maxlength
<div class="search-form">
<form action="<?=$arResult["FORM_ACTION"]?>">
<table border="0" cellspacing="0" cellpadding="2" align="center">
<tr>
<td align="center"><?if($arParams["USE_SUGGEST"] === "Y"):?><?$APPLICATION->IncludeComponent(
"bitrix:search.suggest.input",
"",
array(
"NAME" => "q",
"VALUE" => "",
"INPUT_SIZE" => 15,
"DROPDOWN_SIZE" => 10,
),
$component, array("HIDE_ICONS" => "Y")
);?><?else:?><input type="text" name="q" value="" size="15" maxlength="500" /><?endif;?></td>
</tr>
<tr>
<td align="right"><input name="s" type="submit" value="<?=GetMessage("BSF_T_SEARCH_BUTTON");?>" /></td>
</tr>
</table>
</form>
</div>