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LTC1980EGN#PBF

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P16
LTC1980
7
1980f
REG (Pin 15): Bidirectional Regulator Mode Control Pin.
A
pull-up resistor is required between this pin and V
BIAS2
.
This pin is open when charging normally, has a weak pull-
down (approximately 5µA) when conditioning the battery
and a strong pull-down when in regulator mode. Pulling
this pin low forces the IC into regulator mode.
MODE (Pin 16): Selects different operating modes in both
charger and DC/DC converter configurations. Also en-
ables and disables Burst Mode operation. See Mode Pin
Operation table in Application section.
TIMER (Pin 17): A timing capacitor on this pin determines
the normal charge time for charge termination.
C(µF) = 0.25 • Time (Hours)
V
BAT
(Pin 18): This pin connects to the positive terminal of
the battery and the battery side of the power converter.
V
BIAS2
(Pin 19): Internally Generated Voltage. Bypass this
pin with a 1µF or larger ceramic capacitor (or other low
ESR capacitor). Do not connect any load to this pin.
GND (Pin 20): Signal Ground. This pin should Kelvin-
connect to the current sense resistor (R
SENSE
).
I
SENSE
(Pin 21): Current Sense Input Pin. Connects inter-
nally to a current amplifier and zero current comparator.
This pin should Kelvin-connect to the current sense resis-
tor (R
SENSE
) .
CAOUT (Pin 22): Current Amplifier Output. A program
resistor connects between this pin and PROGT (Pin 2) to
set the charge current (in constant-current mode).
OVP (Pin 23): Overvoltage Protection. This pin connects
to the tap on an optional external voltage divider con-
nected across the battery. This allows nonstandard float
voltages to be used for the battery charger. Overvoltage,
restart and undervoltage thresholds will also be affected
by the external voltage division ratio. To use this pin,
BATT1 (Pin 9) must float.
SS (Pin 24): Soft-Start. A capacitor between this pin and
ground sets the battery charge ramp rate. Battery charge
current is very low the moment after the converter switches
from DC/DC converter (regulator) mode to battery charger
mode then ramps up to final battery charge current from
there. This insures that the wall adapter is not loaded down
with a large inrush current that could prevent correct
battery charger operation.
The same capacitor, which sets the soft-start ramp rate,
also sets the compensation for the battery float voltage
control loop.
UU
U
PI FU CTIO S
LTC1980
8
1980f
BLOCK DIAGRA
W
–
+
–
+
–
+
–
+
–
+
–
+
–
+
V
MAX
V
DD
REG
MODE
REFERENCE
18
13
6
21
22
7
19
16
2
3
4
15
8
20
24
11
14
12
17
1
V
REF
V
REF
–
+
–
+
V
REF
V
REF
V
REF
V
REF
AC
V
REF
V
REF
V
REF
START
SHORT CYCLE
TIMEOUT
TIMER
23
10
9
H = BURST MODE OPERATION OFF
OPEN = BURST MODE OPERATION ON
L = DISABLE
L
H
–
++
–
+
–
+
–
V
REF
V
REG
V
BAT
V
REF
V
REF
CAOUT
DUMP
XFMR
RAMP
OSC
S
Q
R
AC
V
M
REG
BURST
WAKE
SLEEP
DIS
UVL
REF_UVL
V
BAT
V
REG
V
C
MODE
V
BIAS2
5µA
SS
REG
WA
GND
GM
RECHARGE
CONDITION BATTERY
EA
TIMER
PROG
1980 BD
PWM
COMP
LDOFB
LDODRV
SR_EN
I = O
COMP
I
SENSE
PGND
RGTDR
BGTDR
PROGT
REGFB
V
BIAS1
GM
BATT2
BATT1
OVP
5
LTC1980
9
1980f
The LTC1980 is an IC designed to provide a regulated
voltage to a system load from an unregulated or regulated
wall adapter, or from a battery and also charge a battery,
thereby providing an uninterruptable power source for the
system. When the wall adapter is present it provides
power to the system load and, if needed, a portion of the
power can be used to simultaneously charge the battery.
If the wall adapter is removed, the LTC1980 uses the
battery as a power source to continue providing a regu-
lated output voltage to power the system.
Combining these two functions into a single IC reduces
circuit area compared to presently available solutions
OPERATIO
U
(Figure 1). The unique bidirectional power converter to-
pology (Figure 2) accounts for much of the area savings.
A transformer based design allows the wall adapter volt-
age to be less than or greater than the battery voltage.
The LTC1980 includes a 300kHz DC/DC PWM converter
that operates in two modes. The first mode is when the wall
adapter is present and the LTC1980 is used to charge the
battery using a constant-current/constant-voltage charge
scheme. The second mode is when the wall adapter is
removed and the battery powers the LTC1980 and the
DC/DC converter generates a regulated output voltage.
POWER ROUTING
Existing Methods
Using the LTC1980
LOW DROPOUT
REGULATOR
TO SYSTEM LOAD
DC/DC CONVERTERS
TO SYSTEM LOAD
DC/DC CONVERTERS
FROM WALL ADAPTER
1980 F01
FROM
WALL ADAPTER
PWM
REGULATOR
BATTERY
CHARGER
CHARGE
TERMINATION
LTC1980-BASED
POWER DESIGN
Figure 1. Portable Power Systems
LTC1980
I
SENSE
•
•
Li-Ion
BATTERY
T1
WALL
ADAPTER
1980 F02a
SYSTEM LOAD
DC/DC
CONVERTERS
BAT-FET
REG-FET
R
S
Figure 2. LTC1980 Bidirectional Power Conversion
(a) Battery Charger Mode
LTC1980
I
SENSE
•
•
Li-Ion
BATTERY
T1
1980 F02a
SYSTEM LOAD
DC/DC
CONVERTERS
BAT-FET
REG-FET
R
S
(b) DC/DC Converter Mode (Wall Adapter Removed)
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P16

LTC1980EGN#PBF

Mfr. #:
Buy LTC1980EGN#PBF
Manufacturer:
Analog Devices / Linear Technology
Description:
Battery Management Combination Bat Chr & DC/DC Conv
Lifecycle:
New from this manufacturer.
Delivery:
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