MAX17710BEVKIT# Maxim Integrated, MAX17710BEVKIT# Datasheet - Page 11

• Manufacturer Part Number: MAX17710BEVKIT#
• Description: Power Management IC Development Tools
• Manufacturer: Maxim Integrated
• Type: Energy Harvestingr
• Series: MAX17710r

Specifications of MAX17710BEVKIT#

• Product: Power Management Development Tools
• Tool Is For Evaluation Of: MAX17710
• Output Voltage: 1.8 V, 2.3 V, 3.3 V
• Output Current: 625 nA
• Part # Aliases: 90-NC01K#B00

The CHG pin capacitor should be minimized to 0.1FF
for highest charge efficiency. However, when charging
from a high-voltage source, at least 0.22FF is required
for shunt stability.
The LX pin inductor is not required for high-voltage
charge sources. For low-voltage sources, a minimum
inductor value of 0.68FH is required to prevent the maxi-
mum current rating of the LX pin from being exceeded.
Minimum inductor value is calculated as follows:
The boost circuit diode must be a high-speed Schottky,
such as the ZLLS410TA from Diodes Incorporated. The
diode must turn on quickly to clamp the LX pin volt-
age rise at 6.0V or lower when the LX driver turns off.
The LX pin can be damaged if the maximum voltage is
exceeded.
The harvest source capacitor must be a minimum of 70
times larger than the CHG pin capacitor to boost the
charge pin to the maximum charge voltage under worst-
case conditions:
Table 2. Boost Converter External Component Values
Maxim Integrated
High voltage
Low voltage < 10FW
Low voltage > 10FW
High voltage and low
voltage < 10FW
High voltage and low
voltage > 10FW
LX inductor = V
CHARGE SOURCE
APPLICATION
Source capacitor = (4.125V)
FB-ON
850ns/1A = 0.85FH
CHG capacitor
Energy-Harvesting Charger and Protector
CAPACITOR
x t
BOOST-ON
CHG
(µF)
0.22
0.22
0.22
0.1
0.1
Harvest Source Capacitor
2
/(0.485V)
/LX
MINIMUM LX
IMAX
CHG Capacitor
INDUCTOR
Boost Diode
(µH)
0.85
0.85
0.85
0.85
LX Inductor
N/A
= 1.0V x
2
x
RECOMMENDED
LX INDUCTOR
This is the minimum size required for operation. Increasing
the size of the harvest source capacitor beyond this
level improves charge circuit efficiency at extremely low
input power (< 10FW), but care should be taken not to
increase the capacitor so large that the harvest source
cannot overcome the capacitor’s leakage. A maximum
value of 47FF is recommended.
Table 2
Minimum capacitor and inductor values are required for
proper operation of the charge circuit. Recommended
capacitor and inductor values provide optimum charge
efficiency. Components should be sized as close to
the recommended values that the application allows.
Component values below the minimum values, or above
the optimum values, are not recommended.
Charge sources with operational voltages between 1.0V
and 2.0V require boosting, but are too high a voltage to
control the boost circuit efficiently. Under these condi-
tions, a voltage-divider is required to lower the voltage
seen by the FB pin (see
R1 and R2 allows the voltage on the FB pin to transition
properly between the FB
boosting. The value for R2 is calculated as follows:
where V
harvest source.
(µH)
N/A
1.5
1.5
1.5
1.5
lists boost converter external component values.
HARVEST-ON
V
R2 = (V
HARVEST-ON
HARVEST SOURCE
CAPACITOR (µF)
HARVEST-ON
MINIMUM
15.4
15.4
N/A
7.0
7.0
is the operational voltage of the
= F
ON
Figure
BON
and FB
- 1.0V) x 500kI
3). The divider formed by
MAX17710
x (R1 + R2)/R1
OFF
HARVEST SOURCE
CAPACITOR (µF)
RECOMMENDED
thresholds during
FB Divider
15.4
N/A
7.0
47
47
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