18-Bit ADC with I2C Interface and Onboard Reference DS

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 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

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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

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 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

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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

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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.

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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  

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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 

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

+

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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

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 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

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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.

Maker
Microchip Technology Inc.