2014 Microchip Technology Inc.
DS20005333A-page 1
HV9861A
Features
• Fast average current control
• Programmable constant off-time switching
• PWM / linear dimming input
• Output short circuit protection with skip mode
• Ambient operating temperature -40°C to +125°C
• Pin-compatible with the HV9910B and HV9961
Applications
• DC/DC or AC/DC LED driver applications
• LED back-light driver for LCD displays
• General purpose constant current source
• LED signage and displays
• Architectural and decorative LED lighting
• LED street lighting
Description
HV9861A is a patented, average-mode, constant-cur-
rent control, LED driver IC operating in a constant off-
time mode. Unlike the HV9910B, this control IC does
not produce a peak-to-average error, which therefore
greatly improves the accuracy, line and load regulation
of the LED current without any need for loop compen-
sation 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. Internal
over-temperature protection is provided. The internally
regulated voltage (V
DD
) for the HV9861A is 7.5V.
The IC can be powered from a 15 - 450V supply. A
PWM dimming input is provided that accepts an exter-
nal control TTL-compatible signal. The output current
can be programmed by an internal 270mV reference,
or controlled externally through a 0 - 1.5V dimming
input.
HV9861A is pin-to-pin compatible with the HV9910B
and HV9961, and can be used as a drop-in replace-
ment for many applications to improve the LED current
accuracy and regulation.
LED Driver with Average-Mode Constant Current Control
HV9861A
DS20005333A-page 2
2014 Microchip Technology Inc.
Package Types
Typical Application Circuit
8-Lead SOIC
16-Lead SOIC
VIN
CS
GND
GATE
RT
LD
VDD
PWMD
VIN
NC
NC
CS
GND
NC
NC
GATE
NC
NC
RT
LD
VDD
NC
NC
PWMD
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
1
2
3
4
8
7
6
5
See
Table 2-1
for pin information
PWMD
VDD
LD
GATE
CS
RT
VIN
HV9861A
15VDC to
450VDC
Sets
LED
Current
LED
Load
GND
R
CS
R
T
2014 Microchip Technology Inc.
DS20005333A-page 3
HV9861A
1.0
ELECTRICAL
CHARACTERISTICS
ABSOLUTE MAXIMUM RATINGS
V
IN
to GND...................................................... -0.5V to +470V
V
DD
to GND.......................................................................12V
LD, PWMD, GATE to GND................. ....-0.3V to (V
DD
+ 0.3V)
CS, RT to GND .............................................. ....-0.3V to 5.0V
Operating temperature..................................-40°C to +125°C
Storage temperature .....................................-65°C to +150°C
Continuous power dissipation (T
A
= +25°C)
8-lead SOIC ...............................................650 mW
16-lead SOIC ...........................................1000 mW
Note: Stresses above those listed under “Absolute 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. Expo-
sure to maximum rating conditions for extended periods may
affect device reliability.
1.1
ELECTRICAL SPECIFICATIONS
TABLE 1-1:
ELECTRICAL CHARACTERISTICS (SHEET 1 OF 2)
1
Symbol
Parameter
Note
Min
Typ
Max
Units Conditions
Input
V
INDC
Input DC supply voltage
range
2
3
15
-
450
V
DC input voltage
I
INSD
Shut-down mode supply
current
3
-
0.5
1.1
mA
Pin PWMD to GND
Internal Regulator
V
DD
Internally regulated voltage
-
7.25
7.50
8.20
V
500pF at GATE; RT = 226kΩ
∆V
DD
, line Line regulation of V
DD
-
-
-
1
V
V
IN
= 15 - 450V,
500pF at GATE; RT = 226kΩ
∆V
DD
, load Load regulation of V
DD
-
-
-
100
mV
I
DD(ext)
= 0 - 1mA,
500pF at GATE; RT = 226kΩ
UVLO
V
DD
under-voltage lockout
threshold
3
6.45
-
-
V
V
IN
rising
∆UVLO
V
DD
under-voltage lockout
hysteresis
-
-
500
-
mV
V
IN
falling
∆V
DD(UV)
V
DD
voltage margin
3
500
-
-
mV
∆V
DD(UV)
= V
DD
- UVLO
I
IN,MAX
Maximum input current
(limited by UVLO)
4
3.5
-
-
mA
V
IN
= 15V, T
A
= 25°C
4
1.5
-
-
V
IN
= 15V, T
A
= 125°C
PWM Dimming
V
EN(lo)
PWMD input low voltage
3
-
-
0.8
V
V
IN
= 15 - 450V
V
EN(hi)
PWMD input high voltage
3
2.2
-
-
V
V
IN
= 15 - 450V
I
EN
Internal pull-down current at
PWMD
-
8.5
-
13.5
μA
V
PWMD
= 0.8V
HV9861A
DS20005333A-page 4
2014 Microchip Technology Inc.
Average Current Sense Logic
V
CS
Current sense reference
voltage
-
262
-
280
mV
A
V(LD)
LD-to-CS voltage ratio
-
0.175
-
0.182
-
A
V
•
V
LD(OFFSET)
LD-to-CS voltage offset
-
-10
-
10
mV
Offset = V
CS
- (A
V(LD)
• V
LD
);
V
LD
= 1.2V
∆V
CS(TEMP)
CS threshold temp regula-
tion
4
-
-
5
mV
V
LD(OFF)
LD input voltage, shutdown
-
-
150
-
mV
V
LD
falling
∆V
LD(OFF)
LD input voltage, enable
-
-
200
-
mV
V
LD
rising
T
BLANK
Current sense blanking
interval
3
140
-
290
ns
T
ON(min)
Minimum on-time
-
-
-
760
ns
CS = V
CS
+ 30mV
D
MAX
Maximum steady-state duty
cycle
3
80
-
-
%
Reduction in output LED cur-
rent may occur beyond this
duty cycle
Short Circuit Protection
V
CS
Hiccup threshold voltage
3
410
-
510
mV
T
DELAY
Current limit delay CS-to-
GATE
-
-
-
150
ns
CS = V
CS
+ 30mV
T
HICCUP
Short circuit hiccup time
-
400
-
850
μs
T
ON(min)
Minimum on-time (short circuit)
-
-
-
430
ns
CS = 4V
TOFF Timer
T
OFF
Off-time
-
32
40
48
μs
R
T
= 1MΩ
-
8
10
12
R
T
= 226kΩ
GATE Driver
I
SOURCE
Sourcing current
-
0.165
-
-
A
V
GATE
= 0V, V
DD
= 7.5V
I
SINK
Sinking current
-
0.165
-
-
A
V
GATE
= VDD, V
DD
= 7.5V
t
RISE
Output rise time
-
-
30
50
ns
C
GATE
= 500pF, V
DD
= 7.5V
t
FALL
Output fall time
-
-
30
50
ns
C
GATE
= 500pF, V
DD
= 7.5V
Over-Temperature Protection
T
SD
Shut-down temperature
4
128
140
-
°C
---
∆T
SD
Hysteresis
4
-
20
-
°C
---
1
Specifications are T
A
= 25°C, V
IN
= 15V, V
LD
= V
DD
, PWMD = V
DD
unless otherwise noted.
2
Also limited by package-power dissipation limit; Whichever is lower.
3
Applies over the full operating ambient temperature range of -40°C < T
A
< +125°C.
4
For design guidance only
TABLE 1-1:
ELECTRICAL CHARACTERISTICS (CONTINUED) (SHEET 2 OF 2)
1
Symbol
Parameter
Note
Min
Typ
Max
Units Conditions
TABLE 1-2:
THERMAL RESISTANCE
Package
θja
8-Lead SOIC
101°C/W
16-Lead SOIC
83°C/W
2014 Microchip Technology Inc.
DS20005333A-page 5
HV9861A
2.0
PIN DESCRIPTION
The locations of the pins are listed in
Package Types
.
TABLE 2-1:
PIN DESCRIPTION
Pin #
Function
Description
8-Lead SOIC 16-Lead SOIC
1
1
VIN
Input of a 15 - 450V linear regulator.
2
4
CS
Current sense pin used to sense the FET current by means of an
external sense resistor.
3
5
GND
Ground return for all internal circuitry. This pin must be electrically
connected to the ground of the power train.
4
8
GATE
Output GATE driver for an external N-channel power MOSFET.
5
9
PWMD
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.
6
12
VDD
Power supply pin for all internal circuits. It must be bypassed with a
low ESR capacitor to GND (at least 0.1μF).
7
13
LD
Linear-dimming input. Sets the current sense threshold as long as
the voltage at this pin is less than 1.5V. If voltage at LD falls below
150mV, the GATE output is disabled. The GATE signal recovers at
200mV at LD.
8
14
RT
A resistor connected between this pin and GND programs the
GATE off-time.
-
2, 3, 6, 7, 10,
11, 15, 16
NC
No connection.
HV9861A
DS20005333A-page 6
2014 Microchip Technology Inc.
3.0
APPLICATION INFORMATION
Peak-current control (as in the HV9910B) of a buck
converter is the most economical and simple way to
regulate its output current. However, this method suf-
fers accuracy and regulation problems that arise from
the so-called peak-to-average current error, contrib-
uted to by the current ripple in the output inductor and
the propagation delay in the current-sense comparator.
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 potential. While it is very simple to detect the
peak current in the switch, controlling the average
inductor current is usually implemented by level trans-
lating the sense signal from the positive supply rail.
Though this is practical for relatively low input voltage,
this type of average-current control may become
excessively complex and expensive in off line AC or
other high-voltage DC applications.
HV9861A employs a patented control scheme, achiev-
ing 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 rip-
ple amplitude does not affect this control scheme sig-
nificantly. Therefore, the LED current is independent of
the variation in inductance, switching frequency, or out-
put voltage. Constant off-time control of the buck con-
verter is used for stability and to improve the LED-
current regulation over a wide range of input voltages.
(Note that, unlike the HV9910B, this IC does not sup-
port the constant-frequency mode of operation.)
3.1
OFF Timer
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 the HV9910B is no
longer supported. The equation governing the off-time
of the GATE output is given by:
Within the range of 30kΩ ≤ R
T
≤ 1.0MΩ.
3.2
Average Current Control
Feedback and Output Short
Circuit Protection
The current through the switching MOSFET source is
averaged and used to give constant-current feedback.
This current is detected using a sense resistor at the
CS pin. The feedback operates in a fast open-loop
mode. No compensation is required. Output current is
programmed simply as:
When the voltage at the LD input V
LD
≥ 1.5V. Other-
wise:
The above equations are only valid for continuous con-
duction of the output inductor. It is a good practice to
design the inductor such that the switching ripple cur-
rent in it is 30~40% of its average peak-to-peak, full
load, DC current. Hence, the recommended inductance
can be calculated as:
The duty-cycle range of the current control feedback is
limited to D ≤ 0.8. A reduction in the LED current may
occur when the LED string voltage V
O
is greater than
80% of the input voltage V
IN
of the HV9861A LED
driver.
Reducing the output LED voltage V
O
below V
O(MIN)
=
V
IN
• D
MIN
, where D
MIN
= 760ns/(T
OFF
+760ns), may
also result in the loss of regulation of the LED current.
However, this condition causes an increase in the LED
current and can potentially trip the short-circuit protec-
tion comparator.
A typical output characteristic of the HV9861A LED
driver is shown in
Figure 3-1
. The corresponding
HV9910B characteristic is given for comparison.
FIGURE 3-1:
TYPICAL OUTPUT
CHARACTERISTIC OF AN
HV9861A LED DRIVER
T
OFF
s
R
T
k
25
-------------------- 0.3
+
=
I
LED
0.27V
R
CS
----------------
=
I
LED
V
LD
0.18
R
CS
-------------------------
=
L
V
O MAX
T
OFF
0.4 I
O
-------------------------------------
=
V
IN
= 170VDC
HV9861A
HV9910B
0 10 20 30 40 50 60
0.60
0.55
0.50
0.45
0.40
0.35
0.30
0.25
LED Current (A)
Output Voltage (V)
Output Characteristics
2014 Microchip Technology Inc.
DS20005333A-page 7
HV9861A
The short circuit protection comparator trips when the
voltage at CS exceeds 0.45V. When this occurs, the
GATE off-time T
HICCUP
= 650µs is generated to prevent
stair-casing of the inductor current, and potentially its
saturation, due to insufficient output voltage. The typi-
cal short-circuit current is shown in the waveform of
Figure 3-2
.
FIGURE 3-2:
SHORT-CIRCUIT
INDUCTOR CURRENT
A leading-edge blanking delay is provided at CS to pre-
vent false triggering of the current feedback and the
short circuit protection.
3.3
Linear Dimming
When the voltage at LD falls below 1.5V, the internal
270mV reference to the constant-current feedback
becomes overridden by V
LD
• 0.18. As long as the cur-
rent in the inductor remains continuous, the LED cur-
rent is given by the equation in
Section 3.2
. However,
when V
LD
falls below 150mV, the GATE output
becomes disabled. The GATE signal recovers, when
V
LD
exceeds 200mV. This is required in some applica-
tions to be able to shut the LED lamp off with the same
signal input that controls the brightness. The typical lin-
ear dimming response is shown in
Figure 3-3
.
FIGURE 3-3:
TYPICAL LINEAR DIMMING
RESPONSE OF AN
HV9861A LED DRIVER
The linear dimming input could also be used for “mixed-
mode” dimming to expand the dimming ratio. In such
case a pulse-width modulated signal of a measured
amplitude below 1.5V should be applied at LD.
3.4
Input Voltage Regulator
HV9861A can be powered directly from a 15 – 450VDC
supply through its VIN input. When this voltage is
applied at the VIN pin, the HV9861A maintains a con-
stant 7.5V level at VDD. This voltage can be used to
power the IC and external circuitry connected to VDD
within the rated maximum current or within the thermal
ratings of the package, whichever limit is lower. The
VDD pin must be bypassed by a low ESR capacitor to
provide a low impedance path for the high frequency
current of the GATE output. The HV9861A can also be
powered through the VDD pin directly with a voltage
greater than the internally regulated 7.5V, but less than
12V.
Despite the instantaneous voltage rating of 450V, con-
tinuous voltage at VIN is limited by the power dissipa-
tion in the package. For example, when these ICs draw
I
IN
= 3.0mA from the VIN input, and the 8-lead SOIC
package is used, the maximum continuous voltage at
VIN is limited to the following:
In this instance, the ambient temperature T
A
= 25°C, the
maximum working junction temperature T
J(MAX)
= 125°C,
and the junction-to-ambient thermal resistance R
θ,JA
=
101°C/W.
In such cases, when it is needed to operate the
HV9861A from a higher voltage, a resistor or a Zener
diode can be added in series with the VIN input to divert
some of the power loss from the IC. In the above exam-
ple, using a 100V Zener diode will allow the circuit to
work up to 430V. The input current drawn from the VIN
pin is represented by the following equation:
In the above equation, f
S
is the switching frequency,
and Q
G
is the GATE charge of the external FET
obtained from the manufacturer’s data sheet.
3.5
GATE Output
The GATE output of HV9861A is used to drive an exter-
nal MOSFET. The gate charge, Q
G
, of the external
MOSFET should be less than 25nC for switching fre-
quencies ≤100kHz and less than 15nC for switching
frequencies >100kHz.
650μs
0.45V/R
CS
0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0
LED Current (A)
LD (V)
LD Response Characteristics
V
IN MAX
T
J MAX
T
A
–
R
J A
–
I
IN
-------------------------------
330V
=
=
I
IN
1.0mA Q
G
f
s
+
HV9861A
DS20005333A-page 8
2014 Microchip Technology Inc.
3.6
PWM Dimming
Due to the fast open-loop response of the average-
mode, current-control loop of the HV9861A, the PWM
dimming performance nearly matches that of the
HV9910B. The inductor current waveform comparison
is shown in
Figure 3-4
.
FIGURE 3-4:
TYPICAL PWM DIMMING
RESPONSE OF AN
HV9861A LED DRIVER
The rising and falling edges are limited by the current
slew rate in the inductor. The first switching cycle is ter-
minated upon reaching the 270mV (V
LD
• 0.18) level at
CS. The circuit is further reaching its steady-state
within 3–4 switching cycles regardless of the switching
frequency.
FIGURE 3-5:
FUNCTIONAL BLOCK DIAGRAM
CH2 (red): PWMD
CH4 (green): Inductor Current
CH3 (blue): Same as HV9910B, for comparison
R Q
S Q
T
OFF
Timer
Latch
Enable
Blanking
0.45V
min (V
LD
•
0.18, 0.27V)
650μs
Current
Mirror
i
Regulator
VIN
LD
CS
GND
VDD
GATE
PWMD
RT
UVLO
POR
0.15/0.20V
Average Current
Control Logic
OUT
Auto-REF
HV9861A
CLK
IN
+
-
+
-
+
-
11μA
2014 Microchip Technology Inc.
DS20005333A-page 9
HV9861A
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.
8-lead SOIC
Example
NNN
XX
XXXXXXXX
YYWW
e3
343
LG
HV9861A
1447
e3
16-lead SOIC
XXXXXXXXX
XXXXXXXXXXX
YYWWNNN
e3
Example
HV9861ANG
1447343
e3
HV9861A
DS20005333A-page 10
2014 Microchip Technology Inc.
Note: For the most current package drawings, see the Microchip Packaging Specification at www.microchip.com/packaging.