DS2712 Maxim Integrated Products, Inc., DS2712 Datasheet - Page 8

• Manufacturer Part Number: DS2712
• Description: Loose Cell Nimh Chargers
• Manufacturer: Maxim Integrated Products, Inc.

Parallel Charge Configuration
The parallel configuration supports two slot stand-alone chargers. Charge pulses are fed alternately to each cell
under the control of the CC1 and CC2 pins so the charge regimes occur in parallel. The duty cycle on CC1 and
CC2 are independent of one another. Transitions from precharge to fast charge, fast charge to top-off, and top-off
to maintenance occur independently for each cell.
The configuration shown in Figure 4 is for charging two cells with the current-sense feedback regulating the charge
source to 2A (RSNS = 0.068W). The effective charge current for each cell is 2A x 0.484 = 0.968A. A charger with
battery holders designed to accept either AA or AAA cell sizes can be constructed with the current-sense
resistance split between two separate resistors so each cell type (AA or AAA) is charged at a different rate.
Mechanical design of the holders is required to prevent insertion of more than one cell in each slot. The holder
design must also prevent electrical contact with reverse polarity insertion.
Figure 4. PARALLEL CONFIGURATION WITH EXTERNAL CURRENT
REGULATION
The series or parallel charge configuration is programmed by strapping LED2 in the low, high, or high-Z (float) state
during power-up. In this example and the following one, the parallel charge mode is selected by pulling LED2 pin
high during power-up. This is accomplished in this example by the LED and 270W resistor. In applications where
only one LED is used, a 100kW pullup resistor is recommended. See Table 3. CHARGE MODE SELECTION on
page 13 for additional configuration programming information.
ICHG
GND
+5V
IFB
10K
FCX718
100
270
270
10K
FCX718
100
CC1
CC2
LED1
VSS
LED2
CSOUT
VN1
VN0
DS2711/12
RSNS
0.068
8 of 14
DMSEL
THM2
THM1
CTST
VDD
TMR
VP2
VP1
75K
0.1
100K
103AT-2
10K
x2
x2