Datasheet LTC1960 (Analog Devices) - 9

link to page 28 link to page 12 link to page 28 LTC1960
PIN FUNCTIONS (G/UHF) TGATE (Pin 32/Pin 21):
Drives the top external MOSFET
DCIN (Pin 29/Pin 18):
Supply. External DC power source. of the battery charger buck converter. A 1µF bypass capacitor should be connected to this pin as
SCH1 (Pin 33/Pin 22), SCH2 (Pin 36/Pin 25):
Charger close as possible. No series resistance is allowed, since MUX N-Channel Switch Source Returns. These two pins the adapter current limit comparator input is also this pin. are connected to the sources of the back-to-back switch
Internal Power Supply Pins
pairs, Q3/Q4 and Q9/Q10 (see Typical Application on back
GND (Pin 16/Pin 4, Pin 10, Pin 26, Pin 39):
Ground for page of data sheet), respectively. A small pull-down cur- Low Power Circuitry. rent source returns these nodes to 0V when the switches are turned off.
PGND (Pin 26/Pin 15):
High Current Ground Return for BGATE Driver.
GCH1 (Pin 34/Pin 23), GCH2 (Pin 35/Pin 24):
Charger MUX N-Channel Switch Gate Drives. These two pins drive
VCC (Pin 28/Pin 17):
Internal Regulator Output. Bypass the gates of the back-to-back switch pairs, Q3/Q4 and Q9/ this output with at least a 2µF to 4.7µF capacitor. Do not Q10, between the charger output and the two batteries. use this regulator output to supply more than 1mA to external circuitry.
External Power Supply Pins Digital Interface Pins VPLUS (Pin 1/Pin 27):
Supply. The VPLUS pin is connected via four internal diodes to the DCIN, SCN, BAT1, and BAT2
SSB (Pin 18/Pin 6):
SPI Slave Select Input. Active low. pins. Bypass this pin with a 1µF to 2µF capacitor. TTL levels. This signal is low when clocking data to/from the LTC1960.
BAT1 (Pin 3/Pin 29), BAT2 (Pin 2/Pin 28):
These two pins are the inputs from the two batteries for power to
SCK (Pin 19/Pin 7):
Serial SPI Clock. TTL levels. the LTC1960 and to provide voltage feedback to the bat-
MISO (Pin 20/Pin 8):
SPI Master-In-Slave-Out Output, tery charger. Open Drain. Serial data is transmitted from the LTC1960,
LOPWR (Pin 12/Pin 38):
LOPWR Comparator Input from when SSB is low, on the falling edge of SCK. TTL levels. SCN External Resistor Divider to GND. If the voltage at A 4.7k pull-up resistor is recommended. LOPWR is lower than the LOPWR comparator threshold,
MOSI (Pin 21/Pin 9):
SPI Master-Out-Slave-In Input. Serial then system power has failed and power is autonomously data is transmitted to the LTC1960, when SSB is low, on switched to a higher voltage source, if available. See the rising edge of SCK. TTL levels. PowerPath section of LTC1960 operation.
GND (Exposed Pad Pin 39, UHF Package Only):
Ground.
DCDIV (Pin 17/Pin 5):
External DC Source Comparator Must be soldered to the PCB ground for rated thermal Input from DCIN External Resistor Divider to GND. If the performance. voltage at DCDIV is above the DCDIV comparator thresh- old, then the DC bit is set and the wall adapter power is considered to be adequate to charge the batteries. If DCDIV rises more than 1.8V above VCC, then all of the PowerPath switches are latched off until all power is removed. A capacitor from DCDIV to GND is recommended to prevent noise-induced false emergency turn-off conditions from being detected. Refer to “Fast PowerPath Turn-Off” in the Operation section and the Typical Application on the back page of this data sheet. Rev. C For more information www.analog.com 9 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Test Circuit Timing Diagram Operation Applications Information Package Description Revision History Typical Application Related Parts