Electrical characteristics (continued) – Rainbow Electronics MAX8848Z User Manual
Page 3
High-Performance Negative Charge Pump
for 7 White LEDs in 3mm x 3mm Thin QFN
MAX8848Y/MAX8848Z
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= 3.6V, V
GND
= 0V, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 2)
Note 2: Limits are 100% production tested at T
A
= +25°C. Limits over the operating temperature range are guaranteed by design.
Note 3: Guaranteed by design. Not production tested.
Note 4: LED dropout voltage is defined as the LED_ to GND voltage at which current into LED_ drops 10% from the value at
V
LED_
= 0.5V.
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
EN_ Low Shutdown Delay
t
SHDN
5
8
ms
EN_ t
LO
See Figure 2
1
500
F
s
EN_ t
HI
See Figure 2
1
F
s
Initial EN_ t
INIT
See Figure 2, first EN_ high pulse
120
F
s
CHARGE PUMP
Switching Frequency
1
MHz
Soft-Start Time
0.5
ms
Output Regulation Voltage
V
IN
- V
NEG
4.3
5
V
Open-Loop NEG Output
Resistance
(V
NEG
- 0.5 x V
IN
)/I
NEG
2
4
I
NEG Shutdown Discharge
Resistance
V
EN
_ = 0V, all outputs off
10
kI
LED1–LED7 CURRENT REGULATOR
Current Setting Range
Serial-pulse interface or PWM
0.1
24.0
mA
LED_ Current Accuracy
V
LED_
= 0.5V for charge
pump inactive,
V
LED_
= -0.9V,
V
NEG_
= -1.4V
24mA setting, T
A
= +25NC
-2
Q
1
+2
%
24mA setting, T
A
= -40NC
to derating function start
temperature (Note 3)
-5
+5
1.6mA setting, T
A
= +25NC
Q
5
Derating Function Start
Temperature
+60
N
C
Derating Function Slope
From derating function start temperature
-2.5
%/NC
LED_ Dropout Voltage
(Note 4)
Charge pump inactive,
24mA setting
T
A
= +25NC
85
125
mV
T
A
= +85NC
95
Charge pump active,
24mA setting
T
A
= +25NC
110
T
A
= +85NC
124
LED_ Current Regulator
Switchover Threshold
(Inactive to Active)
V
LED_
falling
135
150
165
mV
LED_ Current Regulator
Switchover Hysteresis
100
mV
LED_ Leakage in Shutdown
All LEDs off
T
A
= +25NC
0.01
5
F
A
T
A
= +85NC
0.1