LTC3226_12 Datasheet, PDF (1/16 Pages) Linear Technology – 2-Cell Supercapacitor Charger

FEATURES
n _{1x/2x Multimode Charge Pump Supercapacitor}
Charger
n _{Automatic Cell Balancing}
n _{Ideal Diode Main PowerPath™ Controller}
(V_IN to V_OUT)
n _{Internal 2A LDO Backup Supply (CPO to VOUT)}
n _{Automatic Main/Backup Switchover}
n _{Input Voltage Range: 2.5V to 5.5V}
n _{Programmable SCAP Charge Voltage}
n _{Programmable Input Current Limit (315mA Max)}
n _{No Load IVIN = 55μA (Typical)}
n _{Low Profile, 16-Lead 3mm × 3mm QFN Package}
APPLICATIONS
n _{Smart Power Meters}
n _{Battery-Powered Industrial/Medical Equipment}
n _{3.3V Solid-State Drives}
n _{Industrial Alarms}
n _{Data Backup Supplies}
n _{Battery Hold-Up Supplies}
L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks
and PowerPath is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners.
LTC3226
2-Cell Supercapacitor
Charger with Backup
PowerPath Controller
DESCRIPTION
The LTC^®3226 is a 2-cell series supercapacitor charger with
a backup PowerPath controller. It includes a charge pump
supercapacitor charger with programmable output voltage,
a low dropout regulator, and a power-fail comparator for
switching between normal and backup modes.
The constant input current supercapacitor charger is
designed to charge two supercapacitors in series to a
resistor-programmable output voltage of 2.5V to 5.3V.
The charger input current limit is programmable by an
external resistor at up to 315mA.
The internal backup LDO is powered from the superca-
pacitors and provides up to 2A peak output current with
an adjustable output voltage. When the input supply falls
below the power-fail threshold, the LTC3226 automatically
enters a backup state in which the supercapacitors power
the output through the LDO. The input supply power-fail
voltage level is programmed by an external resistor divider.
Low input noise, low quiescent current and a compact
footprint make the LTC3226 ideally suited for small, battery-
powered applications. Internal current limit and thermal
shutdown circuitry allow the device to survive a continu-
ous short-circuit from the PROG or CPO pins to ground.
TYPICAL APPLICATION
3.3V Backup Supply
MPEXT
TO LOAD
(2A)
V_IN
3.3V
V_IN
2.2μF
1.96M
1.21M
2.2μF
33.2k
1.2V +
PFI _–
C⁺
V_IN
C^–
PROG
EN_CHG
PFO
RST
CAPGOOD
LTC3226
LDO
CHARGE
PUMP
GND
GATE
V_OUT
LDO_FB
RST_FB
CPO
VMID
CPO_FB
255k
C_OUT
47μF
80.6k
5V
C_SC
1.2F
3.83M
1.21M
3226 TA01a
Automatic Normal-to-Backup
Mode Switchover
6
CPO
5
C_SC = 1.2F
C_OUT = 47μF
I_LOAD = 2A
4
V_OUT
3
V_IN
2
BACKUP
1
MODE ^{BACKUP MODE}
(LDO IN
(LDO IN
REGULATION) ^DROPOUT)
0
PFO (2V/DIV)
–1
0
0.4 0.8 1.2 1.6 2.0
TIME (SECONDS)
3226 TA01b
3226fa
1