CAT3604VHV4-GT2 CATALYST SEMICONDUCTOR, CAT3604VHV4-GT2 Datasheet - Page 11

• Manufacturer Part Number: CAT3604VHV4-GT2
• Description: IC, LED DRIVER, CHARGE PUMP, TQFN-16
• Manufacturer: CATALYST SEMICONDUCTOR

Specifications of CAT3604VHV4-GT2

• Led Driver Application: LCD Display Backlight, Digital Still Cameras
• No. Of Outputs: 4
• Output Current: 30mA
• Output Voltage: 7V
• Input Voltage: 2.5V To 5.5V
• Topology: Charge Pump
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

device runs diagnostics and goes to 1x mode where the
output is basically equal to the input voltage.
itself and reevaluate the mode.
a thermal protection shutdown mode. When the device
temperature drops to about +130°C, the device resumes
normal operation.
LED Selection
4.3 V may be used. Selecting LEDs with lower V
recommended in order to extend battery life and keep the
driver in 1x mode longer as the battery voltage decreases.
3.5 V V
supply voltage of 0.2 V.
External Components
for decoupling input, output, and for the charge pump. Both
capacitors type X5R and X7R are recommended for the
LED driver application. In all charge pump modes, the input
current ripple is kept very low by design and an input bypass
capacitor of 1 mF is sufficient.
not introduce switching noise back onto the supply.
Recommended Layout
high frequency. It is recommended to minimize trace length
to all four capacitors. A ground plane should cover the area
under the driver IC as well as the bypass capacitors. Short
connection to ground on capacitors C
implemented with the use of multiple via. A copper area
matching the TQFN exposed pad (TAB) must be connected
to the ground plane underneath. The use of multiple via
improves the package heat dissipation.
As soon as the output exceeds about 6 V, the driver resets
If the die temperature reaches +150°C, the device enters
LEDs with forward voltages (V
For example, if a 3.3 V V
The driver requires four external 1 mF ceramic capacitors
In 1x mode, the device operates in linear mode and does
In charge pump mode, the driver switches internally at a
F
LED, the driver will stay in 1x mode for a lower
Figure 27. PCB Layout
F
LED is selected instead of a
F
) ranging from 1.3 V to
IN
and C
OUT
http://onsemi.com
can be
F
is
11
PWM Dimming
as well as High Resolution PWM dimming control on the
LED Channels.
held low for 1.5 ms. During the “soft−start” power−up
sequence from the shutdown mode, the LED current
typically settles within 40 ms (for 1X mode operation). This
LED current settling time becomes 400 ms if 1.33X
operation is needed (i.e low battery voltage).
frequencies at 2 kHz or above), the device will remain
powered and only the LED channels output will be switched
on and off during the PWM (the rest of the device will
remain powered−up). This allows the output channels to
have “instant−on” response, where the LED current settles
within 1 ms of the applied PWM dimming signals. This
“instant−on” modes makes the device suitable for extremely
high frequency PWM dimming schemes.
up to 100 kHz and with duty cycles of 30% and 70%.
should meet the following timing limits:
•
•
The EN pin is used to provide total Shutdown of the device
Shutdown of the device occurs after the EN pin has been
For High Resolution PWM dimming control (typically
Figure 28 shows the output current for PWM frequencies
For best performance, the duty cycle off−time T
for slow frequency ≤ 600 Hz, T
for fast frequency ≥ 1 kHz, T
100
90
80
70
60
50
40
30
20
10
Figure 28. Output Current vs. PWM Frequency
0.1
30% DC
70% DC
PWM FREQUENCY (kHz)
1
OFF
OFF
≤ 400 ms
≥ 800 ms
10
100
OFF