MAX1586A Datasheet, PDF (28/32 Pages) Maxim Integrated Products – High-Efficiency, Low-IQ PMICs with Dynamic Core for PDAs and Smart Phones

High-Efficiency, Low-I_Q PMICs with
Dynamic Core for PDAs and Smart Phones
active. In addition to biasing V7, the rechargeable bat-
tery may be required to also power other supplies.
Rechargeable NiMH Backup Battery
In some systems, a NiMH battery may be desired for
backup. Usually this requires multiple cells because
the typical NiMH cell voltage is only 1.2V. By adding a
small DC-DC converter (MAX1724), the low-battery
voltage is boosted to 3V to bias BKBT (Figure 8). The
DC-DC converter’s low operating current (1.5µA typ)
allows it to remain on constantly so the 3V BKBT bias is
always present. A resistor and diode trickle charge the
NiMH cell when the main power is present.
PC Board Layout and Routing
Good PC board layout is important to achieve optimal
performance. Conductors carrying discontinuous cur-
rents and any high-current path should be made as
short and wide as possible. A separate low-noise
ground plane containing the reference and signal
grounds should connect to the power-ground plane at
only one point to minimize the effects of power-ground
currents. Typically, the ground planes are best joined
right at the IC.
Keep the voltage feedback network very close to the
IC, preferably within 0.2in (5mm) of the FB_ pin. Nodes
with high dV/dt (switching nodes) should be kept as
small as possible and should be routed away from
high-impedance nodes such as FB_. Refer to the
MAX1586 or MAX1587 evaluation kit data sheets for a
full PC board example.
MAX1586
MAX1587 ^PV3
TO BATT
LX3
STEP-DOWN
PWM
REG3
PG3
FB3
V3
VCC_CORE
R24
R24 VALUES:
R24 = 3.32kΩ, V3: 0.73V TO 1.55V, 26mV/STEP
R24 = 5.11kΩ, V3: 0.75V TO 1.60V, 27mV/STEP
R24 = 7.5kΩ, V3: 0.78V TO 1.65V, 28mV/STEP
R25
100kΩ
Figure 9. Adding R24 and R25 to Increase Core Voltage
Programming Range
Increasing V3 (VCC_CORE) Voltage Range
The programmable V3 output voltage range can be
increased by adding two resistors as shown in Figure 9.
Chip Information
TRANSISTOR COUNT: 13,958
PROCESS: BiCMOS
Pin Configurations
TOP VIEW
FB1 1
BKBT 2
V7 3
V1 4
SLPIN 5
V2 6
FB2 7
CC2 8
POK 9
SCL 10
MAX1587AETL
30 RSO
29 SRAD
28 PV3
27 LX3
26 PG3
25 V5
24 IN45
23 V4
22 ON45
21 ON2
LB1 1
CC1 2
FB1 3
BKBT 4
V7 5
V1 6
SLPIN 7
V2 8
FB2 9
CC2 10
POK ¹¹
SCL 12
MAX1586AETM
MAX1586BETM
36 RSO
35 SRAD
34 _ON3
33 PV3
32 LX3
31 PG3
30 _ON5
29 V5
28 IN45
27 V4
26 ON4
25 ON2
THIN QFN
6mm × 6mm
THIN QFN
7mm × 7mm
28 ______________________________________________________________________________________