MP4689
100V Input, 1A High
Power LED Driver
MP4689 Rev. 1.01 www.MonolithicPower.com 1
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© 2018 MPS. All Rights Reserved.
DESCRIPTION
The MP4689 is a high voltage input step-down
switching regulator to deliver a constant current
of up to 1A to high power LEDs. It integrates a
high-side high voltage power MOSFET with a
current limit of 2.5A (typical value). The wide
4.5V to 100V input range accommodates a
variety of step-down applications, making it
ideal for automotive, industrial and general
lighting applications. Hysteresis current mode
control is applied for very fast response, which
makes the 20kHz dimming frequency possible.
MPS’s proprietary feedback control scheme
minimizes the number of external components
while delivering a LED current with typical ±3%
accuracy.
The switching frequency is up to 1MHz, thus
allowing for small component size. The thermal
shut down and short circuit protection provide
reliable, fault tolerant operations. A 170µA
quiescent current allows its use in battery-
powered applications.
The MP4689 is available in SOIC8 with
exposed pad package.
FEATURES
Wide 4.5V to 100V Operating Input Range
No Output Capacitor Required
±3% LED Current Accuracy
Hysteretic Control: No Compensation
Up to 1MHz Switching Frequency
Up to 20kHz Dimming Frequency
Dedicated PWM Dimming Control Input
Short Circuit Protection with Integrated High
Side MOSFET
Thermal Shut Down
200mV Reference Voltage for High
Efficiency
Up to 95% Efficiency
170μA Quiescent Current
Available in SOIC-8 with Exposed Pad
Package
APPLICATIONS
High Power LED Driver
Automotive, Industry and General Lighting
Constant Current Source
All MPS parts are lead-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
MP4689 – 100V INPUT, 1A HIGH POWER LED DRIVER
MP4689 Rev. 1.01 www.MonolithicPower.com 2
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ORDERING INFORMATION
Part Number*
Package
Top Marking
MP4689DN
SOIC-8 EP
MP4689
* For Tape & Reel, add suffix –Z (e.g. MP4689DN–Z);
For RoHS compliant packaging, add suffix –LF (e.g. MP4689DN–LF–Z)
PACKAGE REFERENCE
ABSOLUTE MAXIMUM RATINGS (1)
Supply Voltage (VIN) ................... -0.3V to +100V
Switch Voltage (VSW) ............. -0.5V to VIN + 0.5V
BST to SW ..................................... -0.3V to +6V
All Other Pins ................................. -0.3V to +6V
Junction Temperature .............................. 150C
Continuous Power Dissipation (TA = +25°C) (2)
............................................................ 2.5W
Lead Temperature ................................... 260C
Storage Temperature ............... -65°C to +150C
Recommended Operating Conditions (3)
Supply Voltage VIN .......................... 4.5V to 95V
EN and DIM Voltages .......................... 0V to 5V
Operating Junction Temp.(TJ) .. -40C to +125C
Thermal Resistance (4) θJA θJC
SOIC-8 EP .............................. 50 ...... 10 ... C/W
Notes:
1) Exceeding these ratings may damage the device.
2) The maximum allowable power dissipation is a function of the
maximum junction temperature TJ(MAX), the junction-to-
ambient thermal resistance θJA, and the ambient temperature
TA. The maximum allowable continuous power dissipation at
any ambient temperature is calculated by PD(MAX)=(TJ(MAX)-
TA)/θJA. Exceeding the maximum allowable power dissipation
will cause excessive die temperature, and the regulator will go
into thermal shutdown. Internal thermal shutdown circuitry
protects the device from permanent damage.
3) The device is not guaranteed to function outside of its
operating conditions.
4) Measured on JESD51-7 4-layer board.
MP4689 – 100V INPUT, 1A HIGH POWER LED DRIVER
MP4689 Rev. 1.01 www.MonolithicPower.com 3
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ELECTRICAL CHARACTERISTICS
VIN = 60V, TA= +25C, unless otherwise noted.
Specifications over temperature are guaranteed by design and characterization.
Parameter
Condition
Min
Typ
Max
Units
VIN UVLO Threshold
3.6
4.0
4.35
V
VIN UVLO Hysteresis
0.4
V
Shutdown Supply Current
VEN = 0V
2
5
µA
Quiescent Supply Current
No load, VFB = 250mV
170
240
µA
Upper Switch On Resistance (5)
VBST – VSW = 5V
500
mΩ
Upper Switch Leakage Current
VEN = 0V, VSW = 0V
0.01
1
µA
Current Limit
VFB = 0.15V
1.7
2.5
A
EN Up Threshold
1.4
1.55
1.7
V
EN Threshold Hysteresis
320
mV
EN Input Current
VEN =5V
0.01
1
µA
EN Sinking Current
VEN =2V
2
3
µA
DIM Up Threshold
0.8
1.15
1.5
V
DIM Threshold Hysteresis
300
mV
DIM Input Current
VDIM =5V or 0V
-1
1
µA
DIM On Propagation Delay
VFB=0V, VDIM Rising edge to
VSW Rising Edge
50
ns
DIM Off Propagation Delay
VFB=0V, VDIM Falling edge to
VSW Falling Edge
50
ns
Feedback Voltage Threshold High (5)
4.5V < VIN < 95V, VFB rising
from 0V until VSW < 30V
209
215
221
mV
Feedback Voltage Threshold Low (5)
4.5V < VIN < 95V, VFB falling
from 0.25V until VSW > 30V
179
185
191
mV
FB Pin Input Current
VFB=5V or 0V
-300
300
nA
FB Propagation Delay to Output
High
Falling edge of VFB from
0.25V to 0V to VSW rising
edge
100
ns
FB Propagation Delay to Output
High
Rising edge of VFB from 0V
to
0.25V to VSW falling edge
100
ns
Thermal Shutdown
Hysteresis = 20C
150
C
Note:
5) Guaranteed by design.
MP4689 – 100V INPUT, 1A HIGH POWER LED DRIVER
MP4689 Rev. 1.01 www.MonolithicPower.com 4
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PIN FUNCTIONS
SOIC8E
Pin #
Name
Description
1
FB
Feedback. This is the input to hysteretic comparators. An external current sensing resistor is
connected in series with the LEDs to GND. The feedback voltage is connected to this pin
and is regulated at +200mV with 15% current ripple.
2
N/C
Not connected
3
VIN
Input Supply. This supplies power to all the internal control circuitry, both BS regulators and
the high-side switch. A decoupling capacitor to ground must be placed close to this pin to
minimize switching spikes.
4
BST
Bootstrap. This is the positive power supply for the internal floating high-side MOSFET
driver. Connect a bypass capacitor between this pin and SW pin.
5
SW
Switch Node. This is the output from the high-side switch. A low VF Schottky rectifier to
ground is required. The rectifier must be close to the SW pins to reduce switching spikes.
6
DIM
PWM Dimming Input. Pulling this pin below the specified threshold for dimming off. Pulling it
up above the specified threshold for dimming on. If there is no need for dimming function,
connect DIM and EN pins together.
7
EN
Enable Input. Pulling this pin below the specified threshold shuts the chip down. Pulling it up
above the specified threshold or leaving it floating enables the chip.
8
GND,
Exposed
pad
Ground. It should be connected as close as possible to the output capacitor avoiding the
high current switch paths. Connect exposed pad to GND plane for optimal thermal
performance.
MP4689 – 100V INPUT, 1A HIGH POWER LED DRIVER
MP4689 Rev. 1.01 www.MonolithicPower.com 5
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BLOCK DIAGRAM
Figure 1—Function Block Diagram
MP4689 – 100V INPUT, 1A HIGH POWER LED DRIVER
MP4689 Rev. 1.01 www.MonolithicPower.com 6
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TYPICAL PERFORMANCE CHARACTERISTICS
L=47μH, 1 LED Load, TA=25 oC, unless otherwise noted.
MP4689 – 100V INPUT, 1A HIGH POWER LED DRIVER
MP4689 Rev. 1.01 www.MonolithicPower.com 7
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OPERATION
Hysteresis Current Control with Adaptive
Threshold Adjustment
MP4689 operates in a hysteresis current control
mode to regulate the LED current accurately.
FB pin is the sensed voltage of LED current
across the sensing resistor. The power
MOSFET is turned on and remains on until FB
pin rises to 215mV. The power MOSFET is
turned off and remains off until FB pin falls to
185mV. The two thresholds of 215mV and
185mV are adaptive adjusted to compensate all
the circuit delays so that the LED current is
regulated very accurately with 200mV average
value at FB pin.
Enable Control
The MP4689 has a dedicated enable control pin
(EN) with the positive logic. Its falling threshold
is a precision 1.2V, and its rising threshold is
1.5V (300mV higher).
When floating, EN is pulled up to about 3.0V by
an internal 1µA current source so it is enabled.
To pull it down, over 1µA current capability is
needed.
Floating Driver and Bootstrap Charging
The floating power MOSFET driver is powered
by an external bootstrap capacitor. This floating
driver has its own UVLO protection. This
UVLO’s rising threshold is 2.2V with a threshold
of 150mV.
The bootstrap capacitor is charged and
regulated to about 5V by the dedicated internal
bootstrap regulator.
In case the internal circuit does not have
sufficient voltage and the bootstrap capacitor is
not well charged, extra external circuitry can be
used to ensure the bootstrap voltage is in the
normal operational region. Refer to External
Bootstrap Diode in Application section.
Under-Voltage Lockout (UVLO)
Under-voltage lockout (UVLO) is implemented
to protect the chip from operating at insufficient
supply voltage. The UVLO rising threshold is
about 4.0V while its falling threshold is a
consistent 3.65V.
Thermal Shutdown
Thermal shutdown is implemented to prevent
the chip from operating at exceedingly high
temperatures. When the silicon die temperature
is higher than its upper threshold, it shuts down
the whole chip. When the temperature is lower
than its lower threshold, the chip is enabled
again.
LED Short Protection
The LED current is well regulated with FB pin
voltage at 200mV. As long as the LED sensing
resistor is not failed, the output current is within
limitation. If the LED sensing resistor is failed or
the output is shorted to GND directly, the FB pin
voltage is low even the power MOSFET is
turned on. The power MOSFET will be shut off
if such failure time is longer than 10us. MP4689
will retry the operation after about 300μs delay.
The power MOSFET current is also accurately
sensed via a current sense MOSFET. If the
current is over 2.5A, the IC is shut down. This
offers extra protection under output short
conditions.
MP4689 – 100V INPUT, 1A HIGH POWER LED DRIVER
MP4689 Rev. 1.01 www.MonolithicPower.com 8
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APPLICATION INFORMATION
COMPONENT SELECTION
Setting the LED Current
The LED current ILED is set using a sensing
resistor RFB, which is in series with the LEDs
and connected to GND. The voltage on the
sensing resistor RFB is connected to FB pin.
FB
LED FB
V
IR
For example, for a 700mA LED current, RFB is
287mΩ.
Inductor Selection and Frequency Setting
The inductor LO is required to supply a constant
current to the LED. The inductor value is related
to the switching frequency fs setting:
OUT IN OUT
s8
IN IN LED
V (V V )
fV (8 10 V L 15% I )

Where, VIN is the input voltage, VOUT is the
output voltage to drive the LEDs. A larger value
inductor will result in smaller switching
frequency.
The peak inductor current is about:
8IN
LP LED LED
4 10 V
I I ( 1.075)
LI

Choose an inductor that will not saturate under
the maximum inductor peak current and the
switching frequency under 2MHz.
Output Rectifier Diode
The output rectifier diode supplies the current to
the inductor when the high-side switch is off. To
reduce losses due to the diode forward voltage
and recovery times, use a Schottky diode.
The RMS current through the diode is about:
OUT
D LED IN
V
I I 1 V
Choose a diode whose maximum reverse
voltage rating is greater than the maximum
input voltage, and whose current rating is
greater than the maximum diode current.
Input Capacitor CIN
The input current to the step-down converter is
discontinuous, therefore a capacitor is required
to supply the AC current to the step-down
converter while maintaining the DC input
voltage. Use low ESR capacitors for the best
performance especially under high switching
frequency applications.
The RMS current through the input capacitor is
about:
OUT
D LED IN
V
II V

’
With low ESR capacitors, the input voltage
ripple can be estimated by:
OUT OUT
LED
IN s IN IN IN
VV
I
V1
f C V V



Choose the input capacitor with enough RMS
current rating and enough capacitance for small
input voltage ripple.
When electrolytic or tantalum capacitors are
applied, a small, high quality ceramic capacitor,
i.e. 0.1μF, should be placed as close to the IC
as possible.
Output Capacitor COUT
The output capacitor (COUT) is not necessary for
MP4689. The LED current ripple (peak-to-peak
value) is about 15% of the LED DC current.
Output capacitor can be used to further reduce
the LED current ripple. Low ESR capacitors are
preferred to keep the output voltage ripple low
so that the AC ripple current through the LEDs
is small. The output voltage ripple can be
estimated by:
OUT OUT
OUT ESR
S O IN S OUT
VV 1
V 1 R
f L V 8 f C






Where RESR is the equivalent series resistance
(ESR) value of the output capacitor.
MP4689 – 100V INPUT, 1A HIGH POWER LED DRIVER
MP4689 Rev. 1.01 www.MonolithicPower.com 9
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External Bootstrap Diode
An external bootstrap diode may enhance the
efficiency of the LED driver. In below cases, an
external BST diode is recommended from the
5V to BST pin:
There is a 5V rail available in the system;
VIN is no greater than 5V;
VOUT is between 3.3V and 5V;
This diode is also recommended for high duty
cycle operation (when VOUT/VIN>65%) and very
high frequency (over 1.5MHz) applications.
The bootstrap diode can be a low cost one
such as IN4148 or BAT54.
Figure 2—External Bootstrap Diode
Layout Consideration
It is essential to place the input decoupling
capacitor, catch diode and the MP4689 (VIN
pin, SW pin and PGND) as close as possible,
with traces that are very short and fairly wide.
This can help to greatly reduce the voltage
spike on SW node, and lower the EMI noise
level as well.
Try to run the feedback trace as far from the
inductor and noisy power traces as possible. It
is often a good idea to run the feedback trace
on the side of the PCB opposite of the inductor
with a ground plane separating the two.
To help to improve the thermal conduction, a
grid of thermal vias can be created right under
the exposed pad. It is recommended that they
be small (15mil barrel diameter) so that the hole
is essentially filled up during the plating
process, thus aiding conduction to the other
side. Too large a hole can cause ‘solder
wicking’ problems during the reflow soldering
process. The pitch (distance between the
centers) of several such thermal vias in an area
is typically 40mil.
MP4689 – 100V INPUT, 1A HIGH POWER LED DRIVER
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.
MP4689 Rev. 1.01 www.MonolithicPower.com 10
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2018 MPS. All Rights Reserved.
PACKAGE INFORMATION
SOIC-8 EP