Supertex inc.
LED Driver with Average-Mode
Constant Current Control
Features
►
►
►
►
►
►
►
Fast average current control
Programmable constant off-time switching
Linear dimming input
PWM dimming input
Output short circuit protection with skip mode
Ambient operating temperature -40
O
C to +125
O
C
Pin-compatible with the HV9910B
HV9961
General Description
The HV9961 is an average current mode control LED driver
IC operating in a constant off-time mode. Unlike HV9910B,
this control IC does not produce a peak-to-average error, and
therefore greatly improves accuracy, line and load regulation
of the LED current without any need for loop compensation or
high-side current sensing. The output LED current accuracy
is ±3%.
The IC is equipped with a current limit comparator for hiccup-
mode output short circuit protection.
The HV9961 can be powered from an 8.0 - 450V supply.
A PWM dimming input is provided that accepts an external
control TTL compatible signal. The output current can be
programmed by an internal 275mV reference, or controlled
externally through a 0 - 1.5V dimming input.
HV9961 is pin-to-pin compatible with HV9910B and it can
be used as a drop-in replacement for many applications to
improve the LED current accuracy and regulation.
Applications
►
►
►
►
►
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DC/DC or AC/DC LED driver applications
LED backlight driver for LCD displays
General purpose constant current source
LED signage and displays
Architectural and decorative LED lighting
LED street lighting
Typical Application Circuit
8.0 - 450VDC
1
LED
Load
VIN
5
PWMD
GATE
4
6
VDD
HV9961
CS
2
RT
8
7
LD
R
T
R
CS
GND
3
Sets
LED
Current
Supertex inc.
●
1235 Bordeaux Drive, Sunnyvale, CA 94089
●
Tel: 408-222-8888
●
www.supertex.com
HV9961
Ordering Information
Package Options
Device
4.90x3.90mm body
1.75mm height (max)
1.27mm pitch
Pin Description
VIN
1
NC
2
NC
3
CS
4
VIN
1
CS
2
GND
3
GATE
4
8
RT
7
LD
6
VDD
5
PWMD
16
NC
15
NC
14
RT
13
LD
12
VDD
11
NC
10
NC
9
8-Lead SOIC
9.90x3.90mm body
1.75mm height (max)
1.27mm pitch
16-Lead SOIC
HV9961
HV9961LG-G
HV9961NG-G
GND
5
NC
6
NC
7
GATE
8
-G indicates package is RoHS compliant (‘Green’)
PWMD
8-Lead SOIC (LG)
16-Lead SOIC (NG)
Absolute Maximum Ratings
Parameter
V
IN
to GND
V
DD
to GND
CS, LD, PWMD, GATE, RT to GND
Junction temperature range
Storage temperature range
Continuous power dissipation
(T
A
= +25°C)
8-Lead SOIC
16-Lead SOIC
Value
-0.5V to +470V
12V
-0.3V to (V
DD
+0.3V)
-40°C to +150°C
-65°C to +150°C
650mW
1000mW
Product Marking
H9961
YWW
LLLL
Y = Last Digit of Year Sealed
WW = Week Sealed
L = Lot Number
= “Green” Packaging
Package may or may not include the following marks: Si or
8-Lead SOIC (LG)
Top Marking
YWW
HV9961NG
LLLLLLLL
Bottom Marking
CCCCCCCCC AAA
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.
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
Package may or may not include the following marks: Si or
Thermal Resistance
Package
8-Lead SOIC
16-Lead SOIC
θ
JA
128
O
C/W
82
O
C/W
16-Lead SOIC (NG)
Electrical Characteristics
(Specifications are at T
Sym
Description
Input DC supply voltage range
1
Shut-down mode supply current
*
*
A
= 25°C. V
IN
= 12V, V
LD
= V
DD
, PWMD = V
DD
unless otherwise noted))
Min
8.0
-
Typ
-
0.5
Max
450
1.0
Units
V
mA
Conditions
DC input voltage
Pin PWMD to GND
Input
V
INDC
I
INSD
Notes:
1. Also limited by package power dissipation limit, whichever is lower.
*
Denotes the specifications which apply over the full operating ambient temperature range of -40°C < T
A
< +125°C.
Supertex inc.
●
1235 Bordeaux Drive, Sunnyvale, CA 94089
●
Tel: 408-222-8888
●
www.supertex.com
2
HV9961
Electrical Characteristics
(Specifications are at T
Sym
Description
A
= 25°C. V
IN
= 12V, V
LD
= V
DD
, PWMD = V
DD
unless otherwise noted))
Min
Typ
Max
Units
Conditions
V
IN
= 8.0V, I
DD(ext)
= 0,
500pF at GATE; R
T
= 226kΩ
V
IN
= 8.0 - 450V, I
DD(ext)
= 0,
500pF at GATE; R
T
= 226kΩ
I
DD(ext)
= 0 - 1.0mA,
500pF at GATE; R
T
= 226kΩ
V
IN
rising
V
IN
falling
V
IN
= 8.0V, T
A
= 25
O
C
V
IN
= 8.0V, T
A
= 125
O
C
V
IN
= 8.0 - 450V
V
IN
= 8.0 - 450V
V
PWMD
= 5.0V
---
---
Offset = V
CS
- A
V(LD)
• V
LD
;
V
LD
= 1.2V
---
V
LD
falling
V
LD
rising
---
CS = V
CS
+30mV
Reduction in output LED current
may occur beyond this duty cycle
---
CS = V
CS
+30mV
---
CS = V
DD
Internal Regulator
V
DD
ΔV
DD, line
ΔV
DD, load
UVLO
∆UVLO
I
IN,MAX
Internally regulated voltage
Line regulation of V
DD
Load regulation of V
DD
V
DD
undervoltage lockout
threshold
V
DD
undervoltage lockout
hysteresis
Maximum input current
(limited by UVLO)
-
-
-
*
-
#
#
*
*
-
7.25
0
0
6.45
-
3.5
1.5
-
2.2
50
7.50
-
-
6.70
500
-
-
-
-
100
7.75
1.0
100
6.95
-
-
-
0.8
-
150
V
V
mV
V
mV
mA
PWM Dimming
V
EN(lo)
V
EN(hi)
R
EN
V
CS
A
V(LD)
AV
LD(OFFSET)
-
V
LD(OFF)
ΔV
LD(OFF)
T
BLANK
T
ON(min)
D
MAX
V
CS
T
DELAY
T
HICCUP
T
ON(min)
PWMD input low voltage
PWMD input high voltage
Internal pull-down resistance
at PWMD
Current sense reference voltage
LD-to-CS voltage ratio
LD-to-CS voltage offset
CS threshold temp regulation
LD input voltage, shutdown
LD input voltage, enable
Current sense blanking interval
Minimum on-time
Maximum steady-state duty
cycle
Hiccup threshold voltage
Current limit delay CS-to-GATE
Short circuit hiccup time
Minimum on-time (short circuit)
V
V
kΩ
Average Current Sense Logic
-
-
-
*
-
-
*
-
-
268
0.182
0
-
-
-
150
-
75
-
-
-
-
150
200
-
-
-
286
0.188
10
5.0
-
-
320
1000
-
mV
-
mV
mV
mV
mV
ns
ns
%
Short Circuit Protection
-
-
-
-
410
-
350
-
-
-
-
-
470
150
550
430
mV
ns
μs
ns
Notes:
*
Denotes the specifications which apply over the full operating ambient temperature range of -40°C < T
A
< +125°C.
# Guaranteed by design.
Supertex inc.
●
1235 Bordeaux Drive, Sunnyvale, CA 94089
●
Tel: 408-222-8888
●
www.supertex.com
3
HV9961
Electrical Characteristics
(Specifications are at T
Sym
Description
A
= 25°C. V
IN
= 12V, V
LD
= V
DD
, PWMD = V
DD
unless otherwise noted))
Min
Typ
Max
Units
Conditions
T
OFF
Timer
T
OFF
Off time
-
-
-
-
-
-
32
8.0
0.165
0.165
-
-
40
10
-
-
30
30
48
12
-
-
50
50
μs
R
T
= 1.00MΩ
R
T
= 226kΩ
V
GATE
= 0V, V
DD
= 7.5V
V
GATE
= V
DD
, V
DD
= 7.5V
C
GATE
= 500pF, V
DD
= 7.5V
C
GATE
= 500pF, V
DD
= 7.5V
GATE Driver
I
SOURCE
I
SINK
t
RISE
t
FALL
GATE sourcing current
GATE sinking current
GATE output rise time
GATE output fall time
A
A
ns
ns
Notes:
*
Denotes the specifications which apply over the full operating ambient temperature range of -40°C < T
A
< +125°C.
# Guaranteed by design.
Functional Block Diagram
VIN
Regulator
UVLO
0.15/0.20V
POR
VDD
LD
MIN (V
LD
• 0.185, 0.275V)
Auto-REF
Average Current
Control Logic
OUT
GATE
CS
L/E
Blanking
IN
PWMD
R Q
S Q
CLK
T
OFF
Timer
Current
Mirror
GND
0.44V
HV9961
400µs
i
RT
Supertex inc.
●
1235 Bordeaux Drive, Sunnyvale, CA 94089
●
Tel: 408-222-8888
●
www.supertex.com
4
HV9961
Application Information
General Description
Peak-current control (as in HV9910B) of a buck converter is
the most economical and simple way to regulate its output
current. However, it suffers accuracy and regulation prob-
lems that arise from the so-called peak-to-average current
error, contributed by the current ripple in the output inductor
and the propagation delay in the current sense compara-
tor. The full inductor current signal is unavailable for direct
sensing at the ground potential in a buck converter when
the control switch is referenced to the same ground poten-
tial because the control switch is only conducting for small
periods. While it is very simple to detect the peak current in
the switch, controlling the average inductor current is usu-
ally implemented by level translating the sense signal from
+V
IN
. Though this is practical for relatively low input voltage
V
IN
, this type of average-current control may become exces-
sively complex and expensive in the offline AC or other high-
voltage DC applications.
The HV9961 employs Supertex’ proprietary control scheme,
achieving fast and very accurate control of average current
in the buck inductor through sensing the switch current only.
No compensation of the current control loop is required. The
LED current response to PWMD input is similar to that of the
HV9910B. The inductor current ripple amplitude does not af-
fect this control scheme significantly, and therefore, the LED
current is independent of the variation in inductance, switch-
ing frequency or output voltage. Constant off-time control of
the buck converter is used for stability and to improve the
LED current regulation over a wide range of input voltages.
(Note that, unlike HV9910B, the HV9961 does not support
the constant-frequency mode of operation.)
feedback operates in a fast open-loop mode. No compensa-
tion is required. Output current is programmed simply as:
I
LED
=
0.275V
R
CS
(2)
when the voltage at the LD input V
LD
≥ 1.5V. Otherwise:
I
LED
=
V
LD
• 0.185
R
CS
(3)
The above equations are only valid for continuous conduc-
tion of the output inductor. It is a good practice to design the
inductor such that the switching ripple current in it is 30~40%
of its average peak-to-peak, full load, DC current. Hence,
the recommended inductance can be calculated as:
L
O
=
V
O(MAX)
• T
OFF
0.4 • I
O
(4)
The duty-cycle range of the current control feedback is lim-
ited to D ≤ 0.75. A reduction in the LED current may occur
when the LED string voltage V
O
is greater than 75% of the
input voltage V
IN
of the HV9961 LED driver.
Reducing the output LED voltage V
O
below V
O(MIN)
= V
IN
•
D
MIN
, where D
MIN
= 1.0µs/(T
OFF
+1.0µs), may also result in
the loss of regulation of the LED current. This condition,
however, causes an increase in the LED current and can
potentially trip the short-circuit protection comparator.
The typical output characteristic of the HV9961 LED driver is
shown in Fig.1. The corresponding HV9910B characteristic
is given for the comparison.
0.60
0.55
OFF Timer
LED Current (A)
The timing resistor connected to RT determines the off-time
of the gate driver, and it must be wired to GND. (Wiring this
resistor to GATE as with HV9910B is no longer supported.)
The equation governing the off-time of the GATE output is
given by:
T
OFF
(µs) =
R
T
(kΩ)
25
+ 0.3
(1)
Output Characteristics
V
IN
= 170VDC
0.50
0.45
0.40
0.35
0.30
0.25
0
10
20
30
40
within the range of 30kΩ ≤ R
T
≤ 1.0MΩ.
HV9961
Average Current Control Feedback and Output
Short Circuit Protection
The current through the switching MOSFET source is aver-
aged and used to give constant-current feedback. This cur-
rent is detected using a sense resistor at the CS pin. The
HV9910B
50
60
Output Voltage (V)
Fig.1. Typical output characteristic of an HV9961 LED
driver.
Supertex inc.
●
1235 Bordeaux Drive, Sunnyvale, CA 94089
●
Tel: 408-222-8888
●
www.supertex.com
5
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