MAX1538ETI+T Maxim Integrated Products, MAX1538ETI+T Datasheet - Page 14

• Manufacturer Part Number: MAX1538ETI+T
• Description: IC PWR SOURCE SELECTOR 28-TQFN
• Manufacturer: Maxim Integrated Products

Specifications of MAX1538ETI+T

• Function: Dual Battery Controller
• Battery Type: All Battery Types
• Voltage - Supply: 4.75 V ~ 28 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 28-WFQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Power-Source Selector for
Dual-Battery Systems
The MAX1538 performs power path selection between
an adapter input and two batteries, relieving the host
system from the burden of real-time response to power-
source changes. The integrated selector implements a
fixed break-before-make timer to ensure that power
sources are not connected together and yet the load is
not left unserviced. The MAX1538 monitors battery and
adapter state and presence to determine which source
to select and whether to charge the battery. Logic
inputs CHRG, BATSEL, and RELRN allow the host to
enable/disable charging, select which battery to use,
and impose battery discharge even with adapter pres-
ence. The MAX1538 automatically detects airline
adapters and prevents charging when an airline
adapter is detected. Open-drain logic outputs OUT2,
Table 1. MAX1538 State Table
14
Legend
Adapter
Absent
Absent
Absent
Absent
Absent
Absent
SOURCE STATE
AIR
AIR
AC
AC
AC
AC
AC
AC
______________________________________________________________________________________
AC adapter is present. V
Airline adapter is present. V
External adapter is absent. V
A
X
X
N
X
X
N
N
X
U
U
N
U
X
Battery
N
U
N
N
U
B
X
X
X
X
X
X
Otherwise
Otherwise
N indicates the battery is normal. The battery is normal when it has not tripped the undervoltage latch (5 x
V
U indicates the battery has tripped the undervoltage comparator. An undervoltage battery is detected
when V
Detailed Description
LOGIC INPUTS
1
1
X
X
X
X
X
X
X
X
X
MINV_
X
X
X
X
X
X
X
0
0
1
1
). See the Battery Presence and Undervoltage Detection section.
BAT_
ACDET
goes below 5 x V
X
X
X
X
X
0
1
0
1
0
1
ACDET
ACDET
and V
Otherwise covers all cases not explicitly shown elsewhere in the table.
X indicates don’t care. The output does not depend on any inputs labeled X.
and REVBLK)
(ADPPWR
is below 2V and V
System
and V
AIRDET
On
On
Off
Off
On
On
Off
Off
Off
AIRDET
MINV_
are both above 2V.
MOSFET STATE (See Figure 4)
. See the Battery Presence and Undervoltage Detection section.
are both below 2V.
and DISBAT)
(ADPBLK
Battery
AIRDET
Off
Off
On
On
Off
Off
On
On
Off
OUT1, and OUT0 indicate the state of the selector so
the host can properly respond.
The MAX1538 can be configured for use with a step-
down battery charger, as shown in
step-up/step-down battery charger, as shown in
2. The minimum MAX1538 system requires only six
MOSFETs. The MAX1538 provides relearn-mode sup-
port with the addition of P1. Relearn mode allows the
system to relearn the battery’s capacity without user
intervention.
Table
tions of the MAX1538.
is above 2V.
1 summarizes the possible states and configura-
(CHGA and
BATT A
DISA)
On
Off
On
Off
Off
Off
On
Off
Off
(CHGB and
BATT B
DISB)
Off
On
Off
On
Off
Off
Off
On
Off
1
1
1
1
0
0
0
0
0
1
1
0
0
1
1
0
0
0
Figure
0
1
0
1
0
1
0
1
0
Charge A
Charge B
Relearn A
Relearn B
AC adapter
Airline
Discharge A
Discharge B
Idle
1, or with a
STATE
Figure