HV9912 Supertex, Inc., HV9912 Datasheet - Page 5

• Manufacturer Part Number: HV9912
• Description: Switch-mode Led Driver Ic With High Current Accuracy And Hiccup Mode Protection
• Manufacturer: Supertex, Inc.

Functional Block Diagram
Functional Description
Power Topology
The HV9912 is a switch-mode converter LED driver de-
signed to control a continuous conduction mode buck or
boost in a constant frequency (or constant off-time) mode.
The IC includes an internal linear regulator, which operates
from input voltages up to 90V eliminating the need for an
external power supply for the IC. The IC includes features
typically required in LED drivers like open LED protection,
output short circuit protection, linear and PWM dimming,
programmable input current limiting and accurate control of
the LED current. A high current gate drive output enables the
controller to be used in high power converters.
The HV9912 is an enhanced version of the HV9911 with
COMP
FDBK
CLIM
IREF
VDD
VIN
CS
SC
1:2
PWMD
Hiccup/Dimming
POR
_
+
G
+
_
Blanking
M
T
ramp
BLANK
Block
OVD
5.60/6.10V
SCD
SS
Linear Regulator
_
+
2
+ _
13R
R
S
R
5
POR
T
PWMD
BLANK,SC
hysteretic over-voltage protection and hiccup mode short
circuit protection. The IC includes a blanking network con-
trolled by the PWMD input to prevent the short circuit protec-
tion from triggering prematurely during PWM dimming due
to the parasitic capacitance of the LED string. It also allows
the IREF pin to be pulled all the way down to GND without
triggering the short circuit protection. It is a pin compatible
replacement to the HV9911.
Linear Regulator
The HV9912 can be powered directly from its VIN pin that
withstands a voltage up to 90V. When a voltage is applied at
the VIN pin, the HV9912 tries to maintain a constant 7.75V
(typ) at the VDD pin. The regulator also has a built in under-
Q
PWMD
SS
OVPD
SS
V bg
GND
One Shot
SCD
5V rising
4.5V falling
Preliminary
SYNC
HV9912
REF
GATE
FAULT
RT
OVP