DocID18265 Rev 8

17/25

AN3319

External component selection

Output current sensing filter

R

s

is placed in the output rail between the I

CTRL_MINUS

and I

CTRL_PLUS

pins.

Its role is to sense the output current (I

OUT

) flowing toward the load. Voltage drop on R

s

is

sensed by the I

CTRL_MINUS

and I

CTRL_PLUS

pins and compared with the 50 mV internal

threshold.

The triangular waveform of the current and noise may cause unexpected triggering of the

50 mV threshold. This can be avoided with a filter such as the one shown below:

Suggested values are:

R

F1

=R

F2

= 1 k

Ω

C

F

= 1 μF

Output protection diode

If the load is not a battery, D

OUT

is required and placed in parallel to the output load. Its role

is to protect the devices in case a PV cell providing I

MP

> 0.5 A is connected when very low

load is connected.

In fact, SPV1040 is supplied by the V

OUT

pin, so in the above condition the device is still off

when the PV cell is connected and a voltage spike can occur damaging the converter and

the battery.

In order to guarantee the best system performance and reliability, D

OUT

should be selected

as follows:

V

BR

> V

OUT_max

V

CL

≤ 5.5 V

D

OUT

must be able to dissipate the following maximum power:

P

max

= I

SC

*V

CL

XSHUT resistor

The XSHUT pin controls SPV1040 turn-on (0.3 V

≤ XSHUT ≤ 5.2 V) or turn-off (XSHUT <

0.3 V).

R

S

50 m V

I

OUT m ax

----------------------

≅

_

AM06707v1

R

S

R

F1

R

F2

C

F

V

OUT

I

CTRL_PLUS

I

CTRL_MINUS

BAT+

V