CAT3224 Datasheet, PDF (8/13 Pages) ON Semiconductor – 4 Amp Supercapacitor Flash LED Driver

CAT3224
Table 6. PIN DESCRIPTION
Pin #
Name
Function
1
RF
Flash Current Setting Resistor terminal
2
BAL
Active Supercapacitor Balance Control
3, 4
CAP
Supercapacitor Positive Connection
5
CHRG
Charge Supercapacitor Enable
6
FLASH
Flash Enable
7
TORCH
Torch Enable
8
FLAG
Flash Ready Flag output, Open drain (Active low)
9
LEDB
LED B channel anode (+) connection
10
LEDA
LED A channel anode (+) connection
11
RC
Charge Current Setting Resistor terminal
12
RT
Torch Current Setting Resistor terminal
13
VIN
Positive supply connection to battery
14
CP
Bucket capacitor Positive terminal
15
CN
Bucket capacitor Negative terminal
16
GND
Device ground connection
TAB
TAB
Connect to GND on the PCB
Pin Function
VIN is the supply pin for the device and for the
supercapacitor charger circuit. A small 1 mF ceramic bypass
capacitor is required between the VIN pin and ground near
the device.
GND is the ground reference for the charge pump. This pin
must be connected to the ground plane on the PCB.
TAB is the exposed pad underneath the package. For best
thermal performance, the tab should be soldered to the PCB
and connected to the ground plane.
CAP is the positive connection to the supercapacitor.
Current sinks or sources from this pin to the capacitor
depending on the mode of operation.
CP, CN pins are connected to each side of the ceramic
bucket capacitor used in the 2x charge pump mode.
LEDA, LEDB are connected internally to the current
sources and must be connected to the LED anodes. Each
output is independently current regulated. These pins enter
a high−impedance ‘zero’ current state whenever the device
is placed in shutdown mode or FLASH and TORCH are low.
BAL is connected to the center−point between the two
supercapacitor cells. An active circuit forces the BAL pin to
remain at half of the voltage of the CAP output.
RF is connected to a resistor (R_F) to set the current in the
LED channels in flash mode. The voltage on the pin is
regulated to 0.6 V in flash mode (FLASH high).
RT is connected to a resistor (R_T) to set the current in the
LED channels in torch mode. The voltage on the pin is
regulated to 0.6 V in torch mode (TORCH high).
RC is connected to a resistor (R_C) to set the current limit on
VIN when charging the supercapacitor. The voltage on the
pin is regulated to 0.6 V in charge mode (CHRG high).
CHRG is the charge mode enable pin. When high, the 1x/2x
charge pump is enabled and allows to charge the
supercapacitor and monitors its voltage.
FLASH is the flash mode enable pin. When high, the LED
current sources are enabled in flash mode. If FLASH is kept
high for longer then 300 ms typical, the LED channels are
automatically disabled.
TORCH is the torch mode enable pin. When high, the LED
current sources are enabled in torch mode.
FLAG is an active−low open−drain output that notify to the
microcontroller that the supercapacitor is fully charged by
pulling the output low. When using the flag, this pin should
be connected to a positive rail via an external pull−up
resistor.
http://onsemi.com
8