CAT3224
http://onsemi.com
8
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.
