HV9967DB1 Supertex, HV9967DB1 Datasheet - Page 4

• Manufacturer Part Number: HV9967DB1
• Description: LED Lighting Development Kits 4W LED DRV DEMOBOARD w/ACC CONSTANT CURR
• Manufacturer: Supertex

Specifications of HV9967DB1

• Supply Voltage: 60 V
• Supply Current: 1 mA
• For Use With/related Products: HV9967
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Functional Block Diagram
Application Information
General description
The HV9967 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
peak-current control ICs, such as HV9910B. The inductor
current ripple amplitude does not affect this control scheme
significantly, and therefore, the LED current is independent
of the variation in inductance, switching frequency or output
voltage. Constant off-time control of the buck converter is
used for stability and to reduce input voltage regulation of
the LED current.
OFF Timer
The timing resistor connected to RT determines the off-time
of the gate driver, and it must be wired to VDD. The equation
governing the off-time of the GATE output is given by:
within the range of 10kΩ ≤ R
T
OFF
Supertex inc.
= R
T
• 100pF
0.41V
Blanking
L/E
V
T
CS
≤ 400kΩ.
IN
Average Current
●
Control Logic
1235 Bordeaux Drive, Sunnyvale, CA 94089
OUT
SET
0.8ms
Timer
OTP
R
S
T
(1)
OFF
Q
Q
4
UVLO
POR
Average Current Control Feedback and Output Short
Circuit Protection
The constant-current control feedback derives the aver-
age current signal from the source current of the switching
MOSFET. This current is detected using a sense resistor at
the RSENSE pin. The feedback operates in a fast open-loop
mode. No compensation is required. Output current is pro-
grammed simply as:
The above equation is only valid for continuous conduction
of the output inductor. It is a good practice to design the in-
ductor such that the switching ripple current in it is 30~40%
of its average full load DC current peak-to-peak. Hence, the
recommended inductance can be calculated as:
The duty-cycle range of the current control feedback is lim-
ited to D ≤ 0.8. A reduction in the LED current may occur
when the LED string voltage V
input voltage V
Timer
RT
4.7V
100kΩ
I
L
i
LED
O
VDD
●
=
=
Tel: [phone]
V
0.25V
IN
R
O(MAX)
0.4 • I
CS
of the HV9967 LED driver.
REG
• T
O
HV9967
PGND
OFF
SW
V
CS
●
www.supertex.com
O
is greater than 80% of the
AGND
RSENSE
PWMD
PGND
HV9967
(2)
(3)