Rainbow Electronics MAX1870A - Manual (Page 12)

MAX1870A
Step-Up/Step-Down
Li+ Battery Charger
12 ______________________________________________________________________________________
Typical Operating Characteristics (continued)
(Circuit of Figure 1, V
DCIN
= 16V, CELLS = REFIN, V
CLS =
V
REF
, V
ICTL
= V
REFIN
= 3.3V, T
A
= +25°C, unless otherwise noted.)
Pin Description
PIN NAME FUNCTION
1 LDO
Device Power Supply. Output of the 5.4V linear regulator supplied from DCIN. Bypass LDO to GND with
a 1µF or greater ceramic capacitor.
2 REF 4.096V Voltage Reference. Bypass REF to GND with a 1µF or greater ceramic capacitor.
3 CLS
Source Current-Limit Input. Voltage input for setting the current limit of the input source. See the Setting
the Input Current Limit section.
4, 8 GND Analog Ground
5 CCV
Voltage Regulation Loop Compensation Point. Connect a 10k Ω resistor in series with a 0.01µF capacitor
to GND.
6 CCI Charge-Current Regulation Loop Compensation Point. Connect a 0.01µF capacitor to GND.
7 CCS Input-Current Regulation Loop Compensation Point. Connect a 0.01µF capacitor to GND.
9 REFIN Reference Input. ICTL and VCTL are ratiometric with respect to REFIN for increased accuracy.
10 ASNS
Adapter Sense Output. Logic output is high when input current is greater than 1.5A (using 30m
Ω
sense
resistors and a 10k
Ω
resistor from IINP to GND).
11 VCTL
Charge-Voltage Control Input. Drive VCTL from 0 to V REFIN to adjust the charge voltage from 4V to 4.4V
per cell. See the Setting the Charge Voltage section.
STEP-UP
SWITCHING WAVEFORM
MAX1870Atoc23
0V
D4
10V
0V
CATHODE
D3 ANODE
INDUCTOR CURRENT
4A
V
BATT
(AC-COUPLED)
50mV/div
2A
10V
20V
2.00µs
V IN = 12V
V BATT = 16V
STEP-UP/STEP-DOWN
LIGHT LOAD
MAX1870Atoc24
0V
D4
10V
0V
CATHODE
D3 ANODE
INDUCTOR CURRENT
4A
V BATT
(AC-COUPLED)
50mV/div
2A
10V
20V
2.00µs
V IN = 16V
V BATT = 16V
CHARGE CURRENT = 300mA