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부품번호 | AT9932 기능 |
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기능 | Automotive Boost-Buck LED Lamp Driver IC | ||
제조업체 | Supertex | ||
로고 | |||
전체 10 페이지수
Supertex inc.
AT9932www.DataSheet4U.com
Automotive Boost-Buck
LED Lamp Driver IC
Features
► Constant output current
► Steps output voltage up or down
► Very low susceptibility to Input voltage transients
► Frequency jitter
► Externally programmable fixed switching frequency
► Temperature foldback with external NTC resistor
► Internal 40V voltage regulator
► +/-1A MOSFET gate driver
► Short LED protection
► Open LED protection
► Input undervoltage protection
► Enable & PWM dimming
► Trimmed reference (±3% accurate)
► AEC-Q100 compliant
Applications
► Automobile lighting
► Battery powered LED lamps
► Other low voltage AC/DC or DC/DC LED drivers
General Description
The AT9932 is an advanced fixed frequency PWM
controller IC designed to control an LED lamp driver using
a boost-buck topology that can step the input voltage up
or down automatically. The IC provides fast output current
transient response and very low susceptibility to input
voltage transients, which allows the lamp driver to pass the
rigorous electrical transient requirements of SAE J1455 or
ISO 7637-2, making the AT9932 an ultimate solution for
automobile lighting. Capacitive isolation protects the LED
Lamp from failure of the switching MOSFET.
The AT9932 features a unique feed-forward current control
scheme, differential output current sensing, soft start,
protection from short or open LED load. Switching frequency
can be programmed with a single external resistor.
The AT9932 includes a temperature fold-back of the output
current using an external NTC resistor. This feature allows
maximizing the light output of the LED load over the entire
operating temperature range.
Typical Application Circuit
CIN L1 Rd C1 Cd
RIN
CVDD
VIN
AVDD
PVDD
PWMD
GATE
FFP
FFN
UVLO
RT
RINC
RT
REF
FLT
CSS SS
PGND
RNTC
GND
NTC
FB
DRP
COMP
T1
R2 R1
DIV
T2
JTR
AT9932
M1
RP
RN
RREF
RFLT
RDRP
CC
R3
CJTR
D1
CREF
L2 CO
ZD1 LED(s)
RFB
ROV
RS
Supertex inc. ● 1235 Bordeaux Drive, Sunnyvale, CA 94089 ● Tel: 408-222-8888 ● www.supertex.com
AT9932
www.DataSheet4U.com
Electrical CharacteristicsCREF
=
0.1µF,
CAVDD
=
CPVDD
=
1.0µF,
IT1
=
IT2
=
(Specifications are
100µA unless otherwise
antoTteAd=.)25OC,
VIN
=
12V,
VPWMD
=
UVLO
=
AVDD
=
PVDD,
GATE
open,
RT
=
200KΩ,
Sym Description
Min Typ Max Units Conditions
Jitter
FJTR Jitter frequency
- - 50 - Hz CJTR = 0.1µF
- - 500 - Hz CJTR = 0.01µF
ΔF Change in switching frequency - ±4.5
-
- kHz ---
Temperature Foldback Circuit
INTC
NNTC
NT1
NT2
VT1, VT2
Soft Start
NTC current range
NTC to DRP current gain
NTC to T1 current gain
NTC to T2 current gain
T1 and T2 reference voltage
ISS,CHG Charging current
ISS,DIS
Discharging current
VSS,RST Reset voltage
Fault Detect Comparator
VFLT Trip voltage
IBIAS Input bias current
Input Under Voltage Lockout
∆VUVLO
Under voltage threshold
hysteresis
VUVLO,ON
IBIAS
Under voltage threshold
Input bias current
PWM Dimming
Enable voltage level
VEN, VPWM Disable voltage level
#-
--
--
--
--
- 10
- 1.0
--
- -20
#-
--
* 1.15
#-
* 2.0
*-
-
0.13
3.0
6.0
3.5
-
-
-
-
0.5
200
1.25
0.5
-
-
1.0
-
-
-
-
25
-
100
20
1.0
-
1.40
1.0
-
0.8
mA ---
- INTC = 0.5mA
- INTC = 0.5mA
- INTC = 0.5mA
V ---
µA ---
mA VSS = 5.0V
mV ---
mV ---
nA ---
mV UVLO falling
V UVLO rising
nA ---
V ---
V ---
RPWMD Pull-down resistor
- 120 - 280 kΩ ---
Notes:
*
#
Specifications
Specifications
apply over the full operating ambient temperature range
guaranteed by design and not tested in production
of
-40ºC
<
TA
<
+125ºC.
Guaranteed
by
design
and
characterization.
Supertex inc. ● 1235 Bordeaux Drive, Sunnyvale, CA 94089 ● Tel: 408-222-8888 ● www.supertex.com
4
4페이지 AT9932
www.DataSheet4U.com
where VIN is the input supply voltage, and VOUT is the forward
voltage of the LED string. Since the output voltage at COMP
is limited to VCOMP = VDD, the feed-forward resistors must be
selected in accordance with:
RFFN = RFFP ≥
VOUT
CEFF • fS • (VDD -0.7V)
Programming LED Current and Temperature Foldback
The AT9932 offers a temperature foldback feature that al-
lows programming the output current in accordance with the
temperature derating characteristics provided by the LED
manufacturers. A typical derating curve is shown in Figure
2.
Otherwise, the steady-state duty cycle D will not be reached,
and the LED driver will be unable to develop the desired
current.
I1
The feed-forward loop provides instantaneous response to
any transient at C1, and therefore achieves excellent rejec-
tion of the input voltage transients along the supply line. It is
inherently stable with proper selection of the damping net-
work Rd and Cd. Optimal selection of Rd and Cd is complex.
However, the worst case design of the damping circuit can
be performed under the assumption that VOUT(MAX) >> VIN(MIN)
for most automotive applications of the AT9932. The simpli-
fied equations given below produce very good results under
this assumption.
Cd =
9DMAX
(1 - DMAX
)
•
L1 • IO2
VIN(MIN)
Rd =
VIN(MIN)
3DMAXIO
In the cases where the above assumption is not valid, the
equations for Rd and Cd could still be used. However, they
may produce somewhat too conservative results. Power dis-
sipation in the damping resistor Rd can be computed as:
PRd
=
∆VC12
12 • Rd
where:
∆VC1 =
IOUT • D
fS • C1
is the peak-to-peak voltage ripple at the coupling capacitor
C1.
Output Over Voltage Protection
The AT9932 LED lamp driver supplies constant current to
the load. Therefore, an output circuit protection is needed to
prevent dramatic failures when the output load fails open. A
simple addition of a Zener diode (ZD1 in the Typical Applica-
tion Circuit on page 1) will limit the output voltage when the
output LED connection is lost.
I2
T1 T2
Figure 2. Temperature Derating Curve of LED Current
AVDD
NTC
AT9932
T1 DIV T2
DRP REF
FB
10KΩ
CRREF5
R6
RS
Figure 3. Output Current Feedback without Temperature
Foldback
When no temperature foldback is required, NTC and
T1 should be connected to AVDD, DIV and DRP should
be connected to GND. T2 still requires a resistor to GND
(10~100kΩ). No pins should be left floating. The DRP pin
can be connected to GND (Figure 3). In this case, the output
current of the AT9932 LED driver is programmed using the
following equation:
I1 =
VREF
RS
•
R6
R5
where VREF is voltage at the REF pin (VREF = 1.25V).
The same equation for calculating I1 is used when tempera-
ture fold-back is required, to calculate the current below T1.
When an external NTC resistor is connected (Figure 4), both
temperatures T1 and T2, as well as the current I2 can be ac-
curately programmed to maximize the light output of the
LED lamp.
The ratio of the resistor divider R2 /(R1 + R2) programs the
voltage at the NTC pin. The voltage at T1 is approximately
3.5V. The currents sourced by NTC and T1 are mirrored into
DRP in accordance with the following equation:
Supertex inc. ● 1235 Bordeaux Drive, Sunnyvale, CA 94089 ● Tel: 408-222-8888 ● www.supertex.com
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부품번호 | 상세설명 및 기능 | 제조사 |
AT9932 | Automotive Boost-Buck LED Lamp Driver IC | Supertex |
AT9933 | Hysteretic Boost-Buck LED Driver IC | Microchip |
DataSheet.kr | 2020 | 연락처 | 링크모음 | 검색 | 사이트맵 |