• ADP1650

• ADP1650CB-EVALZ

The ADP1650 is a very compact, highly efficient, single white LED flash driver for high resolution camera phones that improves picture and video quality in low light environments. The device integrates a programmable 1.5 MHz or 3 MHz synchronous inductive boost converter, an I²C-compatible interface, and a 1500 mA current source. The high switching frequency enables the use of a tiny, 1 mm high, low cost, 1 μH power inductor, and the current source permits LED cathode grounding for thermally enhanced, low EMI, and compact layouts.

The LED driver maximizes efficiency over the entire battery voltage range to maximize the input-power-to-LED-power conversion and to minimize battery current draw during flash events. A programmable dc battery current limit safely maximizes LED current for all LED V_F and battery voltage conditions.

Two independent TxMASK inputs permit the flash LED current and battery current to reduce quickly during a power amplifier current burst. The I²C-compatible interface enables the pro-grammability of timers, currents, and status bit readback for operation monitoring and safety control.

The ADP1650 comes in a compact 12-ball, 0.5 mm pitch WLCSP package and operates within specification over the full −40°C to +125°C junction temperature range.

• Camera-enabled cellular phones and smart phones
• Digital still cameras, camcorders, and PDAs

• Product Page
• ADP1650 Data Sheet Rev B, 02/2011 (pdf 1072kB) (About Data Sheets)

#include <linux/i2c/adp1650.h>
 
static struct adp1650_leds_platform_data adp1650_pdata = {
	.timer_iocfg = 	ADP1650_IOCFG_IO2_HIGH_IMP |
			ADP1650_IOCFG_IO1_TORCH |
			ADP1650_FL_TIMER_ms(500),
 
	.current_set = 	ADP1650_I_FL_mA(900) |
			ADP1650_I_TOR_mA(100),
 
	.output_mode = 	ADP1650_IL_PEAK_2A25 |
			ADP1650_STR_LV_EDGE |
			ADP1650_FREQ_FB_EN |
			ADP1650_OUTPUT_EN |
			ADP1650_STR_MODE_HW |
			ADP1650_STR_MODE_STBY,
 
	.control = 	ADP1650_I_TX2_mA(400) |
			ADP1650_I_TX1_mA(400),
 
	.ad_mode =	ADP1650_DYN_OVP_EN |
			ADP1650_STR_POL_ACTIVE_HIGH |
			ADP1650_I_ILED_2mA75 |
			ADP1650_IL_DC_1A50 |
			ADP1650_IL_DC_EN,
 
	.batt_low =	ADP1650_CL_SOFT_EN |
			ADP1650_I_VB_LO_mA(400) |
			ADP1650_V_VB_LO_3V50,
 
	.gpio_enable = -1,
};

static struct i2c_board_info __initdata board_i2c_board_info[] = {
#if defined(CONFIG_LEDS_ADP1650) || defined(CONFIG_LEDS_ADP1650_MODULE)
	{
		I2C_BOARD_INFO("adp1650", 0x30),
		.platform_data = (void *)&adp1650_pdata,
	},
#endif
};

static int __init board_init(void)
{
	[--snip--]
 
	i2c_register_board_info(0, board_i2c_board_info,
				ARRAY_SIZE(board_i2c_board_info));
	[--snip--]
 
	return 0;
}
arch_initcall(board_init);

Configure kernel with “make menuconfig” (alternatively use “make xconfig” or “make qconfig”)

Device Drivers  --->
	[*] LED Support  ---> 
		--- LED Support
		[*]   LED Class Support
			* LED drivers *

		<--snip-->
		<*>   LED Support for ADP1650 I2C chips
		<--snip-->

The LED class allows control of LEDs from userspace. LEDs appear in /sys/class/leds/. The brightness file will set the brightness of the LED (taking a value 0-255).

For more information read linux/Documentaion/leds-class.txt

brightness

get/set LED brightness (an integer between 0 and 255)

max_brightness

the maximum brightness value.

root:/> cd sys/class/leds/adp1650/

root:/sys/devices/platform/i2c-bfin-twi.0/i2c-0/0-0030/leds/adp1650> ls -l
-rw-r--r--    1 root     root          4096 Jan  5 08:42 brightness
lrwxrwxrwx    1 root     root             0 Jan  5 08:23 device -> ../../../0-0030
-r--r--r--    1 root     root          4096 Jan  5 08:23 max_brightness
drwxr-xr-x    2 root     root             0 Jan  5 08:23 power
lrwxrwxrwx    1 root     root             0 Jan  5 08:23 subsystem -> ../../../../../../../class/leds
-rw-r--r--    1 root     root          4096 Jan  5 08:23 uevent