DS2715Z+ Maxim Integrated Products, DS2715Z+ Datasheet - Page 8

• Manufacturer Part Number: DS2715Z+
• Description: IC NIMH CHARGER 16-SOIC
• Manufacturer: Maxim Integrated Products

Specifications of DS2715Z+

• Function: Charge Management
• Battery Type: Nickel Metal Hydride (NiMH)
• Voltage - Supply: 4.5 V ~ 16 V
• Operating Temperature: -20°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 16-SOIC (0.154", 3.90mm Width)
• Operating Supply Voltage: 16.5 V
• Supply Current: 1.3 mA
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 20 C
• Charge Safety Timers: Yes
• Mounting Style: SMD/SMT
• Temperature Monitoring: Yes
• Uvlo Start Threshold: 3.9 V
• Uvlo Stop Threshold: 35 mV
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

PRESENCE
The DS2715 enters the PRESENCE state whenever V
source is present, but no cell is available to charge. The DS2715 will remain in the PRESENCE state until a cell is
inserted into the circuit causing the voltage on V
valid charging range between 0°C and 45°C (T
resistor values). If both of these conditions are met, the DS2715 will enter PRE-CHARGE. If cells are inserted, but
the temperature is outside the valid charging range, the DS2715 will remain in the PRESENCE state until the cell
temperature falls within the valid charging range.
PRE-CHARGE
The DS2715 enters the PRECHARGE state when a valid cell voltage is applied to V
as measured by the DS2715 thermistor circuit is within the valid charging range. PRE-CHARGE mode has a 4
second filter to suppress noise on V
state. The DS2715 precharges the cell by regulating the voltage drop across the sense resistor to -33mV (V
linear mode or -29mV (V
resistor is referenced to the polarity relationship indicated by the SNS+ and SNS- pins on the device. Precharging
will last until the cell voltage measured by V
the FAST-CHARGE state. If the cell voltage does not exceed V
exceeds 50°C at any time during PRECHARGE, the DS2715 enters the FAULT state. If at any time during
PRECHARGE the voltage on V
removed and returns to the PRESENCE state.
FAST-CHARGE
In FAST-CHARGE mode, the DS2715 regulates the voltage across the sense resistor to -121mV (V
mode or about -107mV (V
During FAST-CHARGE, the DS2715 constantly measures the rate of change of the cell temperature (dT/dt). When
the cell pack’s dT/dt exceeds 0.5°C per minute (T
changes in the cell temperature caused by charge initiation for the first 4.3 minutes (t
overcharge protection, the DS2715 will terminate FAST-CHARGE and enter TOPOFF based on a time delay set
by the external resistor on the R
anywhere from 30 minutes up to 6 hours. If the cell temperature exceeds 50°C at any time during FAST-CHARGE,
the DS2715 enters the DONE state. If at any time during FAST-CHARGE the voltage on V
(V
TOPOFF
In TOPOFF mode, the DS2715 regulates the voltage across the sense resistor to -33mV (V
29mV (V
reset and restarted with a time-out period of one-half (one-quarter for DS2715B) the fast-charge duration. When
the charge timer expires or if the measured temperature exceeds 50°C, the charger enters the DONE state.
DONE/Maintenance
The DS2715 enters the DONE state whenever the charge completes normally or if the measured cell temperature
exceeds 50°C during the charge. While in the done state V
regulated charging of the cell pack and LED is driven high-impedance to indicate no charging is taking place. A
maintenance charge can be applied to the cells by providing a one-way resistive path from the charge source to the
cell pack bypassing the regulating transistor. See the example in the circuit of Figure 3. The DS2715 remains in the
DONE state until a cell voltage greater than 1.65V (V
pin is floated (see SUSPEND function), or DISCHARGE mode is entered.
FAULT
The DS2715 enters FAULT if PRECHARGE is unable to charge the cell above 1.0V (V
PRECHARGE timeout (t
is high impedance and LED1 output pulses to indicate the fault condition. The DS2715 remains in FAULT until a
cell voltage greater than 1.65V (V
DS2715 then enters the PRESENCE state and waits for the next cell insertion.
SUSPEND
OPEN
), the DS2715 determines that the cell pack has been removed and returns to the PRESENCE state.
TO
+ 0.5 x V
HYS-TO
PC-TO
TO
) in comparator mode. LED1 indicates the cell pack is being charged. The charge timer is
FC
+ 0.5 x V
) or if the cell temperature exceeds 50°C during PRECHARGE. In the fault state, V
+ 0.5 x V
BATT
T
OPEN
BATT
HYS-TO
exceeds 1.65V (V
pin. This resistor value can set the secondary charge termination delay to
HYS-FC
) is detected on V
caused by cell insertion that may cause a premature return to PRESENCE
) in comparator mode. The polarity of the voltage drop across the sense
) in comparator mode. LED1 indicates the cell pack is being charged.
BATT
THM-MIN
BATT
TERM
exceeds 1.0V (V
OPEN
to fall below 1.55V (V
) the DS2715 enters the TOPOFF state. The DS2715 ignores
8 of 17
and T
OPEN
DD
) is detected on V
BATT
), the DS2715 determines that the cell pack has been
> V
THM-MAX
CH
UVLO
indicating the cell pack has been removed. The
BATT
is driven to high impedance to prevent further
LB
when used with recommended thermistor and
and V
within 30 minutes or if the cell temperature
> V
LB
BATT
BATT
DET
), at which time the DS2715 will enter
) and the cell temperature is inside a
> V
indicating cell pack removal, the Rt
OPEN
BATT
indicating that the charge
LB
and the cell temperature
) before the 30 minute
TO
BLANK
) in linear mode or -
BATT
). As secondary
exceeds 1.65V
FC
) in linear
TO
) in
CH