HV9910B
Universal High Brightness LED Driver
Features
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Switch mode controller for single switch LED drivers
Enhanced drop-in replacement to the HV9910
Open loop peak current controller
Internal 8.0V to 450V linear regulator
Constant frequency or constant off-time operation
Linear and PWM dimming capability
Requires few external components for operation
General Description
The HV9910B is an open loop current mode control LED driver
IC. The HV9910B can be programmed to operate in either a
constant frequency or constant off-time mode. It includes an
8 – 450V linear regulator which allows it to work from a wide
range of input voltages without the need for an external low
voltage supply. The HV9910B includes a PWM dimming input
that can accept an external control signal with a duty ratio of 0
– 100% and a frequency of up to a few kilohertz. It also includes
a 0 – 250mV linear dimming input which can be used for linear
dimming of the LED current.
The HV9910B is ideally suited for buck LED drivers. Since
the HV9910B operates in open loop current mode control, the
controller achieves good output current regulation without the
need for any loop compensation. PWM dimming response is
limited only by the rate of rise and fall of the inductor current,
enabling very fast rise and fall times. The HV9910B requires
only three external components (apart from the power stage) to
produce a controlled LED current making it an ideal solution for
low cost LED drivers.
Applications
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DC/DC or AC/DC LED driver applications
RGB backlighting LED driver
Back lighting of flat panel displays
General purpose constant current source
Signage and decorative LED lighting
Chargers
Typical Application Circuit
C
IN
D1
C
DD
VDD
L1
VIN
C
O
HV9910B
LD
PWMD
RT
GATE
CS
GND
R
CS
Q1
R
T
HV9910B
Ordering Information
Device
HV9910B
Package Options
8-Lead SO
HV9910BLG-G
16-Lead SO
HV9910BNG-G
Pin Description
1
2
3
4
1
2
3
VIN
NC
NC
CS
GND
NC
NC
GATE
NC
NC
RT
LD
VDD
NC
NC
PWMD
16
15
14
13
12
11
10
9
-G indicates package is RoHS compliant (‘Green’)
VIN
CS
GND
GATE
RT
LD
VDD
PWMD
8
7
6
5
5
6
7
8
Absolute Maximum Ratings
Parameter
V
IN
to GND
CS, LD, PWMD, GATE, RT
V
DD
to GND
Junction Temperature Range
Storage Temperature Range
Continuous Power Dissipation
(T
A
= +25°C)
8-Lead SO
16-Lead SO
Value
-0.5V to +470V
-0.3V to (V
DD
+ 0.3V)
12V
-40°C to +150°C
-65°C to +150°C
4
8-Lead SO (LG)
16-Lead SO (NG)
Product Marking
YWW
9910B
LLLL
Y = Last Digit of Year Sealed
WW = Week Sealed
L = Lot Number
= “Green” Packaging
8-Lead SO (LG)
830mW
1300mW
Top Marking
HV9910BNG
YWW
LLLLLLLL
Stresses beyond those listed under “Absolute Maximum Ratings” may
cause permanent damage to the device. These are stress ratings only,
and functional operation of the device at these or any other conditions
beyond those indicated in the operational sections of the specifications is
not implied. Exposure to absolute maximum rating conditions for extended
periods may affect device reliability.
Bottom Marking
CCCCCCCCC AAA
Y = Last Digit of Year Sealed
WW = Week Sealed
L = Lot Number
C = Country of Origin*
A = Assembler ID*
= “Green” Packaging
*May be part of top marking
Thermal Impedence
8-Lead SO (LG)
16-Lead SO (NG)
128
O
C/W
82
O
C/W
16-Lead SO (NG)
(The * denotes specifications which apply over the full operating ambient temperature range of -40°C<T
A
<125°C.
Otherwise specifications are at T
A
= 25°C. V
IN
= 12V, unless otherwise noted. All Typical Numbers are at T
A
= 25°C )
Electrical Characteristics
Symbol
Description
Min
Typ
Max
Units
Conditions
Input
V
INDC
I
INSD
Input DC supply voltage range
(1)
Shut-Down mode supply current
*
-
8.0
-
-
0.5
450
1
V
mA
DC input voltage
Pin PWMD to GND
Internal Regulator
V
DD
Internally regulated voltage
-
7.25
7.5
7.75
V
V
IN
= 8V, I
DD(ext)(†)
= 0, 500pF at
GATE; R
T
= 226kΩ, PWMD = V
DD
V
IN
= 8 - 450V, I
DD(ext)
= 0,
500pF at GATE; R
T
= 226kΩ,
PWMD = V
DD
ΔV
DD, line
Line Regulation of V
DD
-
0
-
1
V
2
HV9910B
Internal Regulator
(cont.)
Symbol
ΔV
DD, load
UVLO
∆UVLO
I
IN,MAX
Description
Load Regulation of V
DD
V
DD
undervoltage lockout threshold
V
DD
undervoltage lockout hysteresis
Current that the regulator can
supply before IC goes into UVLO
-
*
#
#
Min
0
6.45
-
5
Typ
-
6.7
500
-
Max
100
6.95
-
-
Units
mV
V
mV
mA
Conditions
I
DD(ext)
= 0 – 1mA, 500pF at GATE;
R
T
= 226kΩ, PWMD = V
DD
V
IN
rising
V
IN
falling
V
IN
= 8V
PWM Dimming
V
EN(lo)
V
EN(hi)
R
EN
Pin PWMD input low voltage
Pin PWMD input high voltage
Pin PWMD pull-down resistance
at PWMD
*
*
-
-
2.4
50
-
-
100
1.0
-
150
V
V
kΩ
V
IN
= 8V – 450V
V
IN
= 8V – 450V
V
PWMD
= 5.0V
Current Sense Comparator
V
CS,TH
V
OFFSET
T
BLANK
t
DELAY
Current sense pull-in threshold
voltage
Offset voltage for LD comparator
Current sense blanking interval
Delay to output
-
*
*
-
225
213
-12
150
-
250
250
-
215
80
275
287
12
280
150
mV
mV
ns
ns
-40°C < T
A
< +85°C
T
A
< +125°C
---
---
V
LD
= V
DD
,
V
CS
= V
CS,TH
+ 50mV after T
BLANK
Oscillator
f
OSC
Oscillator frequency
-
-
20
80
25
100
30
120
kHz
R
T
= 1.00MΩ
R
T
= 226kΩ
V
GATE
= 0V
V
GATE
= V
DD
C
GATE
= 500pF
C
GATE
= 500pF
GATE Driver
I
SOURCE
I
SINK
t
RISE
t
FALL
(1)
(†)
*
#
Gate sourcing current
Gate sinking current
GATE output rise time
GATE output fall time
-
-
-
-
0.165
0.165
-
-
-
-
30
30
-
-
50
50
A
A
ns
ns
Also limited by package power dissipation limit, whichever is lower.
V
DD
load current external to the HV9910B
Specifications that apply over the full temperature range are guaranteed by design and characterization
Guaranteed by design
3
HV9910B
Pin Description
Function
VIN
VDD
GATE
GND
PWMD
Description
This pin is the input of an 8V – 450V linear regulator.
This is the power supply pin for all internal circuits.
It must be bypassed with a low ESR capacitor to GND (≥ 0.1μF).
This pin is the output gate driver for an external N-channel power MOSFET.
Ground return for all internal circuitry. This pin must be electrically connected to the ground of the power
train.
This is the PWM dimming input of the IC. When this pin is pulled to GND, the gate driver is turned off.
When the pin is pulled high, the gate driver operates normally.
This pin is the current sense pin used to sense the FET current by means of an external sense resistor.
When this pin exceeds the lower of either the internal 250mV or the voltage at the LD pin, the gate output
goes low.
This pin is the linear dimming input and sets the current sense threshold as long as the voltage at the pin
is less than 250mV (typ).
This pin sets the oscillator frequency. When a resistor is connected between RT and GND, the HV9910B
operates in constant frequency mode. When the resistor is connected between RT and GATE, the IC
operates in constant off-time mode.
No connection
CS
LD
RT
NC
Block Diagram
VIN
Regulator
POR
VDD
LD
-
+
Blanking
250mV
+
-
Oscillator
R Q
S
GATE
CS
GND
RT
PWMD
4
HV9910B
Application Information
The HV9910B is optimized to drive buck LED drivers using
open-loop peak current mode control. This method of control
enables fairly accurate LED current control without the need
for high side current sensing or the design of any closed loop
controllers. The IC uses very few external components and
enables both Linear and PWM dimming of the LED current.
A resistor connected to the RT pin programs the frequency
of operation (or the off-time). The oscillator produces pulses
at regular intervals. These pulses set the SR flip-flop in the
HV9910B which causes the gate driver to turn on. The same
pulses also start the blanking timer which inhibits the reset
input of the SR flip flop and prevent false turn-offs due to the
turn-on spike. When the FET turns on, the current through
the inductor starts ramping up. This current flows through
the external sense resistor R
CS
and produces a ramp voltage
at the CS pin. The comparators are constantly comparing
the CS pin voltage to both the voltage at the LD pin and
the internal 250mV. Once the blanking timer is complete, the
output of these comparators is allowed to reset the flip flop.
When the output of either one of the two comparators goes
high, the flip flop is reset and the gate output goes low. The
gate goes low until the SR flip flop is set by the oscillator.
Assuming a 30% ripple in the inductor, the current sense
resistor R
CS
can be set using:
R
CS
=
0.25V (or V
LD
)
1.15 I
LED
(A)
●
7.5V at the VDD pin. This voltage is used to power the IC
and any external resistor dividers needed to control the IC.
The VDD pin must be bypassed by a low ESR capacitor to
provide a low impedance path for the high frequency current
of the output gate driver.
The HV9910B can also be operated by supplying a voltage
at the VDD pin greater than the internally regulated voltage.
This will turn off the internal linear regulator of the IC and the
HV9910B will operate directly off the voltage supplied at the
VDD pin. Please note that this external voltage at the VDD
pin should not exceed 12V.
Although the VIN pin of the HV9910B is rated up to 450V,
the actual maximum voltage that can be applied is limited
by the power dissipation in the IC. For example, if an 8-pin
SOIC (junction to ambient thermal resistance R
θ,j-a
= 128°C/
W) HV9910B draws about I
IN
= 2mA from the VIN pin, and
has a maximum allowable temperature rise of the junction
temperature limited to about ΔT = 100°C, the maximum volt-
age at the VIN pin would be:
Constant frequency peak current mode control has an in-
herent disadvantage – at duty cycles greater than 0.5, the
control scheme goes into subharmonic oscillations. To pre-
vent this, an artificial slope is typically added to the current
sense waveform. This slope compensation scheme will af-
fect the accuracy of the LED current in the present form.
However, a constant off-time peak current control scheme
does not have this problem and can easily operate at duty
cycles greater then 0.5 and also gives inherent input volt-
age rejection making the LED current almost insensitive to
input voltage variations. But, it leads to variable frequency
operation and the frequency range depends greatly on the
input and output voltage variation. HV9910B makes it easy
to switch between the two modes of operation by changing
one connection (see oscillator section).
In these cases, to operate the HV9910B from higher input
voltages, a Zener diode can be added in series with the VIN
pin to divert some of the power loss from the HV9910B to
the Zener diode. In the above example, using a 100V zener
diode will allow the circuit to easily work up to 450V.
The input current drawn from the VIN pin is a sum of the
1.0mA current drawn by the internal circuit and the current
drawn by the gate driver (which in turn depends on the switch-
ing frequency and the gate charge of the external FET).
I
IN
≈ 1.0mA + Q
G
• f
S
In the above equation, f
S
is the switching frequency and Q
G
is the gate charge of the external FET (which can be ob-
tained from the datasheet of the FET).
Input Voltage Regulator
The HV9910B can be powered directly from its VIN pin and
can work from 8-450VDC at its VIN pin. When a voltage is
applied at the VIN pin, the HV9910B maintains a constant
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