Background
1.1 Background
The bq2400x series ICs are advanced Li-Ion linear charge management devices for highly integrated and space-limited applications. They combine high-accuracy current and voltage regulation; FET pass-transistor and reverse-blocking Schottky; battery conditioning, temperature, or input-power monitoring; charge termination; charge-status indication; and charge timer in a small, 20-lead TSSOP PowerPAD package.
The bq2400x continuously measures battery temperature using an external thermistor. For safety reasons, the bq2400x inhibits charge until the battery temperature is within the user-defined thresholds. Alternatively, the user can monitor the input voltage to qualify charge. The bq2400x series then charge the battery in three phases: preconditioning, constant current and constant voltage. If the battery voltage is below the internal low-voltage threshold, the bq2400x uses trickle-charge to condition the battery. A preconditioning timer is provided for additional safety. Following preconditioning, the bq2400x applies a constant-charge current to the battery. An external sense-resistor sets the magnitude of the current. The constant-current phase is maintained until the battery reaches the charge-regulation voltage. The bq2400x then transitions to the constant voltage phase. The user can configure the device for cells with either coke or graphite anodes.
Charge is terminated by either of the following methods:
-Maximum time
-Minimum current detection
1.2Performance Specification Summary
This section summarizes the performance specifications of the SLUP051 EVM. Table 1–1 gives the performance specifications of the hubs.
The bq2400x automatically restarts the charge if the battery voltage falls below an internal recharge threshold.
Table 1–1. Performance Specification Summary (One Cell)
| Specification | Test Conditions | Min | Typ | Max | Units |
| | | | | | | |
| Input dc voltage, VDC | | 4.9 | 5.0 | † | V |
| Battery charge current, ICHG | J4 shorted, J3 open | 0.4 | 0.5 | 0.6 | A |
| | | | |
| J3 shorted, J4 open | 0.9 | 1 | 1.1 |
| | | |
| | | | | | | |
| Battery voltage regulation, VREG | J6 set to VCC | 4.15 | 4.20 | 4.25 | V |
| J6 set to GND | 4.05 | 4.1 | 4.15 |
| | | |
| | | | | | | |
| Therm fault | High, TBATMAX | J2 set to Therm | 43 | 48 | 53 | ° C |
| Low, TBATMIN | J2 set to Therm | 0 | 5 | 10 |
| | |
| APG (user defined, see data sheet) | J2 set to APG | | ‡ | | |
| | | | | | |
| Power dissipation, PD | (VI-VO) × Iload | | | 2.3 | W |
†VI, for a single-cell, should not exceed 5.3 VDC for the 1-A charge rate and 7.6 V for the 0.5-A charge rate. (VI is the input voltage to the bq2400x IC, pins 2 and 3. The power supply source voltage, at J1, is 0.1 V larger than VI because of the regulated voltage drop across the current sense resistor, during constant current regulation.)
‡ If J2 is set to APG, then the chip will be disabled when the input is outside of this range: 4.02 V± 0.07 V and 10.76 V ± 0.09 V.
