HV9861ANG-G Supertex, HV9861ANG-G Datasheet - Page 6

• Manufacturer Part Number: HV9861ANG-G
• Description: LED Lighting Drivers LED DRIVER AVG MODE CONSTANT CURRENT
• Manufacturer: Supertex

Specifications of HV9861ANG-G

• Product Category: LED Lighting Drivers
• Rohs: yes
• Input Voltage: 12 V to 450 V
• Maximum Supply Current: 3.5 mA
• Maximum Operating Temperature: + 150 C
• Mounting Style: SMD/SMT
• Package / Case: SOIC-16
• Minimum Operating Temperature: - 40 C
• Power Dissipation: 1000 mW
• Factory Pack Quantity: 45

The short circuit protection comparator trips when the volt-
age at CS exceeds 0.45V. When this occurs, the GATE off-
time T
of the inductor current and potentially its saturation due to
insufficient output voltage. The typical short-circuit current is
shown in the waveform of Fig. 2.
A leading-edge blanking delay is provided at CS to prevent
false triggering of the current feedback and the short circuit
protection.
Linear Dimming
When the voltage at LD falls below 1.5V, the internal 270mV
reference to the constant-current feedback becomes over-
ridden by V
remains continuous, the LED current is given by the equa-
tion (3) above. However, when V
GATE output becomes disabled. The GATE signal recovers,
when V
tions to be able to shut the LED lamp off with the same signal
input that controls the brightness. The typical linear dimming
response is shown in Fig.3.
The linear dimming input could also be used for “mixed-
mode” dimming to expand the dimming ratio. In such case a
Doc.# DSFP-HV9861A
B022613
Fig.3. Typical linear dimming response of an HV9861A
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0
0.45V/R
HICCUP
0
LD
exceeds 200mV. This is required in some applica-
Fig.2. Short-circuit inductor current.
CS
LD
0.2
= 650µs is generated to prevent stair-casing
• 0.18. As long as the current in the inductor
LD Response Characteristics
0.4
650µs
LED driver
0.6
LD (V)
0.8
LD
falls below 150mV, the
1.0
1.2
1.4
1.6
6
pulse-width modulated signal of a measured amplitude be-
low 1.5V should be applied at LD.
Input Voltage Regulator
The 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 constant 7.5V level
at VDD. This voltage can be used to power the IC and ex-
ternal circuitry connected to VDD within the rated maximum
current or within the thermal ratings of the package, which-
ever 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, continu-
ous voltage at VIN is limited by the power dissipation in the
package. For example, when these ICs draw I
from the VIN input, and the 8-lead SOIC package is used,
the maximum continuous voltage at VIN is limited to:
Where the ambient temperature T
working junction temperature T
to-ambient thermal resistance R
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 pow-
er loss from the IC. In the above example, using a 100V
Zener diode will allow the circuit to work up to 490V. The
input current drawn from the VIN pin is represented by the
following equation:
In the above equation, f
is the GATE charge of the external FET obtained from the
manufacturer’s datasheet.
GATE Output
The GATE output of the HV9861A is used to drive an exter-
nal MOSFET. It is recommended that the gate charge Q
of the external MOSFET be less than 25nC for switching
frequencies ≤100kHz and less than 15nC for switching fre-
quencies >100kHz.
V
I
IN
IN(MAX)
≈ 1.0mA + Q
=
T
J(MAX)
R
θ,J-A
G
S
• f
is the switching frequency, and Q
- T
• I
S
IN
A
= 390V
J(MAX)
θ,JA
A
= 128
= 25
= 125
Supertex inc.
O
O
C/W.
C, the maximum
O
www.supertex.com
HV9861A
C, the junction-
IN
= 2.0mA
(5)
(6)
G
G