Datasheet LT1769 (Analog Devices) - 6
| Hersteller | Analog Devices |
| Beschreibung | Constant-Current/Constant-Voltage 2A Battery Charger with Input Current Limiting |
| Seiten / Seite | 16 / 6 — PIN FUNCTIONS (GN/FE Pin Numbers). GND (Pins 1 to 3, 7, 8, 14, 15, 22, 26 … |
| Dateiformat / Größe | PDF / 243 Kb |
| Dokumentensprache | Englisch |
PIN FUNCTIONS (GN/FE Pin Numbers). GND (Pins 1 to 3, 7, 8, 14, 15, 22, 26 to 28/Pins 4, 5, 14,. 20):. SENSE (Pin 13/Pin 10):
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LT1769
U U U PIN FUNCTIONS (GN/FE Pin Numbers) GND (Pins 1 to 3, 7, 8, 14, 15, 22, 26 to 28/Pins 4, 5, 14,
this function is not used, the resistor and capacitor on
20):
Ground Pins. Must be connected to expanded PC COMP1 pin, shown on the Figure 1 circuit, are not needed. lands for proper heat sinking. See Applications Informa-
SENSE (Pin 13/Pin 10):
Current Amplifier CA1 Input. tion section for details. Sensing can be at either terminal of the battery.
SW (Pin 4/Pin 1):
Switch Output. The Schottky catch
SPIN (Pin 16/Pin 11):
This pin is for the current amplifier diode must be placed with very short lead length in close CA1 bias. It must be connected to R proximity to SW pin and GND. S1 as shown in the 2A Lithium Battery Charger (Figure 1).
BOOST (Pin 5/Pin 2):
This pin is used to bootstrap and
BAT (Pin 17/Pin 12):
Current Amplifier CA1 Input. drive the switch power NPN transistor to a low on-voltage for low power dissipation. In Figure 1, V
COMP2 (Pin 18):
This is also a compensation node for BOOST = VCC + VBAT when switch is on. For lowest IC power dissipation, amplifier CL1. Voltage on this pin rises to 2.8V at input connect boost diode D1 to a 3V to 6V at 30mA voltage adapter current limit and/or at constant-voltage charging. source (see Figure 10).
UVOUT (Pin 19/Pin 13):
This is an open-collector output for
UV (Pin 6/Pin 3):
Undervoltage Lockout Input. The rising undervoltage lockout status. It stays low in undervoltage threshold is at 6.7V with a hysteresis of 0.5V. Switching state. With an external pull-up resistor, it goes high at valid stops in undervoltage lockout. When the input supply VCC. Note that the base drive of the open-collector NPN (normally the wall adapter output) to the IC is removed, the comes from CLN pin. UVOUT stays low only when CLN is UV pin must be pulled down to below 0.7V (a 5k resistor higher than 2V. Pull-up current should be kept under 100µA. from adapter output to GND is required) otherwise the
VC (Pin 20/Pin 15):
This is the inner loop control signal for reverse battery current drained by the IC will be approxi- the current mode PWM. Switching starts at 0.7V. In mately 200µA instead of 3µA. Do not leave the UV pin normal operation, a higher VC corresponds to higher floating. When connected to VIN with no resistor divider, charge current. A capacitor of at least 0.33µF to GND the built-in 6.7V undervoltage lockout will be effective. filters out noise and controls the rate of soft start. To stop
OVP (Pin 9/Pin 6):
This is the input to amplifier VA with a switching, pull this pin low. Typical output current is 30µA. threshold of 2.465V. Typical bias current is about 3nA out
PROG (Pin 21/Pin 16):
This pin is for programming the of this pin. For charging lithium-ion batteries, VA monitors charge current and for system loop compensation. During the battery voltage and reduces charging when battery normal operation, VPROG stays close to 2.465V. If it is voltage reaches the preset value. If it is not used, the OVP shorted to GND switching will stop. When a microproces- pin should be grounded. sor controlled DAC is used to program charge current, it
CLP (Pin 10/Pin 8):
This is the positive input to the input must be capable of sinking current at a compliance up to current limit amplifier CL1. The threshold is set at 100mV. 2.465V. When used to limit supply current, a filter is needed to filter
VCC1, VCC2, VCC3 (Pins 23 to 25/Pins 17 to 19):
Input out the 200kHz switching noise. Supply. For good bypass, a low ESR capacitor of 15µF or
CLN (Pin 11/Pin 7):
This is the negative input to the input higher is required, with the lead length kept to a minimum. current limit amplifier CL1. VCC should be between 8V and 28V and at least 3V higher than V
COMP1 (Pin 12/Pin 9):
This is the compensation node for BAT. Undervoltage lockout starts and switching stops when V the input current limit amplifier CL1. At input adapter CC goes below 7V typical. Note that there is an internal parasitic diode from SW pin to V current limit, this node rises to 1V. By forcing COMP1 low CC pin. Do not force V with an external transistor, amplifier CL1 will be defeated CC below SW by more than 0.7V with battery present. All three V (no adapter current limit). COMP1 can source 200µA. If CC pins should be shorted together close to the pins. 1769fa 6
U U U PIN FUNCTIONS (GN/FE Pin Numbers) GND (Pins 1 to 3, 7, 8, 14, 15, 22, 26 to 28/Pins 4, 5, 14,
this function is not used, the resistor and capacitor on
20):
Ground Pins. Must be connected to expanded PC COMP1 pin, shown on the Figure 1 circuit, are not needed. lands for proper heat sinking. See Applications Informa-
SENSE (Pin 13/Pin 10):
Current Amplifier CA1 Input. tion section for details. Sensing can be at either terminal of the battery.
SW (Pin 4/Pin 1):
Switch Output. The Schottky catch
SPIN (Pin 16/Pin 11):
This pin is for the current amplifier diode must be placed with very short lead length in close CA1 bias. It must be connected to R proximity to SW pin and GND. S1 as shown in the 2A Lithium Battery Charger (Figure 1).
BOOST (Pin 5/Pin 2):
This pin is used to bootstrap and
BAT (Pin 17/Pin 12):
Current Amplifier CA1 Input. drive the switch power NPN transistor to a low on-voltage for low power dissipation. In Figure 1, V
COMP2 (Pin 18):
This is also a compensation node for BOOST = VCC + VBAT when switch is on. For lowest IC power dissipation, amplifier CL1. Voltage on this pin rises to 2.8V at input connect boost diode D1 to a 3V to 6V at 30mA voltage adapter current limit and/or at constant-voltage charging. source (see Figure 10).
UVOUT (Pin 19/Pin 13):
This is an open-collector output for
UV (Pin 6/Pin 3):
Undervoltage Lockout Input. The rising undervoltage lockout status. It stays low in undervoltage threshold is at 6.7V with a hysteresis of 0.5V. Switching state. With an external pull-up resistor, it goes high at valid stops in undervoltage lockout. When the input supply VCC. Note that the base drive of the open-collector NPN (normally the wall adapter output) to the IC is removed, the comes from CLN pin. UVOUT stays low only when CLN is UV pin must be pulled down to below 0.7V (a 5k resistor higher than 2V. Pull-up current should be kept under 100µA. from adapter output to GND is required) otherwise the
VC (Pin 20/Pin 15):
This is the inner loop control signal for reverse battery current drained by the IC will be approxi- the current mode PWM. Switching starts at 0.7V. In mately 200µA instead of 3µA. Do not leave the UV pin normal operation, a higher VC corresponds to higher floating. When connected to VIN with no resistor divider, charge current. A capacitor of at least 0.33µF to GND the built-in 6.7V undervoltage lockout will be effective. filters out noise and controls the rate of soft start. To stop
OVP (Pin 9/Pin 6):
This is the input to amplifier VA with a switching, pull this pin low. Typical output current is 30µA. threshold of 2.465V. Typical bias current is about 3nA out
PROG (Pin 21/Pin 16):
This pin is for programming the of this pin. For charging lithium-ion batteries, VA monitors charge current and for system loop compensation. During the battery voltage and reduces charging when battery normal operation, VPROG stays close to 2.465V. If it is voltage reaches the preset value. If it is not used, the OVP shorted to GND switching will stop. When a microproces- pin should be grounded. sor controlled DAC is used to program charge current, it
CLP (Pin 10/Pin 8):
This is the positive input to the input must be capable of sinking current at a compliance up to current limit amplifier CL1. The threshold is set at 100mV. 2.465V. When used to limit supply current, a filter is needed to filter
VCC1, VCC2, VCC3 (Pins 23 to 25/Pins 17 to 19):
Input out the 200kHz switching noise. Supply. For good bypass, a low ESR capacitor of 15µF or
CLN (Pin 11/Pin 7):
This is the negative input to the input higher is required, with the lead length kept to a minimum. current limit amplifier CL1. VCC should be between 8V and 28V and at least 3V higher than V
COMP1 (Pin 12/Pin 9):
This is the compensation node for BAT. Undervoltage lockout starts and switching stops when V the input current limit amplifier CL1. At input adapter CC goes below 7V typical. Note that there is an internal parasitic diode from SW pin to V current limit, this node rises to 1V. By forcing COMP1 low CC pin. Do not force V with an external transistor, amplifier CL1 will be defeated CC below SW by more than 0.7V with battery present. All three V (no adapter current limit). COMP1 can source 200µA. If CC pins should be shorted together close to the pins. 1769fa 6