Datasheet

MAX8819A/MAX8819B/MAX8819C
PMIC with Integrated Chargers and Smart
Power Selector in a 4mm x 4mm TQFN
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The step-down regulator power inputs are critical dis-
continuous current paths that require careful bypass-
ing. In the PCB layout, place the step-down converter
input bypass capacitors as close as possible to each
pair of switching converter power input pins (PV_ to
PG_) to minimize parasitic inductance. If making con-
nections to these capacitors through vias, be sure to
use multiple vias to ensure that the layout does not
insert excess inductance or resistance between the
bypass capacitor and the power pins.
The input capacitor must meet the input ripple current
requirement imposed by the step-down converter.
Ceramic capacitors are preferred due to their low ESR
and resilience to power-up surge currents. Choose the
input capacitor so that its temperature rise due to input
ripple-current does not exceed approximately +10°C.
For a step-down DC-DC converter, the maximum input
ripple current is half of the output current. This maxi-
mum input ripple current occurs when the step-down
converter operates at 50% duty factor (V
IN
= 2 x V
OUT
).
Bypass PV13 to PG1 and PG3 with a 4.7μF ceramic
capacitor. If REG2 is required, bypass PV2 to PG2 with
a 2.2μF capacitor. Use capacitors that maintain their
capacitance over temperature and DC bias. Ceramic
capacitors with an X7R or X5R temperature characteris-
tic generally perform well. The capacitor voltage rating
should be 6.3V or greater.
Step-Down Output Capacitors
The output capacitance keeps output ripple small and
ensures control-loop stability. The output capacitor must
have low impedance at the switching frequency.
Ceramic, polymer, and tantalum capacitors are suitable
with ceramic exhibiting the lowest ESR and lowest high-
frequency impedance. The MAX8819A/MAX8819B
require at least 10μF of output capacitance. The
MAX8819C requires ar least 22μF of output capacitance.
As the case sizes of ceramic surface-mount capacitors
decreases, their capacitance vs. DC bias voltage char-
acteristic becomes poor. Due to this characteristic, it is
possible for 0805 capacitors to perform well while 0603
capacitors of the same value may not. The MAX8819A/
MAX8819B require a nominal output capacitance of
10μF, however, after their DC bias voltage derating, the
output capacitance must be at least 7.5μF.
Step-Down Inductor
Choose the step-down converter inductance to be
4.7μH. The minimum recommended saturation current
requirement is 700mA. In PWM mode, the peak induc-
tor currents are equal to the load current plus one half
of the inductor ripple current. See Table 3 for suggested
inductors.
MANUFACTURER SERIES
INDUCTANCE
(µH)
ESR
(mΩ)
CURRENT RATING
(mA)
DIMENSIONS
(mm)
CDRH2D11HP 4.7 190 750 3.0 x 3.0 x 1.2 = (10.8mm)
3
Sumida
CDH2D09 4.7 218 700 3.0 x 3.0 x 1.0= (9.0mm)
3
NR3012 4.7 130 770 3.0 x 3.0 x 1.2 = (10.8mm)
3
Taiyo Yuden
NR3010 4.7 190 750 3.0 x 3.0 x 1.0 = (9.0mm)
3
VLF3012 4.7 160 740 2.8 x 2.6 x 1.2 = (8.7mm)
3
TDK
VLF3010 4.7 240 700 2.8 x 2.6 x 1.0 = (7.3mm)
3
TOKO DE2812C 4.7 130 880 3.0 x 2.8 x 1.2 = (10.8mm)
3
MIPF2520 4.7 110 1100 2.5 x 2.0 x 1.0 = (5mm)
3
FDK
MIPF2016 4.7 160 900 2.0 x 1.6 x 1.0 = (3.2mm)
3
Table 3. Suggested Inductors