LTC1960CG#TR Linear Technology, LTC1960CG#TR Datasheet - Page 18

• 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
LTC1960
The Current DAC Block
The current DAC is a delta-sigma modulator which controls
the effective value of an internal resistor, R
used to program the maximum charger current. Figure 6 is
a simplified diagram of the DAC operation. The delta-sigma
modulator and switch convert the IDAC value, received
via SPI communication, to a variable resistance equal to
1.25R
driven to the 0.8V reference voltage, V
rent from R
the voltage between pins CSP and CSN. This current is
(V
Therefore, programmed current is:
18
CSP
I
AVG
SET
– V
=
/(IDAC
CSN
(1.25R
SET
)/3k.
is matched against a current derived from
V
(VALUE)
REF
SNS
• 3k
R
/1023). In regulation, I
SET
)
•
I
MAX

 
IDAC
Figure 7. Charging Current Waveform in Low Current Mode
/8
0
I
SET
C
1023
SET
(VALUE)
REF
(FROM CA1 AMPLIFIER)
, and the cur-
SET
(V
SET
Figure 6. Current DAC Operation
R
18.77k
~40ms
CSP
SET

 
= 18.77k,
3k
– V
is servo
CSN
V
REF
)
AVERAGE CHARGER CURRENT
MODULATOR
+
–
∆Σ
When the low current mode bit (D10) is set to 1, the current
DAC enters a different mode of operation. The current DAC
output is pulse-width modulated with a high frequency clock
having a duty cycle value of 1/8. Therefore, the maximum
output current provided by the charger is I
delta-sigma output gates this low duty cycle signal on
and off. The delta-sigma shift registers are then clocked
at a slower rate, about 40ms/bit, so that the charger has
time to settle to the I
charging current is equal to 1/8 of the current programmed
in normal mode. Dual battery charging is disabled in low
current mode. If both batteries are selected for charging,
then only BAT1 will charge.
10
TO
I
DAC
VALUE
(10 BITS)
TH
1960 F06
MAX
1960 F07
/8 value. The resulting average
MAX
/8. The
1960fb