LM2753SD/NOPB National Semiconductor, LM2753SD/NOPB Datasheet - Page 9

• Manufacturer Part Number: LM2753SD/NOPB
• Description: IC LED DRIVER PHOTO FLASH 10-LLP
• Manufacturer: National Semiconductor
• Type: Photo Flash LEDr

Specifications of LM2753SD/NOPB

• Topology: PWM, Switched Capacitor (Charge Pump)
• Number Of Outputs: 1
• Internal Driver: Yes
• Type - Primary: Flash/Torch
• Type - Secondary: White LED
• Frequency: 725kHz
• Voltage - Supply: 3 V ~ 5.5 V
• Voltage - Output: 5V
• Mounting Type: Surface Mount
• Package / Case: 10-LLP
• Operating Temperature: -40°C ~ 85°C
• Current - Output / Channel: 250mA
• Internal Switch(s): Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Efficiency: -
• Other names: LM2753SD; LM2753SDTR

the LM2753 has a switch array with multiple switches con-
nected in parallel.
The number of switches used in parallel depends on the input
voltage applied to the LM2753. At lower input voltages all
paralleled switches are used, and as the input voltage rises,
switches are removed from the parallel configuration. The
highest switch resistance is achieved as the input voltage
reaches the maximum operating voltage, which helps with
voltage management.
THERMAL PROTECTION
When the junction temperature exceeds 140°C (typ.), the
LM2753 internal thermal protection circuitry disables the part.
This feature protects the device from damage due to exces-
sive power dissipation. The device will recover and operate
normally when the junction temperature falls below 125°C
(typ.). It is important to have good thermal conduction with a
proper layout to reduce thermal resistance.
POWER EFFICIENCY
Charge-Pump efficiency is derived in the following two ideal
equations (supply current and other losses are neglected for
simplicity):
In the equations, G represents the charge pump gain. Effi-
ciency is at its highest as G x V
E = (V
OUT
x I
OUT
) ÷ (V
I
IN
= G x I
IN
x I
IN
IN
OUT
approaches V
) = V
OUT
÷ (G x V
OUT
. Refer to
IN
)
9
the efficiency graph in the Typical Performance Character-
istics section for the detailed efficiency data.
POWER DISSIPATION
The power dissipation (P
(T
product of the input current and input voltage, P
power consumed by the load connected to the output, T
the ambient temperature, and θ
thermal resistance for the LLP-10 package. V
voltage to the LM2753, V
the device, and I
connected to both V
The junction temperature rating takes precedence over the
ambient temperature rating. The LM2753 may be operated
outside the ambient temperature rating, so long as the junc-
tion temperature of the device does not exceed the maximum
operating rating of 120°C. The maximum ambient tempera-
ture rating must be derated in applications where high power
dissipation and/or poor thermal resistance causes the junc-
tion temperature to exceed 120°C.
J
) can be approximated with the equations below. P
T
= (V
OUT
J
P
= T
DISSIPATION
OUT
is the total current supplied to the load(s)
IN
A
× I
+ (P
DISSIPATION
and I
IN
VOUT
) − (V
DISSIPATION
OUT
= P
is the voltage at the output of
JA
VOUT
.
IN
) and junction temperature
is the junction-to-ambient
- P
× I
× θ
OUT
OUT
JA
)
)
IN
www.national.com
is the input
OUT
IN
is the
is the
A
is