switches operate in one of four modes per
the CD0 and CD1 inputs. If IN is at a logic-low level, SUP
power consumption is reduced and the device enters a
standby low-quiescent level.
SENSP
SENSO
SENSN
FBMAX
CURRENT-
SENSE AMP
FEEDBACK
ADJUSTMENT
FBPER
FBCAP
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MAX16984
Automotive High-Current Step-Down Converter with
USB Protection/Host Charger Adapter Emulator
Typical Operating Circuit
+3.3V USB
I/O VOLTAGE
1µF
100kΩ
I/O
CONTROL
AND
DIAGNOSTICS
D-
D+
6pF
15nH
15nH
6pF
VBUS
0.1µF
GND
50mΩ
2.2µH
22µF
GND
BST
0.1µF
LX
PGND
SYNC
FOSC
SENSP
SENSN
CURRENT-
SENSE AMP
FEEDBACK
ADJUSTMENT
FBMAX
HVD-
HVD+
FAULT
CD1
CD0
2.2nH
2.2nH
6pF
6pF
OCI
I/O
I/O
3.3V
IN
MAX16984
D-
D+
USB
HOST
CONNECTOR
LOW-
VOLTAGE
µC OR ASIC
WITH
INTEGRATED
USB
TRANSCEIVER
USB AUTO DCP, CDP,
iPod, iPad
CHARGER DETECTION
SUPSW
SUP
BIAS
1µF
EN USB
4.7µF
VBAT
2.1A
FPWM
DC-DC
ENBUCK
FEEDBACK I LIMIT
BIAS
4.7µF
47µF
ENBUCK
REF
SENSO
to ADC
IN
12kΩ
R
SENSO
C
SENSO
R
FBMAX
FBPER
C
FBMAX
FBCAP
10pF
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