LM3561 datasheet(4/37 Pages) TI1

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LM3561

SNOSB44C – MARCH 2011 – REVISED MAY 2013

www.ti.com

Thermal Properties

Junction-to-Ambient Thermal Resistance (

θJA)

(1)

68°C/W

(1)

Junction-to-ambient thermal resistance (

θJA) is taken from a thermal modeling result, performed under the conditions and guidelines set

forth in the JEDEC standard JESD51-7. The test board is a 4-layer FR-4 board measuring 102mm x 76mm x 1.6mm with a 2x1 array of

thermal via's. The ground plane on the board is 50mm x 50mm. Thickness of copper layers are 36µm/18µm/18µm/36µm

(1.5oz/1oz/1oz/1.5oz). Ambient temperature in simulation is 22°C, still air. Power dissipation is 1W.

Electrical Characteristics

Limits in standard typeface are for TA = +25°C. Limits in boldface type apply over the full operating ambient temperature

range (-40°C

≤ TA ≤ +85ºC). Unless otherwise specified, VIN = 3.6V, VHWEN = VIN.

(1) (2)

Parameter

Test Conditions

Min

Typ

Max

Unit

Current Source Specifications

600mA Flash LED

-40C

≤ TA ≤ +85C

-5%

600

+6%

Setting, VOUT =

4.5V, 3V

≤ VIN ≤

TA = +25C

-3%

600

+6%

ILED

Current source accuracy

4.2V

18mA Torch Current Setting,

-10%

+10%

VOUT = 4.5V, 3V ≤ VIN ≤ 4.2V

Current Source Regulation

VHR

600mA setting, VOUT = 4.5V

240

Voltage (VOUT - VLED)

Step-Up DC/DC Converter Specifications

On Threshold

4.90

5.05

Output over-voltage protection

VOVP

trip point(3)

Off Threshold

4.88

RPMOS

PMOS switch on-resistance

IPMOS = 500mA

270

Ω

RNMOS

NMOS switch on-resistance

INMOS = 500mA

250

Ω

Flash Duration

0.88

1.12

ICL

Switch current limit(4)

3.0V

≤ VIN ≤ 4.2V

Flash Duration

1.35

1.5

1.65

IOUT_SC

Output short circuit current limit

VOUT < 2.3V

200

Indicator Register = 0xFF,

ILED/NTC

Indicator current

VLEDI/NTC = 2V, 2.7V ≤ VIN ≤ 4.2V

Configuration Register 1 Bit [4] = 1,

VTRIP

Comparator trip threshold

0.97

1.03

3.0V

≤ VIN ≤ 4.2V

fSW

Switching frequency

2.7V

≤ VIN ≤ 5.5V

1.8

2.2

MHz

tTIMEOUT

Timeout duration(5), (6)

2.7V

≤ VIN ≤ 5.5V

-10

+10

Device Not Switching

676

Quiescent supply current into

Device Switching

1140

µA

Indicate Mode,

560

Indicator Register = 0x07

ISHDN

Shutdown supply current

2.7V

≤ VIN ≤ 5.5V, HWEN = GND

0.02

µA

(1)

All voltages are with respect to the potential at the GND pin.

(2)

Min and Max limits are specified by design, test, or statistical analysis. Typical (Typ) numbers are not ensured, but do represent the

most likely norm. Unless otherwise specified, conditions for typical specifications are: VIN = 3.6V and TA = +25°C.

(3)

The typical curve for Over-Voltage Protection (OVP) is measured in closed loop using the typical application circuit. The OVP value is

found by forcing an open circuit in the LED current path and recording the peak value of VOUT. The value given in the Electrical Table is

found in an open loop configuration by ramping the voltage at OUT until the OVP comparator trips. The closed loop data can appear

higher due to the stored energy in the inductor being dumped into the output capacitor after the OVP comparator trips. This results in an

open circuit condition where the output voltage can continue to rise after the OVP comparator trips by approximately IIN × sqrt(L/COUT).

(4)

The typical curve for Current Limit is measured in closed loop using the typical application circuit by increasing IOUT until the peak

inductor current stops increasing. The value given in the Electrical Table is measured open loop and is found by forcing current into SW

until the current limit comparator threshold is reached. Closed loop data appears higher due to the delay between the comparator trip

point and the NFET turning off. This delay allows the closed loop inductor current to ramp higher after the trip point by approximately

40ns × VIN/L

(5)

Specified by design. Not production tested.

(6)

The timeout duration period is a divided down representation of the 2MHz clock and thus the accuracy spec. is the same as the

switching frequency. This accuracy specification applies to all settings in Table 10.

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