Linear Technology LTC3350, Руководство пользователя

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LTC3350
1
3350fc
For more information www.linear.com/LTC3350
Typical applicaTion
FeaTures DescripTion
High Current Supercapacitor
Backup Controller and
System Monitor
The LTC
®
3350 is a backup power controller that can charge
and monitor a series stack of one to four supercapacitors.
The LTC3350’s synchronous step-down controller drives
N-channel MOSFETs for constant current/constant voltage
charging with programmable input current limit. In addition,
the step-down converter can run in reverse as a step-up
converter to deliver power from the supercapacitor stack
to the backup supply rail. Internal balancers eliminate the
need for external balance resistors and each capacitor has
a shunt regulator for overvoltage protection.
The LTC3350 monitors system voltages, currents, stack
capacitance and stack ESR which can all be read over
the I
2
C/SMBus. The dual ideal diode controller uses
N-channel MOSFETs for low loss power paths from the
input and supercapacitors to the backup system supply.
The LTC3350 is available in a low profile 38-lead 5mm
×
7mm
×
0.75mm QFN surface mount package.
High Current Supercapacitor Charger and Backup Supply
applicaTions
n
High Efficiency Synchronous Step-Down CC/CV
Charging of One to Four Series Supercapacitors
n
Step-Up Mode in Backup Provides Greater
Utilization of Stored Energy in Supercapacitors
n
14-Bit ADC for Monitoring System Voltages/Currents,
Capacitance and ESR
n
Active Overvoltage Protection Shunts
n
Internal Active Balancers—No Balance Resistors
n
V
IN
: 4.5V to 35V, V
CAP(n)
: Up to 5V per Capacitor,
Charge/Backup Current: 10+A
n
Programmable Input Current Limit Prioritizes System
Load Over Capacitor Charge Current
n
Dual Ideal Diode PowerPath™ Controller
n
All N-FET Charger Controller and PowerPath Controller
n
Compact 38-Lead 5mm
×
7mm QFN Package
n
High Current 12V Ride-Through UPS
n
Servers/Mass Storage/High Availability Systems
L
, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
PowerPath are trademarks of Linear Technology Corporation. All other trademarks are the
property of their respective owners. Patents pending.
Backup Operation
V
IN
PFI OUTFB
OUTFET
TGATE
SW
BGATE
ICAP
VCAP
CAP4
CAP3
CAP2
CAP1
CAPRTN
CAPFB
INFET VOUTSP VOUTSN
I
CHG
(STEP-DOWN) I
BACKUP
V
CAP
< V
OUT
(STEP-UP)
V
CAP
> V
OUT
(DIRECT
CONNECT)
V
OUT
LTC3350
10F
V
CAP
10F
10F
10F
3350 TA01a
I
2
C
V
IN
2V/DIV
V
CAP
2V/DIV
V
OUT
2V/DIV
400ms/DIV
BACK PAGE APPLICATION CIRCUIT
0V
3350 TA01a
P
BACKUP
= 25W
V
OUT
V
CAP
V
IN