The LM3559 is a 2-MHz fixed-frequency synchronous boost converter with two 900-mA constant current drivers for high-current white LEDs. The dual high-side current sources allow for grounded cathode LED operation and can be tied together for providing flash currents of up to 1.8 A. An adaptive regulation method ensures the current for each LED remains in regulation and maximizes efficiency.
The LM3559 is controlled via an I2C-compatible interface. Features include: an internal 4-bit ADC to monitor the LED voltage, independent LED current control, a hardware flash enable allowing a logic input to trigger the flash pulse, dual TX inputs which force the flash pulse into a low-current torch mode allowing for synchronization to RF power amplifier events or other high-current conditions, an integrated comparator designed to monitor an NTC thermistor and provide an interrupt to the LED current, an input voltage monitor to monitor low battery conditions, and a flash current scale-back feature that actively monitors the battery voltage and optimizes the flash current during low battery-voltage conditions. Additionally, an active high HWEN input provides a hardware shutdown during system software failures.
The 2-MHz switching frequency, overvoltage protection, and adjustable current limit allow for the use of tiny, low-profile (1-µH or 2.2-µH) inductors and (10-µF) ceramic capacitors. The device is available in a ultra-small 16-pin DSBGA package (total solution size < 26 mm2) and operates over the –40°C to +85°C temperature range.
PART NUMBER | PACKAGE | BODY SIZE (NOM) |
---|---|---|
LM3559 | DSBGA (16) | 1.96 mm × 1.96 mm |
Changes from A Revision (May 2013) to B Revision
Changes from * Revision (May 2013) to A Revision
PIN | TYPE | DESCRIPTION | |
---|---|---|---|
NO. | NAME | ||
A1 | LED1 | Power | High-side current source output for flash LED1 |
A2, B2 | OUT | Power | Step-up DC-DC converter output. Connect a 10-µF ceramic capacitor between this pin and GND. |
A3, B3 | SW | Power | Drain connection for internal NMOS and synchronous PMOS switches |
A4, B4 | GND | Ground | Ground |
B1 | LED2 | Output | High-side current source output for flash LED2 |
C1 | LEDI/NTC | Input/Output | Configureable as a high-side current source output for indicator LED or comparator input for LED temperature sensing |
C2 | TX1/TORCH/GPIO1 | Input/Output | Configureable as a dual-polarity RF power amplifier synchronization input, a hardware torch mode enable, or as a general purpose logic I/O. This pin has an internal 300-kΩ pulldown to GND. |
C3 | STROBE | Input | Active high hardware flash enable. Drive STROBE high to turn on the flash current pulse. This pin has an internal 300-kΩ pulldown to GND. |
C4 | IN | Power | Input voltage connection. Connect IN to the input supply, and bypass to GND with a minimum 10-µF or larger ceramic capacitor. |
D1 | TX2/INT/GPIO2 | Input/Output | Configurable as a dual-polarity power amplifier synchronization input, an interrupt output, or as a general purpose logic I/O. This pin has an internal 300-kΩ pulldown to GND. |
D2 | SDA | Input/Output | Serial data input output. High impedance in shutdown or in power down. |
D3 | SCL | Input | Serial clock input. High impedance in shutdown or in power down. |
D4 | HWEN | Input | Logic high hardware enable. HWEN is a high impedance input and is normally connected with an external pullup resistor to a logic high voltage. |
MIN | MAX | UNIT | ||
---|---|---|---|---|
VIN | –0.3 | 6 | V | |
VSCL, VSDA, VHWEN, VSTROBE, VTX1, VTX2, VLED1, VLED2, VLEDI/NTC | –0.3 | to the lesser of (VIN + 0.3 V) with 6 V maximum | V | |
VSW, VOUT | –0.3 | 6 | V | |
Continuous power dissipation(2) | Internally limited | |||
Junction temperature, TJ-MAX | 150 | °C | ||
Storage temperature, Tstg | –65 | 150 | °C |
VALUE | UNIT | |||
---|---|---|---|---|
V(ESD) | Electrostatic discharge | Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001(1) | ±2000 | V |
MIN | MAX | UNIT | ||
---|---|---|---|---|
Input voltage, VIN | 2.5 | 5.5 | V | |
Junction temperature, TJ | –40 | 125 | °C | |
Ambient temperature, TA(1) | –40 | 85 | °C |
THERMAL METRIC(1) | LM3559 | UNIT | |
---|---|---|---|
YZR (DSBGA) | |||
16 PINS | |||
RθJA | Junction-to-ambient thermal resistance(2) | 71.3 | °C/W |
RθJC(top) | Junction-to-case (top) thermal resistance | 18.4 | °C/W |
RθJB | Junction-to-board thermal resistance | 9.8 | °C/W |
ψJT | Junction-to-top characterization parameter | 1.7 | °C/W |
ψJB | Junction-to-board characterization parameter | 1.7 | °C/W |
RθJC(bot) | Junction-to-case (bottom) thermal resistance | 9.7 | °C/W |
PARAMETER | TEST CONDITIONS | MIN | TYP | MAX | UNIT | |||
---|---|---|---|---|---|---|---|---|
CURRENT SOURCE SPECIFICATIONS | ||||||||
ILED | Current source accuracy | ILED1 + ILED2, 3 V ≤ VIN ≤ 4.2 V, VOUT = 4.5 V | 900-mA flash current setting, per current source | –7% | 1800 | 7% | mA | |
900-mA flash current setting, per current source –40°C ≤ TA ≤ 85°C |
–4% | 1800 | 4% | |||||
28.125-mA torch current, per current source | –10% | 56.2 | 10% | |||||
28.125-mA torch current, per current source –40°C ≤ TA ≤ 85°C |
||||||||
VOUT – VLED1/2 | Current source regulation voltage | ILED = 1.8 A (ILED1 + ILED2), VOUT = 4.5 V | 270 | mV | ||||
VOVP | Output overvoltage protection trip point(3) | ON threshold | 5 | V | ||||
ON threshold, –40°C ≤ TA ≤ 85°C | 4.925 | 5.075 | ||||||
OFF threshold | 4.88 | |||||||
STEP-UP DC-DC CONVERTER SPECIFICATIONS | ||||||||
RPMOS | PMOS switch on-resistance | IPMOS = 1A | 80 | mΩ | ||||
RNMOS | NMOS switch on-resistance | INMOS = 1A | 80 | mΩ | ||||
ICL | Switch current limit(4) | 3 V ≤ VIN ≤ 4.2 V | Flash Duration Register bits [6:5] = 00 | 1.4 | A | |||
3 V ≤ VIN ≤ 4.2 V –40°C ≤ TA ≤ 85°C |
1.2 | 1.6 | ||||||
3 V ≤ VIN ≤ 4.2 V | Flash Duration Register bits [6:5] = 01 | 2.1 | ||||||
3 V ≤ VIN ≤ 4.2 V –40°C ≤ TA ≤ 85°C |
1.8 | 2.3 | ||||||
3 V ≤ VIN ≤ 4.2 V | Flash Duration Register bits [6:5] = 10 | 2.7 | ||||||
3 V ≤ VIN ≤ 4.2 V –40°C ≤ TA ≤ 85°C |
2.4 | 3 | ||||||
3 V ≤ VIN ≤ 4.2 V | Flash Duration Register bits [6:5] = 11 | 3.2 | ||||||
3 V ≤ VIN ≤ 4.2 V –40°C ≤ TA ≤ 85°C |
2.9 | 3.5 | ||||||
IOUT_SC | Output short-circuit current limit | VOUT < 2.3 V | 350 | mA | ||||
ILEDI/NTC | Indicator current | Register 0x12, bits[2:0] = 111, 2.7 V ≤ VIN ≤ 4.2 V VLEDI/NTC = 2 V, –40°C ≤ TA ≤ 85°C |
18 | mA | ||||
Register 0x12, bits[2:0] = 111, 2.7 V ≤ VIN ≤ 4.2 V VLEDI/NTC = 2 V |
16 | 20 | ||||||
VTRIP | Comparator trip threshold | Configuration register 1, bit [4] = 1, 3 V ≤ VIN ≤ 4.2 V |
1 | V | ||||
Configuration register 1, bit [4] = 1, 3 V ≤ VIN ≤ 4.2 V, –40°C ≤ TA ≤ 85°C |
0.97 | 1.03 | ||||||
ƒSW | Switching frequency | 2.7 V ≤ VIN ≤ 5.5 V | 2 | MHz | ||||
2.7 V ≤ VIN ≤ 5.5 V, –40°C ≤ TA ≤ 85°C | 1.8 | 2.2 | ||||||
IQ | Quiescent supply current | Device not switching, VOUT = 3V | 650 | µA | ||||
Device switching, VOUT = 4.5V | 1.55 | mA | ||||||
Indicate mode, Indicator Register bits [2:0] = 111 VLEDI/NTC = 2 V |
590 | µA | ||||||
Indicate mode, Indicator Register bits [2:0] = 111 VLEDI/NTC = 2 V, –40°C ≤ TA ≤ 85°C |
750 | |||||||
ISHDN | Shutdown supply current | 2.7 V ≤ VIN ≤ 5.5 V, –40°C ≤ TA ≤ 85°C | HWEN = GND | 1 | µA | |||
ISTBY | Standby supply current | 2.7 V ≤ VIN ≤ 5.5 V | HWEN = VIN, Enable Register bits [1:0] = 00 | 1.25 | µA | |||
2.7 V ≤ VIN ≤ 5.5 V, –40°C ≤ TA ≤ 85°C | 2.4 | |||||||
VIN_TH | VIN monitor threshold | VIN Monitor Register = 0x01 | 2.9 | V | ||||
VIN Monitor Register = 0x01, –40°C ≤ TA ≤ 85°C | 2.85 | 2.95 | ||||||
VIN_FLASH_TH | VIN flash monitor threshold | VIN Monitor Register = 0x08 | 2.9 | V | ||||
VIN Monitor Register = 0x08, –40°C ≤ TA ≤ 85°C | 2.85 | 2.95 | ||||||
tTX | Flash-to-torch LED current settling time | TX_ Low to High ILED1 + ILED2 = 1.8A to 112.5mA |
20 | µs | ||||
tD | Time from when ILED hits target until VLED data is available | ADC Delay Register bit [5] = 1 | 16 | µs | ||||
ADC Delay Register bit [5] = 0 ADC Delay Register bits [4:0] = 0000 |
250 | |||||||
VF_ADC | ADC threshold | VLED Monitor Register bits [3:0] = 1111 | 4.6 | V | ||||
VLED Monitor Register bits [3:0] = 1111 –40°C ≤ TA ≤ 85°C |
4.4 | 4.8 | ||||||
HWEN, STROBE, TX1/TORCH/GPIO1, TX2/INT/GPIO2 VOLTAGE SPECIFICATIONS | ||||||||
VIL | Input logic low | 2.7 V ≤ VIN ≤ 5.5 V, –40°C ≤ TA ≤ 85°C | 0 | 0.4 | V | |||
VIH | Input logic high | 2.7 V ≤ VIN ≤ 5.5 V, –40°C ≤ TA ≤ 85°C | 1.2 | VIN | V | |||
RPD | Internal pulldown resistance on TX1, TX2, STROBE | 300 | kΩ | |||||
I2C-COMPATIBLE VOLTAGE SPECIFICATIONS (SCL, SDA) | ||||||||
VIL | Input logic low | 2.7 V ≤ VIN ≤ 5.5 V, –40°C ≤ TA ≤ 85°C | 0 | 0.4 | V | |||
VIH | Input logic high | 2.7 V ≤ VIN ≤ 5.5 V | 1.3 | VIN | V | |||
VOL | Output logic low (SDA) | ILOAD = 3 mA 2.7 V ≤ VIN ≤ 5.5 V, –40°C ≤ TA ≤ 85°C |
0.4 | V |
MIN | NOM | MAX | UNIT | ||
---|---|---|---|---|---|
1/t1 | SCL(clock frequency) | 400 | kHz | ||
t2 | Data in setup time to SCL high | 100 | ns | ||
t3 | Data out stable after SCL low | 0 | ns | ||
t4 | SDA low setup time to SCL low (start) | 100 | ns | ||
t5 | SDA high hold time after SCL high (stop) | 100 | ns |
Enable Register = 0x18 |
Register Bits [2:0] = 0x02 |
Upper 5 Flash Brightness Codes |
Upper 4 Torch Brightness Codes |
VHWEN= 0 V |
Register Bits [2:0] = 0x00 |
Register Bits [2:0] = 0x07 |
Middle 5 Flash Brightness Codes |
Lower 4 Torch Brightness Codes |
TX2 Active High |