Ultra-Efficient Charge Pumps for
Six White/RGB LEDs in 3mm x 3mm Thin QFN
ELECTRICAL CHARACTERISTICS (continued)
(V
= V = 3.6V, V
= 0V, T = -40°C to +85°C, unless otherwise noted. Typical values are at T = +25°C.) (Note 1)
GND A A
VDD
IN
PARAMETER
CONDITIONS
MIN
TYP
+60
-2.5
3
MAX
UNITS
°C
Derating-Function Start Temperature
Derating-Function Slope
From derating-function start temperature
Not utilizing the charge pump
Utilizing the charge pump
%/°C
LED_ R
Ω
DSON
4
Not utilizing the charge pump
Utilizing the charge pump
60
120
200
24mA setting
(Note 3)
LED_ Dropout
mV
mV
mV
µA
90
LED_ Current Regulator Switchover
Threshold (Inactive to Active)
V
falling
125
150
100
175
LED_
LED_ Current Regulator Switchover
Hysteresis
T
T
= +25°C
= +85°C
0.01
0.1
5
A
LED_ Leakage in Shutdown
All LEDs off
A
7/MAX648
Note 1: Limits are 100% production tested at T = +25°C. Specifications over the operating temperature range are guaranteed by design.
A
Note 2: Guaranteed by design.
Note 3: LED dropout voltage is defined as the LED_ to GND voltage at which current into LED_ drops 10% from the value at V
= 0.5V.
LED_
Typical Operating Characteristics
(V = 3.6V, V
IN
= V , circuit of Figure 1, T = +25°C, unless otherwise noted.)
IN A
EN_
EFFICIENCY vs. SUPPLY VOLTAGE
(DRIVING SIX MATCHED LEDs)
EFFICIENCY vs. Li+ BATTERY VOLTAGE
EFFICIENCY vs. SUPPLY VOLTAGE
(DRIVING SIX LEDs)
(DRIVING SIX MATCHED LEDs)
100
90
80
70
60
50
40
30
20
10
0
100
90
80
70
60
50
40
30
20
10
0
100
90
80
70
60
50
40
20.8mA/LED
16mA/LED
1.6mA/LED
20.8mA/LED
1.6mA/LED
16mA/LED
1.6mA/LED
6.4mA/LED
16mA/LED
6.4mA/LED
LEDs HAVE MISMATCHED V
F
2.7
3.0
3.3
3.6
3.9
4.2
2.7
3.0
3.3
3.6
3.9
4.2
4.2 3.9
3.8
3.7
3.6
3.5 3.4 3.0
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
Li+ BATTERY VOLTAGE (V, TIME-WEIGHTED)
4
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MAXIM [ MAXIM INTEGRATED PRODUCTS ]
