MAX1583YETB+T Maxim Integrated Products, MAX1583YETB+T Datasheet - Page 8

• Manufacturer Part Number: MAX1583YETB+T
• Description: IC LED DRIVR PHOTO FLASH 10-TDFN
• Manufacturer: Maxim Integrated Products
• Type: Photo Flash LEDr

Specifications of MAX1583YETB+T

• Constant Current: Yes
• Topology: Step-Up (Boost)
• Number Of Outputs: 1
• Internal Driver: Yes
• Type - Primary: Flash/Torch
• Type - Secondary: White LED
• Frequency: 750kHz ~ 1.25MHz
• Voltage - Supply: 2.6 V ~ 5.5 V
• Voltage - Output: 24V
• Mounting Type: Surface Mount
• Package / Case: 10-TDFN Exposed Pad
• Operating Temperature: -40°C ~ 85°C
• Current - Output / Channel: 500mA
• Internal Switch(s): Yes
• Efficiency: 80%
• Number Of Segments: 5
• Operating Supply Voltage: 2.6 V to 5.5 V
• Maximum Power Dissipation: 1951 mW
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The LED current in the strobe and movie modes is pro-
grammable using external resistors. To set the LED cur-
rent during strobe mode, connect a resistor (R
STB to GND. V
sourced by STB is mirrored through LED with a gain of
1000. R
To set the LED current during movie mode, connect a
resistor (R
to 0.6V and the current sourced by MOV is mirrored
through LED with a gain of 100. R
During strobe mode, the current demands on the boost
converter to maintain the desired LED strobe current
may cause the MAX1583 to reach the preset current
limit. The MAX1583 is available with three factory-pre-
set current limits: 250mA, 500mA, and 1A. If the current
limit is reached, the internal MOSFET terminates its ON
cycle early, causing the output current to drop. See the
Typical Operating Characteristics for the Maximum
Boost I
strobe current exceeds the maximum boost I
White LED Camera-Flash
Boost Converter
Figure 1. Typical Application Circuit
8
Reservoir Capacitance vs. Current Limit
_______________________________________________________________________________________
OUT
STB
MOV
vs. V
is calculated as:
R
R
) from MOV to GND. V
STB
STB
MOV
IN
for each current limit. If the required
is regulated to 0.6V and the current
= 600 / I
= 60 / I
Adjusting the LED Current
POWER-OK
Design Procedure
LED(DESIRED)
LED(DESIRED)
MODE CONTROL
2.6V TO 5.5V
100kΩ
V
MOV
R3
IN
MOV
is calculated as:
22μF
C1
6.04kΩ
3.01kΩ
1%
1%
R1
R2
is regulated
OUT
STB
2
1
5
6
7
4
3
IN
GND
POK
EN1
EN2
STB
MOV
) from
, con-
MAX1583X
4.7μH
L1
nect a reservoir capacitor from OUT to GND to provide
the extra LED current. The value of this capacitor is cal-
culated as:
where:
I
I
er obtained from the Typical Operating Characteristics,
t
n is the number of LEDs, and
V
For example, assume a minimum input voltage of 3.2V
with the MAX1583Y (500mA current limit). The required
strobe current is 100mA for 30ms through two series
LEDs with a 4V forward voltage. The reservoir capacitor
is determined as follows:
I
Characteristics.
C
LED
BOOST
STROBE
BOOST
F
OUT
LED
RES
LX
is the forward voltage of the LEDs.
is the desired strobe current,
10
8
9
=
is the maximum current from the boost convert-
10μF
(
is the time duration of the strobe,
100
D1
C2
= 75mA from the Typical Operating
C
RES
mA
24
0.1μF
C3
V
−
=
75
−
(
I
(
LED
2 4
mA
×
)
−
×
V
24
I
BOOST
)
30
V
ms
D2, D3, D4
WHITE LEDs
−
(
n V
=
)
×
×
25
t
F
STROBE
mA
)
16
×
V
30
ms
=
47
μ
F