CPC9909NE Clare, CPC9909NE Datasheet - Page 5

• Manufacturer Part Number: CPC9909NE
• Description: IC LED DRVR HIGH BRIGH SOIC-8EP
• Manufacturer: Clare
• Type: HBLED Driverr

Specifications of CPC9909NE

• Mfg Application Notes: CPC9909 Design Considerations
• Constant Current: Yes
• Topology: AC DC Offline Switcher, PWM
• Number Of Outputs: 1
• Internal Driver: Yes
• Type - Secondary: High Brightness LED (HBLED)
• Frequency: 30kHz ~ 120 kHz
• Voltage - Supply: 12 V ~ 550 V
• Voltage - Output: 7.8V
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width) Exposed Pad, 8-eSOIC. 8-HSOIC
• Operating Temperature: -40°C ~ 85°C
• Internal Switch(s): No
• Efficiency: 90%
• Operating Supply Voltage: 8 V to 550 V
• Maximum Power Dissipation: 2.5 W
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Output / Channel: -
• Lead Free Status / Rohs Status: Details
• Other names: CLA328

2. Functional Description
Figure 1 Typical Application Circuit
2.1 Overview
The CPC9909 drives the LEDs via a minimum
off-time, peak-current-limited, pulse-frequency
modulation scheme. This control scheme is inherently
stable, and the driver can be operated above a 50%
duty cycle without any open-loop instability or
sub-harmonic oscillations. Since the switching
frequency depends on the LED load current, it results
in a high efficiency operation.
2.2 LED Driver Theory of Operation
The typical application circuit is as shown in
When PWMD is high, the control circuit is enabled and
the gate driver turns on the external power MOSFET
(Q1), causing the inductor (L1) current to ramp up until
the voltage across the current sense resistor (R
exceeds V
exceeds this threshold, the gate driver turns Q1 off.
Q1 remains off for the duration of the fixed minimum
off-time. While the switch is off, the inductor continues
to deliver the current to the load though the diode
(D1). When the off-time expires, Q1 turns on again
until the peak current limit is reached, and the process
repeats.
R01
8 - 550V
V
DD
CS(high)
C
VDD
. When the voltage at the CS pin
R
T
PWMD
V
V
R
LD
DD
IN
T
+
+
-
-
Reference
Voltage
Regulator
Voltage
Figure 1
Buck Configuration
SENSE
www.clare.com
)
R
Q
T
S
R
Minimum Off-Time
Q
One Shot
CPC9909
The peak current limit threshold is set by the external
sense resistor, R
threshold, V
also be set externally via the LD pin. The lower of
these two thresholds and R
in the inductor.
A soft start function can be implemented by ramping
up the DC voltage at the LD pin from 0V to V
the desired rate. To utilize the soft start function,
connect a resistor divider from V
capacitor from the LD pin to ground, as shown in
Figure
Figure 2 Soft-Start Circuit
TRIG
2.
V
CS
GND
GATE
IN
CS(high)
CPC9909
GND
SENSE
. This internal voltage threshold can
PWMD
V
, and the internal voltage
LD
R
DD
T
CS
GATE
SENSE
2.2kΩ
R
DD
Q1
SENSE
set the peak current
D1
to ground and a
51kΩ
0.1μF
CPC9909
L1
CS(high)
at
5