Datasheet

LT3745-1
5
37451f
TIMING CHARACTERISTICS
The l denotes the specifications which apply over the full operating temperature
range, otherwise specifications are at T
A
= 25°C. V
IN
= 12V, V
CC
= 3V to 3.6V, V
EN/UVLO
= 1.5V, V
FB
= 1.5V, V
ISP
= V
ISN
= 5V,
V
LEDxx
= 1V, R
T
= 105k, R
ISET
= 60.4k, C
CAP
= 0.47µF to V
IN
, C
SCKO
+
/SCKO
– = C
SDO
+
/SDO
– = 15pF, unless otherwise noted.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
f
SCKI
Data Shift Clock Frequency
l
30 MHz
f
PWMCK
PWMCK Clock Frequency
l
25 MHz
t
WH-CKI
t
WL-CKI
SCKI Pulse Duration SCKI = H (Figure 3)
SCKI = L (Figure 3)
l
l
16
16
ns
ns
t
WH-PWM
t
WL-PWM
PWMCK Pulse Duration PWMCK = H (Figure 4)
PWMCK = L (Figure 4)
l
l
20
20
ns
ns
t
WH-LDI
LDI Pulse Duration LDI = H (Figure 3)
l
20 ns
t
SU-SDI
SDI-SCKI Setup Time
SDI – SCKI
(Figure 3)
l
5 ns
t
HD-SDI
SCKI-SDI Hold Time
SCKI – SDI (Figure 3)
l
5 ns
t
SU-LDI
SCKI-LDI Setup Time
SCKI – LDI (Figure 3)
l
5 ns
t
HD-LDI
LDI-SCKI Hold Time
LDI – SCKI (Figure 3)
l
15 ns
t
PD-SCK
SCKI-SCKO Propagation Delay (Rising)
SCKI – SCKO (Figure 3)
l
33 50 ns
t
PD-SCK
SCKI-SCKO Propagation Delay (Falling)
SCKI – SCKO (Figure 3)
l
33 50 ns
t
PD-SCK
SCK Duty Cycle Change
t
PD-SCK
= t
PD-SCK
– t
PD-SCK
0 ns
t
PD-SD
SCKO-SDO Propagation Delay
SCKO – SDO (Figure 3)
l
2 5 8 ns
t
PD-PWM
PWMCK-LED Propagation Delay
PWMCK – I
LED
(Figure 4)
55 ns
t
R-SO
SCKO/SDO Rise Time C
LOAD
= 15pF, 10% to 90% 2.6 ns
t
F-SO
SCKO/SDO Fall Time C
LOAD
= 15pF, 90% to 10% 2.6 ns
Table 1. Test Parameter Equations
I
LEDC
(%) =
I
OUTmax(015)
I
OUTmin(015)
2I
OUTavg(015)
100
(1)
I
LEDD
(%) =
I
OUTavg(015)
I
OUTcal
I
OUTcal
100
(2)
I
OUTcal
= 2500
1.205V
R
ISET
(3)
I
LINE
(% / V) =
I
OUTn
V
CC
= 3.6V – I
OUTn
V
CC
= 3V
I
OUTn
V
CC
= 3V
100
0.6V
(4)
I
LOAD
(% / V) =
I
OUTn
V
OUTn
= 3V I
OUTn
V
OUTn
= 1V
I
OUTn
V
OUTn
= 1V
100
2V
(5)
V
ID
= V(DI
+
) V(DI
)
(6)
V
CM
=
V(DI
+
)+ V(DI
)
2
(7)
V
OD
= V(DO
+
) V(DO
)
(8)
V
OS
=
V(DO
+
)+ V(DO
)
2
(9)