LTC3625-1_15 Datasheet, PDF (1/16 Pages) Linear Technology – 1A High Efficiency 2-Cell Supercapacitor Charger with Automatic Cell Balancing

LTC3625/LTC3625-1
1A High Efficiency 2-Cell
Supercapacitor Charger
with Automatic Cell
Balancing
Features
n _{High Efficiency Step-Up/Step-Down Charging of Two}
Series Supercapacitors
n _{Automatic Cell Balancing Prevents Capacitor}
Overvoltage During Charging
n _{Programmable Charging Current Up to 500mA}
(Single Inductor), 1A (Dual Inductor)
n _{VIN = 2.7V to 5.5V}
n _{Selectable 2.4V/2.65V Regulation per Cell (LTC3625)}
n _{Selectable 2V/2.25V Regulation per Cell (LTC3625-1)}
n _{Low No-Load Quiescent Current: 23µA}
n _{IVOUT, IVIN < 1µA in Shutdown}
n _{Low Profile 12-lead 3mm × 4mm DFN Package}
Applications
n _{Servers, RAID Systems, Mass Storage, High Current}
Backup Supplies
n _{Solid State Hard Drives}
n _{Wireless Power Meters}
n _{High Peak Power Boosted Supplies}
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the property
of their respective owners.
Description
The LTC^®3625/LTC3625-1 are programmable supercapaci-
tor chargers designed to charge two supercapacitors in
series to a fixed output voltage (4.8V/5.3V or 4V/4.5V
selectable) from a 2.7V to 5.5V input supply. Automatic
cell balancing prevents overvoltage damage to either
supercapacitor while maximizing charge rate. No balancing
resistors are required.
High efficiency, high charging current, low quiescent cur-
rent and low minimum external parts count (one inductor,
one bypass capacitor at V_IN and one programming resistor)
make the LTC3625/LTC3625-1 ideally suited for small form
factor backup or high peak power systems.
Charging current/maximum input current level is pro-
grammed with an external resistor. When the input supply is
removed and/or the EN pin is low, the LTC3625/LTC3625-1
automatically enter a low current state, drawing less than
1µA from the supercapacitors.
The LTC3625/LTC3625-1 are available in a compact
12‑lead 3mm × 4mm × 0.75mm DFN package.
Typical Application
1A SCAP Charger
V_IN
2.7V TO 5.5V
V_IN
10µF
LTC3625
61.9k
PROG
V_OUT
SW2
SW1
V_MID
3.3µH
3.3µH
PFI
EN
CTL
V_SEL
PGOOD
PFO
3625 TA01a
V_OUT
4.8V
C_TOP ≥ 0.1F
C_BOT ≥ 0.1F
Charging Two 2:1 Mismatched Supercapacitors
6
C_TOP = 50F
5
C_BOT = 100F
R_PROG = 61.9k
CTL = 0
4 ^{VSEL = 0}
V_OUT
3
2
V_MID
1
0
0 20 40 60 80 100 120 140 160 180 200
TIME (SECONDS)
3625 TA01b
3625f