Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Calculation/Engineering.php
public static function HEXTOBIN($x, $places = null)
    {
        $x = Functions::flattenSingleValue($x);
        $places = Functions::flattenSingleValue($places);

        if (is_bool($x)) {
            return Functions::VALUE();
        }
        $x = (string) $x;
        if (strlen($x) > preg_match_all('/[0123456789ABCDEF]/', strtoupper($x), $out)) {
            return Functions::NAN();
        }

        return self::DECTOBIN(self::HEXTODEC($x), $places);
    }
public static function HEXTOBIN($x, $places = null)
    {
        $x = Functions::flattenSingleValue($x);
        $places = Functions::flattenSingleValue($places);

        if (is_bool($x)) {
            return Functions::VALUE();
        }
        $x = (string) $x;
        if (strlen($x) > preg_match_all('/[0123456789ABCDEF]/', strtoupper($x), $out)) {
            return Functions::NAN();
        }

        return self::DECTOBIN(self::HEXTODEC($x), $places);
    }
HEXTOBIN.

Return a hex value as binary.

Excel Function:
HEX2BIN(x[,places])

@category Engineering Functions

@param string $x the hexadecimal number you want to convert.
Number cannot contain more than 10 characters.
The most significant bit of number is the sign bit (40th bit from the right).
The remaining 9 bits are magnitude bits.
Negative numbers are represented using two's-complement notation.
If number is negative, HEX2BIN ignores places and returns a 10-character binary number.
If number is negative, it cannot be less than FFFFFFFE00,
and if number is positive, it cannot be greater than 1FF.
If number is not a valid hexadecimal number, HEX2BIN returns the #NUM! error value.
If HEX2BIN requires more than places characters, it returns the #NUM! error value.
@param int $places The number of characters to use. If places is omitted,
HEX2BIN uses the minimum number of characters necessary. Places
is useful for padding the return value with leading 0s (zeros).
If places is not an integer, it is truncated.
If places is nonnumeric, HEX2BIN returns the #VALUE! error value.
If places is negative, HEX2BIN returns the #NUM! error value.

@return string