DS273 Просмотр технического описания (PDF) - Maxim Integrated
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DS273 Datasheet PDF : 20 Pages
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Cache-Memory Battery-Backup Management IC
Pin Description
PIN
NAME
FUNCTION
1
MARGIN
Voltage-Margining Input. Selects regulation voltage of charging circuit. Connect to the STMR pin through
a resistor-divider.
2
STMR Voltage Safety-Timer Input. Sets timeout period for a charge cycle based on external resistance to AGND.
3
CTG Connect To Ground. Must be connected to AGND externally.
4
AUX Auxiliary. External supply input to switching supply. Connect to system 3.3V supply.
5
CBIAS Internal Regulator Output. Internal supply for the charging circuit generated from the VIN input. Bypass
with a capacitor to AGND.
6
VREG Cache Voltage-Sense Input. Feedback for regulation of the switching circuit voltage. Connect to the
positive side of the switching output load.
7
CIN
Holdup/Bypass Capacitor. Internal supply for the switching regulator. Bypass with a 4.7µF capacitor to
AGND.
8
LX
Switching Node, Backup Supply. Output from the switching regulator. Connect to the switching
regulator’s external coil.
9
SGND Switcher Ground. Ground reference for the switching regulator. Connect to the negative side of the load.
10
AGND Analog Ground. Ground reference for the charging circuit. Connect to the negative side of the battery.
11
REF
Voltage Reference for Backup. 1.238V voltage reference used to set regulation voltage and low-battery-
detection threshold. Connect to AGND through a resistor network.
12
LO_BATT
Low-Battery Detection. Selects the low-battery shutdown threshold of the switching regulator. Connect to
the REF pin through a resistor-divider.
13
DIV
Voltage Divider for Backup. Controls the voltage output level of the switching regulator. Connect to the
REF pin through a resistor-divider.
14
ENS Enable Switcher. Active-low enable for the switching regulator.
15
ENC Enable Charger. Active-high enable for the charging circuit.
16
DONE
Charge-Done Indicator. Open-drain active-low output indicating successful charge completion of the
external cell.
17
FAULT Charger-Fault Indicator. Open-drain active-low output indicating failure during charge of the external cell.
18
CHARGE Charge Indicator. Open-drain active-low output indicating charge of the external cell in progress.
19
CGND2 Charger Ground 2. Ground reference for battery-charging circuit. Connect to negative side of external cell.
20
CGND1 Charger Ground 1. Ground reference for battery-charging circuit. Connect to negative side of external cell.
21
CHG2 High-Current Charger Output 2. Output from the charging circuit. Connect to charging circuit’s external coil.
22
CHG1 High-Current Charger Output 1. Output from the charging circuit. Connect to charging circuit’s external coil.
23
VIN Charge-Supply Input. Connect to 10.8V to 13.2V system supply.
24
CGATE Floating Gate Drive Bypass. Internal supply for the charger gate control. Bypass with a 2.2µF capacitor to VIN.
25
SNS
Current-Sense Input. Feedback for regulator of charger current. Connect a 0.050 sense resistor
between SNS and BATT+.
26
BATT+
Battery Terminal Voltage. Feedback for regulation of charger voltage and supply to switching regulator
during power loss.
27
RSET
Charge-Setting Resistor Intput. Selects CC charge rate for external lithium cell. Connect to AGND
through an external resistor.
28
THM Thermistor Input. Connect to 10k NTC thermistor with good thermal contact to the external lithium cell.
—
EP Exposed Paddle. It is recommended the exposed pad be connected to system ground.
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