HV9985 Supertex, HV9985 Datasheet - Page 13

• Manufacturer Part Number: HV9985
• Description: LED Driver ICs
• Manufacturer: Supertex

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Pin Description (K6)
Pin Description (QP)
Pin
Pin
22
23
40
35
31
39
34
32
40
31
27
41
34
26
42
35
26
43
24
44
36
23
10
22
11
21
#
#
9
1
2
COMP1
COMP2
COMP3
GATE1
GATE2
GATE3
FDBK1
FDBK2
FDBK3
GND1
GND2
GND3
Name
Name
VDD1
VDD2
VDD3
OVP1
OVP2
OVP3
REF1
REF2
REF3
CLK
CS1
CS2
CS3
FT1
FT2
FT3
RT
Description
A resistor at this pin programs the on-board oscillator. If an external clock is being used, this pin should
be connected to VDD.
This pin is the clock input for the HV9985. The input to the CLK pin should be a TTL compatible square
wave signal. The three channels will switch at 1/12th the switching frequency of the signal applied at the
CLK pin. This pin is used if more than one HV9985’s are being used in a system. If the on-chip oscillator
is being used, this pin should be connected to GND.
These pins are the gate drivers which drive the external logic-level, N-channel boost converter MOS-
FETs.
Ground return for each of the channels. It is recommended that all the GNDs of the IC be connected
together in a STAR connection at the input GND terminal to ensure best performance.
Description
These pins are the power supply pins of the three channels. They can either be connected to the VDD
pin or supplied with an external power supply. They must be bypassed with a low ESR capacitor to their
respective GNDs (at least 0.1μF). All VDD pins (VDD, VDD1-3) must be connected together externally.
An external 5.0V supply can be connected to these pins to power the IC if the internal regulator is not
used.
These pins are used to drive external logic-level disconnect switches. The disconnect switches are used
to protect the LEDs in case of fault conditions and also serve to provide excellent PWM dimming re-
sponse by disconnecting and reconnecting the LEDs from the output capacitor during PWM dimming.
These pins are used to sense the source current of the external power FETs. They include a built-in
100ns (min) blanking timer. Connecting an RC-network at these pins programs the slope compensation.
Refer to the Slope Compensation section for additional information.
Stable closed loop control can be accomplished by connecting a compensation network between each
COMP pin and its respective GND.
These pins are the output current feedback inputs for each channel. They receive voltage signal from
external sense resistors.
The voltage at this pin sets the output current level for channel 1. Recommended voltage range for this
pin is 0 – 1.25V.
These pins provide the over voltage protection for the three channels. When the voltage at any of these
pins exceeds 1.25V, the HV9985 is turned off. The fault timer starts when the voltage drops below
1.125V. Upon completion of the fault timer the IC attempts to restart.
(cont.)
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1235 Bordeaux Drive, Sunnyvale, CA 94089
13
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Tel: [phone]
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www.supertex.com
HV9985