2015 Microchip Technology Inc.
20005462B-page 1
Features
• Hysteretic control with high-side current sensing
• Wide input-voltage range: 4.5 to 40V
• >90% Efficiency
• Typical ±5% LED current accuracy
• Up to 2.0MHz switching frequency
• Adjustable constant LED current
• Analog or PWM control signal for PWM dimming
• Over-temperature protection
• -40ºC to +125ºC operating temperature range
Applications
• Low-voltage industrial and architectural lighting
• General purpose constant current source
• Signage and decorative LED lighting
• Indicator and emergency lighting
Description
HV9919B is a Pulse-Width Modulation (PWM) control-
ler IC designed to drive high-brightness LEDs using a
buck topology. It operates from an input voltage of 4.5
to 40VDC and employs hysteretic control, with a high-
side current sense resistor, to set the constant output
current.
Set the operating frequency range by selecting the
proper inductor. Operation at high switching frequency
is possible since the hysteretic control maintains accu-
racy even at high frequencies. This permits the use of
small inductors and capacitors, minimizing space and
cost in the overall system.
LED brightness control is achieved with PWM dimming
from an analog or PWM input signal. Unique PWM cir-
cuitry allows true constant color with a high dimming
range. The dimming frequency is programmed using a
single external capacitor.
HV9919B comes in a small, 8-Lead DFN package and
is ideal for industrial and general lighting applications.
Package Type
See
Table 2-1
for pin information
8-Lead DFN
8
7
6
5
1
2
3
4
CS
VIN
RAMP
ADIM
GATE
GND
VDD
DIM
GND
HV9919B
Hysteretic, Buck, High Brightness LED Driver
with High-Side Current Sensing
HV9919B
20005462B-page 2
2015 Microchip Technology Inc.
Block Diagram
Typical Application Circuit
CURRENT
SENSE
COMPARATOR
UVLO
COMPARATOR
GATE
DRIVER
VIN
VDD
CS
RAMP
ADIM
GND
DIM
GATE
HV9919B
PWM RAMP
0.1~1.9V
-
+
+
-
BANDGAP
REF
+
-
REGULATOR
C
IN
0 - 2.0V
HV9919B
VIN
VDD
GATE
GND
CS
RAMP
ADIM
DIM
R
SENSE
L
2015 Microchip Technology Inc.
20005462B-page 3
HV9919B
1.0
ELECTRICAL CHARACTERISTICS
ABSOLUTE MAXIMUM RATINGS
†
V
IN
to GND .................................................................................................................................................-0.3V to +45V
V
DD
to GND...............................................................................................................................................-0.3V to +6.0V
GATE, RAMP, DIM, ADIM to GND .............................................................................................................-0.3V to +V
DD
CS to V
IN
...................................................................................................................................................-1.0V to +0.3V
Continuous total power dissipation (T
A
= 25.°C) ..................................................................................................... 1.6W
Operating temperature range................................................................................................................ -40°C to +125°C
Junction temperature ...........................................................................................................................................+150°C
Storage temperature range ................................................................................................................... -65°C to +150°C
† Notice: Stresses above those listed under “Maximum Ratings” may cause permanent damage to the device. This is
a stress rating only and functional operation of the device at those or any other conditions above those indicated in the
operational listings of this specification is not implied. Exposure to maximum rating conditions for extended periods
may affect device reliability.
TABLE 1-1:
ELECTRICAL CHARACTERISTICS (SHEET 1 OF 2)
Electrical Specifications: V
IN
=12V, V
DIM
= V
DD
, V
RAMP
= GND, C
VDD
= 1.0 µF, R
CS
= 0.5Ω,
T
A
= T
J
= -40°C to +125°C, unless otherwise noted. (
Note 1
)
Parameter
Symbol
Min
Typ
Max
Units Conditions
Input DC supply voltage range
V
IN
4.5
-
40
V
DC input voltage
Internally regulated voltage
V
DD
4.5
-
5.5
V
V
IN
= 6.0 to 40V
Supply current
I
IN
-
-
1.5
mA
GATE open
Shutdown supply current
I
IN, SDN
-
-
900
µA
DIM<
0.7V
Current limit
I
IN, LIM
-
11
-
mA
V
IN
= 4.5V, V
DD
= 0V
-
5.5
-
V
IN
= 4.5V, V
DD
= 4.0V
Switching frequency
f
SW
-
-
2.0
MHz
–
V
DD
Undervoltage lockout thresh-
old
UVLO
-
-
4.5
V
V
DD
rising
V
DD
Undervoltage lockout hysteresis
∆UVLO
-
500
-
mV
V
DD
falling
Sense Comparator
Sense voltage threshold high
V
CS(HI)
-
230
-
mV
(V
IN
- V
CS
) rising
Sense voltage threshold low
V
CS(LO)
-
170
-
mV
(V
IN
- V
CS
) falling
Average sense voltage
V
CS(AVG)
186
200
214
mV
V
CS(AVG)
= 0.5(V
CS(HI)
+ V
CS(LO)
)
Propagation delay to output high
t
DPDH
-
70
-
ns
Falling edge of
(V
IN
- V
CS
) = V
RS(LO)
- 70mV
Propagation delay to output low
t
DPDL
-
70
-
ns
Rising edge of
(V
IN
- V
CS
) = V
RS(HI)
+ 70mV
Current-sense input current
I
CS
-
-
1.0
µA
(V
IN
- V
CS
) = 200mV
Current-sense threshold hysteresis
V
CS(HYS)
15
56
98
mV
V
CS(HYS)
= V
CS(HI)
- V
CS(LO)
DIM Input
Pin DIM input high voltage
V
IH
2.2
-
-
V
–
Pin DIM input low voltage
V
IL
-
-
0.7
V
–
Turn-on time
t
ON
-
100
-
ns
DIM rising edge to
V
GATE
= 0.5 x V
DD
, C
GATE
= 2.0nF
Turn-off time
t
OFF
-
100
-
ns
DIM falling edge to
V
GATE
= 0.5 x V
DD
, C
GATE
=2.0nF
HV9919B
20005462B-page 4
2015 Microchip Technology Inc.
Note 1: Specification is obtained by characterization and is 100% tested at T
A
= 25°C.
2: Specification is obtained by characterization and not 100% tested
GATE Driver
GATE current, source
I
GATE
0.3
0.5
-
A
V
GATE
= GND, (
Note 2
)
GATE current, sink
0.7
1.0
-
A
V
GATE
= V
DD
, (
Note 2
)
GATE output rise time
T
RISE
-
40
55
ns
C
GATE
= 2.0nF
GATE output fall time
T
FALL
-
17
25
ns
C
GATE
= 2.0nF
GATE high output voltage
V
GATE(HI)
V
DD
-0.5
-
-
V
I
GATE
= 10mA
GATE low output voltage
V
GATE(LO)
-
-
0.5
V
I
GATE
= -10mA
Over-Temperature Protection
Over temperature trip limit
T
OT
128
140
-
ºC
(
Note 2
)
Temperature hysteresis
∆T
HYST
-
60
-
ºC
(
Note 2
)
Analog Control of PWM Dimming
Dimming frequency
f
RAMP
114
-
308
Hz
C
RAMP
= 47nF
529
-
1380
C
RAMP
= 10nF
RAMP threshold, Low
V
LOW
-
0.1
-
V
–
RAMP threshold, High
V
HIGH
1.8
-
2.1
V
–
ADIM offset voltage
V
OS
-35
-
+35
mV
–
TEMPERATURE SPECIFICATIONS
Electrical Specifications: Unless otherwise specified, for all specifications T
A
=T
J
= +25°C
Parameter
Symbol
Min
Typ
Max
Units Conditions
Temperature Ranges
Operating Temperature
-40
125
°C
Storage Temperature
-65
–
150
°C
Package Thermal Resistances
Thermal Resistance, DFN
θ
ja
–
60
–
°C/W
Mounted on FR-4 board,
25 mm x 25 mm x 1.57 mm
TABLE 1-1:
ELECTRICAL CHARACTERISTICS (SHEET 2 OF 2)
Electrical Specifications: V
IN
=12V, V
DIM
= V
DD
, V
RAMP
= GND, C
VDD
= 1.0 µF, R
CS
= 0.5Ω,
T
A
= T
J
= -40°C to +125°C, unless otherwise noted. (
Note 1
)
Parameter
Symbol
Min
Typ
Max
Units Conditions
2015 Microchip Technology Inc.
20005462B-page 5
HV9919B
2.0
PIN DESCRIPTION
The locations of the pins are listed in
Features
.
TABLE 2-1:
PIN DESCRIPTION
Pin #
Symbol
Description
1
CS
Current sense input. Senses LED
string current.
2
VIN
Input voltage 4.5 to 40V DC.
3
RAMP
Analog PWM dimming ramp output.
4
ADIM
Analog 0~2.0V signal input for analog
control of PWM dimming.
5
DIM
PWM signal input.
6
VDD
Internally regulated supply voltage.
Connect a capacitor from V
DD
to
ground.
7
GND
Device ground.
8
GATE
Drives gate of external MOSFET.
TAB
GND
Must be wired to pin 7 on PCB.
HV9919B
20005462B-page 6
2015 Microchip Technology Inc.
3.0
APPLICATION INFORMATION
HV9919B is a step-down, constant current, High-
Brightness LED (HB LED) driver. The device operates
from a 4.5 to 40V input voltage range and provides the
gate drive output to an external N-channel MOSFET.
A high-side, current-sense resistor sets the output cur-
rent and a dedicated PWM Dimming Input (DIM) allows
for a wide range of dimming duty ratios. The PWM dim-
ming could also be achieved by applying a DC voltage
between 0 and 2.0V to the Analog Dimming Input
(ADIM). In this case, the dimming frequency can be
programmed using a single capacitor at the RAMP pin.
The high-side current setting and sensing scheme min-
imizes the number of external components while deliv-
ering LED current with a ±8% accuracy, using a 1%
sense resistor.
3.1
Undervoltage Lockout (UVLO)
HV9919B includes a 3.7V Under-Voltage lockout
(UVLO) with 500mV hysteresis. When V
DD
falls below
3.7V, GATE goes low, turning off the external N-channel
MOSFET. GATE goes high once V
DD
is 4.5V or higher.
3.2
5.0V Regulator
V
DD
is the output of a 5.0V regulator capable of sourc-
ing 5.0 mA. Bypass V
DD
to GND with a 1.0μF capacitor.
3.3
DIM Input
HV9919B allows dimming with a PWM signal at the
DIM input. A logic level below 0.7V at DIM forces the
GATE output low, turning off the LED current. To turn
the LED current on, the logic level at DIM must be at
least 2.2V.
3.4
ADIM and RAMP Inputs
The PWM dimming scheme can be also implemented
by applying an analog control signal to ADIM pin. If an
analog control signal of 0 – 2.0V is applied to ADIM, the
device compares this analog input to a voltage ramp to
pulse-width-modulate the LED current. Connecting an
external capacitor to RAMP programs the PWM dim-
ming ramp frequency.
DIM and ADIM inputs can be used simultaneously. In
such a case, f
PWM(MAX)
must be selected lower than
the frequency of the dimming signal at DIM. The
smaller dimming duty cycle of ADIM and DIM will deter-
mine the GATE signal.
When the analog control of PWM dimming feature is
not used, RAMP must be wired to GND, and ADIM
should be connected to V
DD
.
One possible application of the ADIM feature of
HV9919B may include protection of the LED load from
over-temperature by connecting an NTC thermistor at
ADIM, as shown in
Figure 3-1
FIGURE 3-1:
NTC Thermistor at ADIM
3.5
Setting LED Current with External
Resistor R
SENSE
The output current in the LED is determined by the
external current sense resistor (R
SENSE
) connected
between V
IN
and CS. Disregarding the effect of the
propagation delays, the sense resistor can be calcu-
lated as:
3.6
Selecting Buck Inductor L
HV9919B regulates the LED output current using a
comparator with hysteresis, see
Figure 3-2
. As the cur-
rent through the inductor ramps up and the voltage
across the sense resistor reaches the upper threshold,
the voltage at GATE goes low, turning off the external
MOSFET. The MOSFET turns on again when the
inductor current ramps down through the freewheeling
diode, until the voltage across the sense resistor
equals the lower threshold. Use the following equation
to determine the inductor value for a desired value of
operating frequency f
S
:
f
PWM
1
C
RAMP
120K
------------------------------------------
=
NTC
VDD
ADIM
GND
HV9919B
R
SENSE
1
2
---
V
CS HI
V
CS LO
+
I
LED
----------------------------------------------------
200mV
I
LED
------------------
=
L
V
IN
V
OUT
–
V
OUT
f
S
V
IN
I
O
--------------------------------------------------
V
IN
V
OUT
–
t
DPDL
I
O
----------------------------------------------
–
=
V
OUT
t
DPDH
I
O
------------------------------
–
2015 Microchip Technology Inc.
20005462B-page 7
HV9919B
Where:
and t
DPDL
, t
DPDH
are the propagation delays. The cur-
rent ripple ∆I in the inductor L is greater than ∆I
O
.
This ripple can be calculated from the following equa-
tion:
For the purpose of the proper inductor selection, note
that the maximum switching frequency occurs at the
highest V
IN
and V
OUT
= V
IN
/2.
FIGURE 3-2:
Regulating LED output
3.7
MOSFET Selection
MOSFET selection is based on the maximum input
operating voltage V
IN
, output current I
LED
, and operat-
ing switching frequency. Choose a logic-level MOSFET
that has a higher breakdown voltage than the maxi-
mum operation voltage, low R
DS(ON)
, and low total gate
charge for better efficiency.
3.8
Freewheeling Diode Selection
The forward voltage of the freewheeling diode should
be as low as possible for better efficiency. A Schottky
diode is a good choice as long as the breakdown volt-
age is high enough to withstand the maximum operat-
ing voltage. The forward-current rating of the diode
must be at least equal to the maximum LED current.
3.9
LED Current Ripple
The LED current ripple is equal to the inductor-current
ripple. In cases when a lower LED current ripple is
needed, a capacitor can be placed across the LED ter-
minals.
3.10
PCB Layout Guidelines
Careful PCB layout is critical to achieve low switching
losses and stable operation. Use a multilayer board
whenever possible for better noise immunity. Minimize
ground noise by connecting high-current ground
returns, the input bypass capacitor ground lead, and
the output filter ground lead to a single point (star
ground configuration). The fast di/dt loop is formed by
the input capacitor C
IN
, the free-wheeling diode and the
MOSFET. To minimize noise interaction, this loop area
should be as small as possible. Place R
SENSE
as close
as possible to the input filter and V
IN
. For better noise
immunity, a Kelvin connection is strongly recom-
mended between CS and R
SENSE
. Connect the
exposed tab of the IC to a large-area ground plane for
improved power dissipation.
I
O
V
CS HI
V
CS LO
–
R
SENSE
-----------------------------------------------
=
I
I
O
V
IN
V
OUT
–
t
DPDL
L
---------------------------------------------------
V
OUT
t
DPDH
L
------------------------------
+
+
=
t
t
I
LED
V
DIM
V
RS(HI)
R
SENSE
V
RS(LO)
R
SENSE
t
DPDL
t
DPDH
T
S
= 1/f
S
ΔI
ΔI
O
HV9919B
20005462B-page 8
2015 Microchip Technology Inc.
4.0
PACKAGING INFORMATION
4.1
Package Marking Information
Legend: XX...X
Product Code or Customer-specific information
Y
Year code (last digit of calendar year)
YY
Year code (last 2 digits of calendar year)
WW
Week code (week of January 1 is week ‘01’)
NNN
Alphanumeric traceability code
Pb-free JEDEC
®
designator for Matte Tin (Sn)
*
This package is Pb-free. The Pb-free JEDEC designator ( )
can be found on the outer packaging for this package.
Note:
In the event the full Microchip part number cannot be marked on one line, it will
be carried over to the next line, thus limiting the number of available
characters for product code or customer-specific information. Package may or
not include the corporate logo.
3
e
3
e
8-lead DFN
Example
NNN
YYWW
XXXX
343
1542
9919
2015 Microchip Technology Inc.
20005462B-page 9
HV9919B
Note: For the most current package drawings, see the Microchip Packaging Specification at www.microchip.com/packaging.
HV9919B
20005462B-page 10
2015 Microchip Technology Inc.
APPENDIX A: REVISION HISTORY
Revision A (November 2015)
• Updated file to Microchip format.
• Revised
Absolute Maximum Ratings
†
.
• Modified values and notes in
Table 1-1
.
• Added condition to
Temperature Specifications
.
• Changed value in
Section 3.2 “5.0V Regulator”
.
• Wording change in
Section 3.7 “MOSFET Selec-
tion”
.
• Minor text changes throughout.
Revision B (December 2015)
• Updated Revision History.