MAX846AEEE Maxim Integrated Products, MAX846AEEE Datasheet - Page 6

• Manufacturer Part Number: MAX846AEEE
• Description: Battery Management Multichemistry Bat Charger System
• Manufacturer: Maxim Integrated Products

Specifications of MAX846AEEE

• Battery Type: Li-Ion, Li-Polymer, NiCd, NiMH
• Output Voltage: 3.3 V
• Operating Supply Voltage: 3.7 V to 20 V
• Supply Current: 5 mA
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Package / Case: QSOP-16
• Mounting Style: SMD/SMT

Cost-Saving Multichemistry
Battery-Charger System
The MAX846A battery-charging controller combines
three functional blocks: a 3.3V precision, low-dropout
linear regulator (LDO), a precision voltage reference,
and a voltage/current regulator (Figure 1).
The LDO regulator output voltage (VL) is two times the
internal reference voltage; therefore, the reference and
LDO track. VL delivers up to 20mA to an external load
and is short-circuit protected. The power-good output
(PWROK) provides microcontroller (µC) reset and
charge-current inhibition.
6
______________________________________________________________Pin Description
_______________Detailed Description
PIN
_______________________________________________________________________________________
10
11
12
13
14
15
16
1
2
3
4
5
6
7
8
9
PWROK
CELL2
NAME
PGND
DCIN
OFFV
BATT
VSET
GND
CCV
ISET
CS+
DRV
CCI
CS-
ON
VL
Supply Input from External DC Source. 3.7V ≤ V
3.3V, 20mA, 1% Linear-Regulator Output. VL powers the system µC and other components. Bypass to
GND with a 4.7µF tantalum or ceramic capacitor.
Current-Regulation-Loop Compensation Pin. Connect a compensation capacitor (typically 10nF) from
CCI to VL.
Ground
Voltage-Regulation-Loop Compensation Pin. Connect a compensation capacitor (typically 10nF) from
CCV to VL.
Float-Voltage Reference-Adjust Input. Leave VSET open for a 4.2V default. See the Applications
Information section for adjustment information.
Current-Set Input/Current-Monitor Output. ISET sets the current-regulation point. Connect a resistor
from ISET to GND to monitor the charging current. ISET voltage is regulated at 1.65V by the current-
regulation loop. To adjust the current-regulation point, either modify the resistance from ISET to ground
or connect a fixed resistor and adjust the voltage on the other side of the resistor (Figure 5). The
transconductance of the current-sense amplifier is 1mA/V.
Logic Input that disables the voltage-regulation loop. Set OFFV high for NiCd or NiMH batteries.
Open-Drain, Power-Good Output to µC. PWROK is low when VL is less than 3V. The reset timeout peri-
od can be set externally using an RC circuit (Figure 3).
Digital Input. CELL2 programs the number of Li-Ion cells to be charged. A high level equals two cells; a
low level equals one cell.
Charger ON/OFF Input. When low, the driver section is turned off and I
always active.
Battery Input. Connect BATT to positive battery terminal.
Current-Sense Amplifier High-Side Input. Connect CS+ to the sense resistor’s power-source side. The
sense resistor may be placed on either side of the pass transistor.
Current-Sense Amplifier Low-Side Input. Connect CS- to the sense resistor’s battery side.
Power Ground
External Pass Transistor (P-channel MOSFET or PNP) Base/Gate Drive Output. DRV sinks current only.
Linear Regulator
The precision internal reference provides a voltage to
accurately set the float voltage for lithium-ion (Li-Ion)
battery charging. The reference output connects in
series with an internal, 2%-accurate, 20kΩ resistor. This
allows the float voltage to be adjusted using one exter-
nal 1% resistor (R
(Figure 4). The float-voltage accuracy is important for
battery life and to ensure full capacity in Li-Ion batter-
ies. Table 1 shows the accuracies attainable using the
MAX846A.
FUNCTION
DCIN
≤ 20V.
VSET
) to form a voltage divider
BATT
<1µA. The VL regulator is
Voltage Reference