LTM8061IV-4.2#PBF Linear Technology, LTM8061IV-4.2#PBF Datasheet - Page 14

• Manufacturer Part Number: LTM8061IV-4.2#PBF
• Description: IC, BATT CHRG, Li-Ion, Li-Polymer, 2A, LGA77
• Manufacturer: Linear Technology

Specifications of LTM8061IV-4.2#PBF

• Battery Type: Li-Ion, Li-Polymer
• Input Voltage: 32V
• Battery Charge Voltage: 4.2V
• Charge Current Max: 2A
• Battery Ic Case Style: LGA
• No. Of Pins: 77
• No. Of Series Cells: 1

LTM8061
APPLICATIONS INFORMATION
RNG/SS: Soft-Start
Soft-start functionality is also supported by the RNG/SS
pin. 50μA is sourced from the RNG/SS pin, so connect-
ing a capacitor from the RNG/SS pin to ground (C
in Figure 7) creates a linear voltage ramp. The maximum
charge current follows this voltage. Thus, the charge current
increases from zero to the fully programmed value as the
capacitor charges from 0V to 1V. The value of C
calculated based on the desired time to full current (t
following the equation:
The RNG/SS pin is pulled to ground internally when charg-
ing terminates so each new charge cycle begins with a
soft-start cycle. RNG/SS is also pulled to ground during
bad-battery and NTC fault conditions, producing a graceful
recovery from a fault.
Status Pins
The LTM8061 reports charger status through two open-col-
lector outputs, the CHRG and FAULT pins. These pins can
accept voltages as high as V
when enabled. The CHRG pin indicates that the charger is
delivering current at greater than a C/10 rate, or one-tenth
of the programmed charge current. The FAULT pin signals
bad-battery and NTC faults. These pins are binary coded
as shown in Table 2:
Table 2. Status Pin State
CHRG
High
High
Low
Low
14
C
RNG/SS
Figure 7. Using the RNG/SS Pin for Soft-Start
= 50μA • t
FAULT
High
Low
High
Low
LTM8061
SS
STATUS
Standby, Shutdown Mode, or Charging at
Less than C/10
Bad-Battery Fault (Precondition Timeout/
EOC Failure)
Normal Charging at C/10 or Greater
NTC Fault (Pause)
RNG/SS
8061 F07
IN
, and can sink up to 10mA
C
RNG/SS
RNG/SS
RNG/SS
SS
is
)
If the battery is removed from an LTM8061 charger that is
configured for C/10 termination, a low amplitude sawtooth
waveform appears at the charger output, due to cycling
between termination and recharge events. This cycling
results in pulsing at the CHRG output. An LED connected
to this pin will exhibit a blinking pattern, indicating to the
user that a battery is not present. The frequency of this
blinking pattern is dependent on the output capacitance.
C/10 Termination
The LTM8061 supports a low current based termination
scheme, where a battery charge cycle terminates when
the charge current falls below one-tenth the programmed
charge current, or about 200mA. This termination mode is
engaged by shorting the TMR pin to ground. When C/10
termination is used, an LTM8061 charger sources battery
charge current as long as the average current level remains
above the C/10 threshold. As the full-charge float voltage is
achieved, the charge current falls until the C/10 threshold
is reached, at which time the charger terminates and the
LTM8061 enters standby mode. The CHRG status is high
impedance when the charger is sourcing less than C/10.
There is no provision for bad-battery detection if C/10
termination is used.
Timer Termination
The LTM8061 supports a timer-based termination scheme,
where a battery charge cycle terminates after a specific
amount of time elapses. Timer termination is enabled
by connecting a capacitor (C
GND. The timer cycle time span (t
C
When charging at a 1C rate, t
hours, which requires a 0.68μF capacitor.
The CHRG status pin continues to signal charging, regard-
less of which termination scheme is used. When timer
termination is used, the CHRG status pin is pulled low
during a charge cycle until the charge current falls below
the C/10 threshold. The charger continues to top off the
battery until timer EOC, when the LTM8061 terminates the
charge cycle and enters standby mode.
TIMER
C
TIMER
in the equation:
= t
EOC
• 2.27 • 10
–7
EOC
TIMER
(Hours)
is commonly set to three
) from the TMR pin to
EOC
) is determined by
8061f