LTC4011CFE#TRPBF Linear Technology, LTC4011CFE#TRPBF Datasheet - Page 12

• Manufacturer Part Number: LTC4011CFE#TRPBF
• Description: IC BATT CHARGER HIEFF 20TSSOP
• Manufacturer: Linear Technology

Specifications of LTC4011CFE#TRPBF

• Function: Charge Management
• Battery Type: Nickel Cadmium (NiCd), Nickel Metal-Hydride (NiMH)
• Voltage - Supply: 4.5 V ~ 34 V
• Operating Temperature: 0°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 20-TSSOP (0.173", 4.40mm Width) Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

operaTion
LTC4011
Shutdown State
The LTC4011 remains in micropower shutdown until DCIN
(Pin 1) is driven above V
and PWM outputs and internally generated terminations
or supply voltages are inactive. Current consumption from
V
Charge Qualification State
Once DCIN is greater than V
micropower shutdown, enables its own internal supplies,
provides V
V
cell voltage. The IC also verifies that V
V
1.95V. If V
if V
is described in more detail below. Once adequate voltage
conditions exist for charging, READY is asserted.
If the voltage between V
LTC4011 is paused. If V
2.85V, the LTC4011 verifies that the sensed temperature is
between 5°C and 45°C. If these temperature limits are not
met or if its own die temperature is too high, the LTC4011
will indicate a fault and not allow charging to begin. If V
is greater than 2.85V, battery temperature related charge
qualification, monitoring and termination are disabled.
Once charging is fully qualified, precharge begins (unless
the LTC4011 is paused). In that case, the V
monitored for further control. The charge status indicators
and PWM outputs remain inactive until charging begins.
Charge Monitoring
The LTC4011 continues to monitor important voltage and
temperature parameters during all charging states. If the
DC input is removed, charging stops and the shutdown
state is entered. If V
below 350mV, charging stops and the LTC4011 returns
to the charge qualification state. If V
charging stops and the IC enters the fault state. If an external
thermistor indicates sensed temperature is beyond a range
of 5°C to 60°C, or the internal die temperature exceeds an
internal thermal limit, charging is suspended, the charge
timer is paused and the LTC4011 indicates a fault condition.

CC
CDIV
CC
CELL
and BAT is reduced to a very low level.
is 510mV above BAT and V
to GND to allow measurement of the average single-
is above 1.95V, the fault state is entered, which
CELL
RT
voltage for temperature sensing, and switches
is below 350mV, no charging will occur, and
CC
(Refer to Figure 1)
drops below 4.25V or V
TEMP
CC
TEMP
(Pin 18). In shutdown all status
and GND is below 200mV, the
is above 200mV but below
CELL
CC
is between 350mV and
, the LTC4011 exits
CC
CELL
is at or above 4.2V,
exceeds 1.95V,
TEMP
CELL
pin is
drops
TEMP
Normal charging resumes from the previous state when
the sensed temperature returns to a satisfactory range. In
addition, other battery faults are detected during specific
charging states as described below.
Precharge State
If the initial voltage on V
enters the precharge state and enables the PWM current
source to trickle charge using one-fifth the programmed
charge current. The CHRG status output is active during
precharge. The precharge state duration is limited to
t
period programmed with the TIMER pin. If sufficient V
voltage cannot be developed in this length of time, the fault
state is entered, otherwise fast charge begins.
Fast Charge State
If adequate average single-cell voltage exists, the LTC4011
enters the fast charge state and begins charging at the
programmed current set by the external current sense
resistor connected between the SENSE and BAT pins.
The CHRG status output is active during fast charge. If
V
processing begins immediately. Otherwise –∆V termination
is disabled for a stabilization period of t
case, the LTC4011 makes another fault check at t
requiring the average cell voltage to be above 1.22V. This
ensures the battery pack is accepting a fast charge. If
V
entered. Fast charge state duration is limited to t
the fault state is entered if this limit is exceeded.
Charge Termination
Fast charge termination parameters are dependent upon
the battery chemistry selected with the CHEM pin. Voltage-
based termination (–∆V) is always active after the initial
voltage stabilization period. If an external thermistor network
is present, chemistry-specific limits for ∆T/∆t (rate of tem-
perature rise) are also used in the termination algorithm.
Temperature-based termination, if enabled, becomes active
as soon as the fast charge state is entered. Successful
charge termination requires a charge rate between C/2 and
2C. Lower rates may not produce the battery voltage and
temperature profile required for charge termination.
MAX
CELL
CELL
/12 minutes, where t
is initially above 1.325V, voltage-based termination
is not above this voltage threshold, the fault state is
CELL
MAX
is below 900mV, the LTC4011
is the maximum fast charge
MAX
/12. In that
MAX
MAX
CELL
4011fb
/12,
and