LTC1960CG#TR Linear Technology, LTC1960CG#TR Datasheet - Page 17

• Manufacturer Part Number: LTC1960CG#TR
• Description: IC BATT CHRGR/SELECTR DUAL36SSOP
• Manufacturer: Linear Technology
• Type: Battery Chargerr

Specifications of LTC1960CG#TR

• Function: Charge Management
• Voltage - Supply: 6 V ~ 28 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 36-SSOP (0.200", 5.30mm Width)
• Operating Supply Voltage (min): 6V
• Operating Supply Voltage (max): 28V
• Operating Temp Range: 0C to 70C
• Package Type: SSOP
• Mounting: Surface Mount
• Pin Count: 36
• Operating Temperature Classification: Commercial
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: LTC1960CGTR

OPERATION
bit is set in the status register. This is a three-strikes-and-
you’re-out process which is intended to debounce the
PowerPath PF indicator. The power-fail counter is reset
by a PowerPath SPI write.
Short-Circuit Protection
Short-circuit protection operates in both a current mode
and a voltage mode. If the voltage between SCP and SCN
exceeds the short-circuit comparator threshold V
more than 15ms, then all of the PowerPath switches are
turned off and the FAULT bit (FA) is set. Similarly, if the
voltage at SCN falls below 3V for more than 15ms, then
all of the PowerPath switches are turned off and the FA bit
is set. The FA bit is reset by removing all power sources
and allowing the voltage at V
threshold. If the FA bit is set, charging is disabled until
V
quested via the SPI interface.
When a hard short-circuit occurs, it might pull all of the
power sources down to near 0V potentials. The capacitors
on V
operating correctly during the 15ms short-circuit event.
The charger will stop within a few microseconds leaving
a small current which must be provided by the capacitor
on V
V
the LTC1960 operating above the UVLO trip voltage long
enough to perform the short-circuit function when the
input voltages are greater than 8V. Increasing the capaci-
tor across V
recommended 6V minimum.
Fast PowerPath Turn-Off
All of the PowerPath switches can be forced off by set-
ting the DCDIV pin to a voltage between 8V and 10V. This
will have the same effect as a short-circuit event. The PF
status bit will also be set. DCDIV must be less than 5V
and V
re-enable the PowerPath switches.
Power-Up Strategy
All three PowerPath switches are turned on after V
exceeds the UVLO threshold for more than 250ms. This
PLUS
PLUS
CC
PLUS
PLUS
and 2µF on V
exceeds the UVLO threshold and charging is re-
and V
. The recommended minimum values (1µF on
must decrease below the UVLO threshold to
CC
PLUS
to 4.7µF will allow operation down to the
must be large enough to keep the circuit
CC
, including tolerances) should keep
PLUS
to fall below the UVLO
TSC
PLUS
for
delay is to prevent oscillation from a turn-on transient
near the UVLO threshold.
The Voltage DAC Block
The voltage DAC (VDAC) is a delta-sigma modulator
which controls the effective value of an internal resistor,
R
voltage. Figure 5 is a simplified diagram of the VDAC
operation. The charger monitor MUX is connected to the
appropriate battery indicated by the CHARGE_BATx bit.
The delta-sigma modulator and switch SWV convert the
VDAC value, received via SPI communication, to a vari-
able resistance equal to (11/8)R
In regulation, V
voltage, V
Therefore, programmed voltage is:
Note that the reference voltage must be subtracted from
the VDAC value in order to obtain the correct output volt-
age. This value is V
Capacitors C
present at the V
voltage loop to help stability and transient response time
to voltage variations. See the Applications Information
section.
CSN
VSET
V
+ V
BATx
C
B2
REF
= 7.2k, used to program the maximum charger
= (8/11) V
= 32,752mV • (VDAC
REF
BAT1
BAT2
V
B1
SET
C
.
B1
Figure 5. Voltage DAC Operation
SET
and C
SET
SWV
REF
REF
is servo driven to the 0.8V reference
pin as well as provide a zero in the
B2
405.3k
405.3k/7.2k • (VDAC
R
7.2k
/16mV = 50 (32
VSET
CHGMON
R
V
are used to average the voltage
VF
REF
VSET
(VALUE)
MODULATOR
–
+
∆Σ
/(VDAC
EA
/2047) + 0.8V
HEX
LTC1960
).
(VALUE)
(VALUE)
11
17
/2047).
DAC
VALUE
(11 BITS)
/2047)
1960fb
1960 F05
TO
I
TH