a8434 Allegro MicroSystems, Inc., a8434 Datasheet - Page 4

• Manufacturer Part Number: a8434
• Description: 6-channel High Efficiency Charge Pump White Led Driver
• Manufacturer: Allegro MicroSystems, Inc.

A8434
ELECTRICAL CHARACTERISTICS
T
Input Voltage Range
Undervoltage Lockout Threshold
UVLO Hysteresis Window
Quiescent Current
Soft-start Completion Time
ISET Bias Voltage
ISET Leakage in Shutdown
ISET Current Range
ISET to LEDx Current Ratio for LED1 through LED6
I
LED Current Matching for LED1 through LED4
LED Current Matching for LED5 and LED6
Regulation Voltage at LEDx (1.5× and 2× modes)
1× mode to 1.5× or 1.5× to 2× mode transition voltage at LEDx
Transition–Dropout Delta
Open Loop Output Resistance
LED Leakage in Shutdown
Oscillator Frequency
Output Overvoltage Protection (guaranteed by design)
ENS and ENM Input High Threshold
ENS and ENM Input Low Threshold
Input High Current
Input Low Current
ENM and ENS Pulse Low Time (figure 5)
ENM and ENS Pulse High Time (figure 5)
ENM and ENS Initial Pulse High Time (figure 5)
Shutdown or Dimming Reset Delay
Thermal Shutdown Threshold
a
b
c
d
e
voltage is always less than 80 mV).
LED
LED current matching is defined as (I
Specifications for the range T
I
Dropout voltage V
The open loop output resistance, R
A
LED
= –40°C to +85°C; typical values are at T
Accuracy for LED1 through LED6
accuracy is defined as ( I
dropout
Characteristics
d
is defined as LEDx-to-GND voltage at which I
e
A
SET
= –40°C to 85°C are guaranteed by design.
b
× 220 – I
OUT
a
c
VIN = ENM = ENS = 3.6 V, C1 = C2 = 1 μF, CIN = COUT = 1 μF, RSET = 6.49 kΩ,
LEDx
, for 1.5 × mode is measured when one of the LEDx pins is tied to ground or open (thus its
c
LEDAVG
– I
A
= 25°C; unless otherwise noted
LEDAVG
) / (I
6-Channel High Efficiency Charge Pump
SET
) / I
LEDAVG
× 220).
I
V
V
E
V
LEDx
Symbol
V
ΔI
ΔI
UVLOHYS
V
ISETBIAS
ILEDERR
ISETLKG
V
t
V
R
LEDLKG
ΔV
t
T
V
SHDN
I
.
V
f
V
INIHI
UVLO
LED14
LED56
V
t
t
SET
REG
trans
I
t
I
OUT
osc
I
LO
TSD
ovp
ss
IH
HI
Q
IL
IN
/I
IH
IL
dr
ISET
V
Switching in 1.5× or 2.0× mode; T
ENS = ENM = GND; T
100% setting, I
ENS = ENM = VIN
ENS = GND, ENM = VIN
ENS = VIN, ENM = GND
ENS = ENM = VIN
V
Measured as V
1× mode (V
1.5× mode (1.5 × V
2× mode (2 × V
ENS = ENM = GND, V
Open circuit at any LED that is programmed
to be in the ON state
Input high logic threshold
Input low logic threshold
V
V
First ENM or ENS pulse after shutdown
Falling edge of ENS and/or ENM
20
LEDx
IN
LEDx
IH
IL
o
= GND
=VIN
C hysteresis
falling
drops 10% below the value of I
falling
IN
Test Conditions
– V
SET
trans
IN
OUT
– V
= 60 μA
IN
– V
A
) / I
OUT
IN
– V
= 25°C
dropout
= 5.5 V
OUT
) / I
OUT
OUT
) / I
115 Northeast Cutoff, Box 15036
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 [phone]
www.allegromicro.com
OUT
White LED Driver
A
= 25°C
LEDx
when V
Min.
2.25
2.7
1.4
0.5
0.5
40
50
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
Typ. Max. Units
2.45
0.01
±1.6
±0.5
±0.5
0.01
220
250
150
165
0.1
0.4
0.6
0.5
LEDx
2.5
60
40
–
6
–
1
5
1
–
–
–
–
–
–
–
–
= 300 mV.
2.60
140
250
5.5
6.0
0.4
2
–
1
–
–
–
1
1
1
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
MHz
A/A
mV
mA
mV
mV
mV
ms
ms
μA
μA
μA
μA
μA
μA
μs
μs
μs
o
%
%
%
V
V
V
Ω
Ω
Ω
V
V
V
C
4