Download ELM901FxA 1A 2x Charge Pump LED Driver ELM901FxA-S

ELM901FxA 1A 2x Charge Pump LED Driver
■Description
ELM901FxA is a high current LED driver with internal automatic mode switch pump circuit of pass-through
mode (1x mode) and boost charge mode (2x mode) and constant current drive circuit; maximum output current
of ELM901 series can reach 1A. ELM901 series is ideally suited for high luminosity white LED electrical
applications which are powered by 1-cell lithium-ion/polymer battery. The required external parts of ELM901
series can be limited to the minimum of 3 capacitors and 3 programming resistors. With 4mm x 4mm & 3mm x
3mm QFN package, ELM901 series is possible to be assembled within limited space.
The sink current, which can be switched to 3 different kinds by enable signal during operation,of LED pin is
set by external programming resistors. For LED protection, it is possible to set high current lighting timer with
external resistor; the light will be turned off forcibly by timer (3 options among 0.2 sec. to 1 sec.).
Built-in soft-start circuitry makes ELM901 series be able to limit excessive power during start-up and switch
of 1x & 2x mode.
■Application
■Features
• Camera light supply
Low voltage operation
: 2.6V-4.4V
: 300μA(1x) 9mA(2x)
• High luminosity LED flashlight
Low power operation
Low standby current
: 1μA(max.)
: 1A (max.)
Large output current
LED protection
: high current lightening timer
Internal LED constant current circuit
: external resistance program
• Soft-start
: LED current start and switch of 1x & 2 x mode
• Package
: 4mm x 4mm QFN-16
3mm x 3mm QFN-16 (under development)
• Thermal shutdown function included
•
•
•
•
•
•
■Maximum absolute ratings
Parameter
VIN voltage
VO voltage
EN1,EN2 voltage
VO current, LED current
Operating temperature
Storage temperature
Symbol
Vin
Vo
Ven
Io, Iled
Top
Tstg
Limit
GND-0.3 to 6
GND-0.3 to 6
GND-0.3 to Vin+0.3
1500 *
-40 to +85
-40 to +125
Unit
V
V
V
mA
°C
°C
*:Based on long-term current density limitations. Assumes an operating duty cycle of ≤ 10% under absolute maximum conditions for
durations less than 10 seconds. Max current for continuous operation is 600mA.
■Selection Guide
ELM901FxA-S
Symbol
a
Package
b
Package type
c
d
Product version
Taping direction
F:QFN
A:4x4 QFN-16
B:3x3 QFN-16 (under development)
A
S : Refer to PKG file
11 - 1
ELM901 F x A - S
↑↑↑ ↑
abc d
ELM901FxA
1A 2x Charge Pump LED Driver
■Pin Configuration
4x4 QFN (TOP VIEW)
㪈㪉
㪈㪈
㪈㪇
4x4 QFN (BOTTOM VIEW)
㪐
㪐
㪈㪇
㪈㪈
㪈㪉
㪈㪊
㪏
㪏
㪈㪊
㪈㪋
㪎
㪎
㪈㪋
㪈㪌
㪍
㪍
㪈㪌
㪈㪍
㪌
㪌
㪈㪍
㪈
㪉
㪊
㪋
㪋
3x3 QFN (TOP VIEW)
㪈㪉
㪈㪈
㪈㪇
㪊
㪉
㪈
3x3 QFN (BOTTOM VIEW)
㪐
㪐
㪈㪇
㪈㪈
㪈㪉
㪈㪊
㪏
㪏
㪈㪊
㪈㪋
㪎
㪎
㪈㪋
㪈㪌
㪍
㪍
㪈㪌
㪈㪍
㪌
㪌
㪈㪍
㪈
㪉
㪊
㪋
㪋
㪊
㪉
Pin no.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Pin name
ISET2
ISET1
EN2
EN1
AGND
FS
VIN
PGND1
CM
PVIN
CP
NC
VO
NC
PGND2
LED
㪈
■Pin description
ISET2 : LED current setting 2
The pin that is for the connection of LED current setting resistor(Rset2) between ISET2-GND. The output
becomes 1.22V constantly when EN2 is high. The constant current of LED pin will be 3250x of the one
flows to ISET2.
(e.g.) when Rset2=6.8kΩ,Iled=1.22/6.8k×3250=583mA.
ISET1 : LED current setting 1
The pin that is for the connection of LED current setting resistor(Rset1) between ISET1-GND. The output
becomes 1.22V constantly when EN1 is high. The constant current of LED pin will be 3250x of the one
flows to ISET1.
(e.g.) when Rset1=20kΩ,Iled=1.22/20k×3250=198.3mA.
EN2 : on/off control 2
LED output current on/off control pin of set current of ISET2. This pin is pulled down to ground inside
the IC and the control logic is high active. The set current of ISET2 sinks from LED pin when this pin is
connected to VIN.
11 - 2
ELM901FxA
1A 2x Charge Pump LED Driver
EN1 : on/off control 1
LED output current on/off control pin of set current of ISET1. This pin is pulled down to ground inside
the IC and the control logic is high active. The set current of ISET1 sinks from LED pin when this pin is
connected to VIN.
AGND : internal analog circuit ground
This pin should be connected to GND of internal analog circuit and is connected in short circuit with internal
circuit on back pad. The connection to PGND1 & PGND2 is required and should be designed according to
the external wiring.
FS : fail safe setting
When EN1=EN2=1 continues for a period of time, fail safe function will turn down LED current forcibly.
This function aims for thermal protection of LED, and it is possible to be turned off. There are 3 timer
options according to the resistor connected between FS and GND since EN1=EN2=1 until LED current is
off: (1)1s when the resistor is short, (2)0.2s when the resistor is 20kΩ, and (3)0.5s when the resistor is 51kΩ.
This fail safe function becomes ineffective when it is short between FS and VIN or FS is open.
VIN : internal circuit power
This pin should be connected to the power pin of internal circuit. The connection to PVIN is required and
should be designed according to the external wiring; GND-connected ceramic capacitor( above 2.2uF) is
also necessary.
PGND1 : charge pump circuit ground
This pin should be connected to GND of charge pump circuit. The connection to AGND & PGND2 is
required and should be designed according to the external wiring.
CM : step-up capacitor connection( low potential)
This pin should be connected to the low potential of step-up capacitor. The wiring of step-up capacitor
should be connected between CM and CP as closely as possible; ELM recommends using 2.2μF capacitor.
PVIN : charge pump power
This pin is power supply of charge pump circuit. This pin should be connected to VIN according to the
external wiring.
CP : step-up capacitor connection( high potential)
This pin should be connected to the high potential of step-up capacitor. The wiring of step-up capacitor
should be connected between CM and CP as close as possible; ELM recommends using 2.2μF capacitor.
VO : step-up output
The output voltage is almost the same as VIN under 1x mode, while it becomes 5.5V under step-up mode.
This pin should be connected to LED anode.
PGND2 : LED current drive circuit ground
This pin should be connected to the GND of LED current drive circuit. The connection to AGND & PGND1
is required and should be designed according to the external wiring.
LED : constant current sink
To sink the output current which is set by ISET1 & ISET2. This pin should be connected to LED cathode.
11 - 3
ELM901FxA
1A 2x Charge Pump LED Driver
■Standard circuit
㪚㪉
2.2uF
12 NC 11 CP 10 PVIN 9 CM
•
13
Vo
㪭㪦
8
PGND1
㩷㩷㪚㪿㪸㫉㪾㪼㩷㫇㫌㫄㫇
䉼䊞䊷䉳䊘䊮䊒
㪚㪟㪘㪩㪞㪜㩷㪧㪬㪤㪧
4.7uF
㩷㪚㪈
14
NC
㪣㪜㪛
7
VIN
㪐㪇㪇㫂㪟㫑⊒ᝄེ
㪐㪇㪇㫂㩷㪟㫑㪦㪪㪚
㪐㪇㪇㫂㪟㫑㩷
㪦㪪㪚
㩷㩷㩷㩷㩷㪫㫀㫄㪼㫉
䉺䉟䊙䊷
㩷㩷㩷㩷㪫㪠㪤㪜㪩
15
PGND2
6
FS
㩷㩷㩷㩷
ቯ㔚ᵹ䉮䊮䊃䊨䊷䊦
㪚㪚㩷㪚㫆㫅㫋㫉㫆㫃
㩷㪚㪚㩷㪚㪦㪥㪫㪩㪦㪣
16
LED
• •
2.2uF
㩷㩷㩷㩷㩷㪚㪊
5
AGND
Rfs
1 㪠㪪㪜㪫㪉
㪠㪪㪜㪫㪈 3 EN2 4 EN1
Iset2 2 Iset1
Rset1
Rset2
㩷㩷㩷㩷㪧㪭㪠㪥
PVIN
㩷㩷㩷㩷
C+㪚㪧
•
■Block diagram
ً
Vin
㩷㪭㪠㪥
㪫㪿㪼㫉㫄㪸㫃
ㆊᾲ଻⼔
㫇㫉㫆㫋㪼㪺㫋㫀㫆㫅
㩷㩷㩷㪚㪤㪚䋭
Vo
㩷㪭㪦
㬍㪈㪆㬍㪉䉼䊞䊷䉳䊘䊮䊒
㩷㫏㪈㪆㫏㪉㩷㪺㪿㪸㫉㪾㪼㩷㫇㫌㫄㫇㩷
ً ًًً
ً
ً
ً ً
㩷㪪㫋㪼㫇㪄㫌㫇
᣹࿶࿁〝
㩷㪺㫀㫉㪺㫌㫀㫋
Vref
㩷㩷㩷㩷㪐㪇㪇㫂㪟㫑
㪐㪇㪇㫂㪟㫑⊒ᝄེ
㩷㩷㩷㩷㫆㫊㪺㫀㫃㫃㪸㫋㫆㫉
N1
㪜㪥㪈
N2
㪜㪥㪉
Vref(soft)
䊐䉢䊷䊦䊶䉶䊷䊐࿁〝
㩷㩷
㪝㪸㫀㫃㩷㫊㪸㪽㪼㩷㪺㫀㫉㪺㫌㫀㫋
PGND
㩷㪧㪞㪥㪛㪈
㬍㪈㪆㬍㪉ಾᦧ
㩷㫏㪈㪆㫏㪉㩷㫊㫎㫀㫋㪺㪿
䉮䊮䊃䊨䊷䊦
㩷㩷㪚㫆㫅㫋㫉㫆㫃㩷㫃㫆㪾㫀㪺
䊨䉳䉾䉪
ً
FS
㪝㪪
㩷㪪㪿㫆㫉㫋
⍴⛊଻⼔
㩷㫇㫉㫆㫋㪼㪺㫋㫀㫆㫅
ً
ً
㩷㪣㪜㪛
LED
ً
㩷㪛㫉㫆㫇㩷㫆㫌㫋㩷㪻㪼㫋㪼㪺㫋㫀㫆㫅
䊄䊨䉾䊒䊶䉝䉡䊃ᬌ಴
㪚㫌㫉㫉㪼㫅㫋㩷㫊㪼㫅㫊㪼
㔚ᵹ䉶䊮䉴
䉮䊮䊃䊨䊷䊦
㪺㫆㫅㫋㫉㫆㫃㩷
Iset1
㪠㪪㪜㪫㪈
Iset2
㪠㪪㪜㪫㪉
AGND
㪘㪞㪥㪛
11 - 4
PGND2
㪧㪞㪥㪛㪉
ELM901FxA
1A 2x Charge Pump LED Driver
■Operation
ELM901 is designed to drive high luminosity LED which is powered by 1 lithium-ion/polymer battery with
constant current. When the battery voltage is much higher than LED forward voltage, LED is lit by connecting
directly to the battery; output voltage is stepped up to 5.5V by internal charge pump circuit to light LED when
voltage drops. LED current is driven by the constant current circuit which is set by external programming resistors. With 2 types of LED current programming resistors, 3 current-driving options can be designed by different
combinations of enable circuit. ELM901A is capable of supplying output current up to 1A and thus able to provide high luminosity. To avoid LED burnout caused by longtime lighting by large current, the internal lighting
timer of ELM901A can shut down current forcibly. The timer only operates when maximum setting current is
on and can be set to 3 options-0.2s, 0.5s, 1s by external resistors connected to FS. This timer can be turned off
when it is short between FS and VIN or FS is open.
Operation right after power is supplied
ELM901 becomes standby operation when EN1=EN2=0 or open(standby); unde this operation, high
resistance PMOS switch between VIN and VO becomes ON. PMOS switch (=switch 4) between CP and
VO and NMOS switch (=switch 1) between CM and PGND1 also become on. Hence, output capacitor Co
and flying capacitor C1 are gradually charged through high resistance PMOS switch; it takes 5ms to fullcharge after the power is on. Rush current may happen when operation starts within 5ms after power is on.
Standby mode
In this mode, output capacitor Co and flying capacitor become fully charged, and through individual high
resistance PMOS switch, VIN is turned to be output mode. With maintenance of fully-charged mode during
standby situation, it is possible to avoid rush current when operation begins and lighten LED rapidly.
Start-up mode
During start-up, ELM901 detects VO short first; the low resistance switch between VIN-VO becomes on
and operates in 1x mode if short is not detected. When short is detected, Vo maintains the same condition as in standby mode, the output of LED also remains off while other internal circuits are operated normally. 1x mode is operated right after short is solved. It takes 30ms(typ.) from start-up to 1x mode output.
Vo=Vin under normal operation, and inrush current does not occur due to the charge of capacitor. When
abnormality (Vo>0.7V) such as short between VO and GND which is resulted from resistance of 10~1KΩ,
inrush current occurs due to the charge of capacitor. LED current becomes ON after 130μs(typ.) after starpup; it takes less than 100us since LED current becomes ON until the set current flows.
1x mode
When dropout of LED pin is detected under 1x mode, the operation switches to 2x mode automatically.
When LED current works under “low” current mode, the operation remains 1x mode for around 150ms
even if the dropout of LED pin is detected; if dropout is dissolved during this period of time, timer is reset
and 1x mode continues. When the operation is by “high” or “low+high” current, it becomes 2x mode after
2ms; if dropout is dissolved during this period of time, timer is reset and 1x mode continues. Dropout detection voltage is in proportion to Iled when it is above 240mA(typ.) and the voltage is regulated to 100mV
when Iled is small.
11 - 5
ELM901FxA
1A 2x Charge Pump LED Driver
Soft step-up
The operation becomes soft step-up by charge pump operation right after 2x mode starts. Rush current is
decreased by soft step-up which increases Vo straight. The current is controlled when Iled becomes 1/2 of
the setting during soft step-up. Iled is limited under 350mA(typ.) forcibly to avoid abrupt change of Iled
within 10us after step-up operation starts. Iled control current returns to the setting after step-up is finished.
2x mode
After switching to normal 2x mode, operation remains this mode until standby mode(EN1=EN2=GND)
starts. To work under 1x mode again, it is necessary to restart after switching to standby mode.
■Protection function
Thermal protection
When junction temperature becomes over 150°C, Vo output is turned to be OFF (only high resistance
PMOS switch is ON)thermal shutdown circuit and LED output is shut down by thermal shutdown circuit.
To shut down thermal protection, it is necessary to restart operation after returning to standby mode.
ISET1/ISET2 short protection
When EN1=0→1 during start-up, if Rset which is connected to ISET1 is under 3.9kΩ(setting current of
Iled is above 1A),LED current which is the same with[low] current is shut down. If ISET2 is under normal
operation under this situation, LED current which is the same with[high] current is flowed. When it is short
between ISET1 and GND under the operation that EN1=1, LED current limit is detected by 1.5A and shut
down without flowing to EN logic.
When EN2=0→1 during start-up, if Rset which is connected to ISET2 is under 3.9kΩ( setting current of
Iled is above 1A), LED current which is the same with[high] current is shut down. If ISET1 is under normal operation under this situation, LED current which is the same with[low] current is flowed. When it is
short between ISET2 and GND under the operation that EN2=1, LED current limit is detected by 1.5A and
shut down without flowing to EN logic.
LED current becomes 0 when [low]+[high]current reaches 1.5A under EN1=EN2=1 under the above-mentioned 2 situations.
VO short protection
When VO lowers to around 0.7V during operation, device shuts down the outputs of both Vo and LED; Vin
and Vo become connected by high resistance PMOS switch(standby output) under this situation. After VO
short is dissolved and Vo rises above 0.7V, outputs of Vo and LED restart. When VO short is detected under 2x mode, the operation switches to standby mode.
Fail safe function
Fail safe function refers to the function that the output of LED is turned to be OFF automatically when
“low+high” current(EN1=EN2=1) continues for certain period of time. To dissolve the function that LED
output is turned to be OFF forcibly, it is necessary to switch EN1=EN2=1 to other modes. 3 options are
available for FS time; FS time is set by external resistors (Rfs). This function can be turned off by setting
short between FS and VIN pins or FS to be open.
11 - 6
ELM901FxA
1A 2x Charge Pump LED Driver
■Electrical characteristics
When conditions are not mentioned specifically,Vin=3.6V, Cin=C1=2.2μF, Co=4.7μF, Ta=25°C
Parameter
Symbol
Condition
Min.
Typ. Max.
Unit
Input voltage range
Vin
2.6
4.4
V
current consumption under
Iqs1 1x mode, Iled=0mA
300
550
μA
still condition 1
current consumption under
Iqs2 2x mode, Iled=0mA
9
16
mA
still condition 2
Standby current
Isd
EN1=EN2=0V
0.1
1.0
μA
LED current
LED current ratio1
typ.×
typ.×
Iled1 Vin=3.8V, Iled=200mA, Vf=3.3V
3250
mA/mA
(Iled/Iset1/2)
0.96
1.04
LED current ratio2
Vin=3.3 to 4.4V,
typ.×
typ.×
Iled2
3250
mA/mA
(Iled/Iset1/2)
Iled=200 to 800mA
0.90
1.10
Vled1 Mode switch threshold voltage,
Iled dropout voltage1
125
225
mV
(Min.) Iled=300mA
Vled2 Mode switch threshold voltage,
Iled dropout voltage2
80
100
120
mV
(Min.) Iled=150mA
Mode switch delay time1
Td1 EN1=High, EN2=Low
100
150
200
ms
Mode switch delay time2
Td2 EN1=Low or High, EN2=High
1
2
3
ms
since EN is ON until LED current
LED current on time
LED(on)
50
130
250
μs
starts
Iled Vin=3.3V, EN1=EN2=High, set
Current capability
900
mA
(Max.) Iled=1A, VF=4.6V
LED current stablize time1
TIled1 Iled=0mA→200mA
40
μs
LED current stablize time2
TIled2 Iled=200mA→700mA
60
μs
LED current during soft
Iled
set Iled=700mA
250
350
450
mA
step-up
(soft)
Charge pump
Soft step-up
Tsoft Iled=700mA, Vo=3.7V→5.2V
75
150
300
μs
1x mode output voltage
Vo(x1) Iled=0mA
Vin
V
typ.×
typ.×
2x mode output voltage
Vo(x2) Iled=0mA
5.5
V
0.95
1.05
1x mode output impedance
Ro(x1) Vin=3.4V
0.25
0.37
Ω
(2Vin-Vo)/Io, Vin=3.2V,
2x mode output impedance
Ro(x2)
1.70
2.55
Ω
Vo=5.1V
Oscillation frequency
Fosc
0.72
0.90
1.08
MHz
EN1, EN2
Output on control voltage
Vc(ON) Vin=2.9 to 4.4V, each pin
0.95
V
Output off control voltage
Vc(OFF) Vin=2.9 to 4.4V, each pin
0.45
V
EN bias current
Ic(ON) Ven=3.6V, each pin
20
50
μA
ISET1, ISET2
Reference voltage
Vref Iset=50μA, each pin
1.202 1.220 1.238
V
ISET set current
Iset
each pin
310
μA
11 - 7
ELM901FxA
Parameter
Short protection circuit
1A 2x Charge Pump LED Driver
Symbol
Condition
Min.
ISET1&2 turn Iled to be OFF
Iled
Iled limit when ISET is short
for short protection, Vin=3.9V,
(short)
Vled=1.0V, 2x operation
VO short protection detection
Vo
Iled is OFF when short protection
0.45
voltage
(short) is activated
VO short current
Ishort Vin=3.6V
Thermal protection circuit
Iled is OFF when thermal
Thermal protection circuit
OHP
protection circuit is activated
Fail safe circuit
Tfs
Fail safe set range
0.2
(range)
Fail
safe
function
is
OFF
when
Fail safe time1
Tfs1 *
0.8
FS-VIN is short or open.
Fail safe time2
Tfs2
0.16
Fail safe time3
Tfs3
0.4
Fail safe current
Ifs
10
FS threshold voltage1
Vfs1
0.12
FS threshold voltage2
Vfs2
0.405
FS threshold voltage3
Vfs3
1.08
Parameter
EN logic & LED current
EN logic
Standby( output OFF)
Low current
High current
Low+High current
Max.
Unit
1.5
0.60
A
0.95
V
30
mA
150
°C
1.0
0.20
0.5
15
0.15
0.450
1.22
1.0
s
1.2
0.24
0.6
20
0.18
0.495
1.36
s
s
s
μA
V
V
V
Condition
EN1
0
1
0
1
EN2
0
0
1
1
* EN1 & EN2 will be in standby mode when being
pulled down to be open.
■Marking
• 4x4 QFN-16 package : ELM901FAA
㪜㪣㪤
㪐㪇㪈㪝㪘㪘
㪸㪹㪺
Typ.
Names
Assembly lot No. :
000 to 999
11 - 8
ELM901FxA
1A 2x Charge Pump LED Driver
■Typical characteristics
Dropout Voltage-Iled
EFFICIENCY-Vin
LED = LUMILEDS LXHL-LW3C
ILED=
200mA
EFFICIENCY (%)
90
400mA
0.5
600mA
Dropout Voltage (V)
100
80
70
60
50
800mA
40
30
0.4
0.3
0.2
0.1
20
10
0
2.6 2.8 3 3.2 3.4 3.6 3.8 4 4.2 4.4
200
Iled-Rset
1000
Iled-Vled
900
900
800
800
700
700
Iled (mA)
1000
Iled (mA)
800
Iled (mA)
1000
600
500
400
Iled=800mA
600mA
600
500
400mA
400
300
300
200
200
100
200mA
100mA
100
0
0
0 20 40 60 80 100 120 140 160 180 200
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Rset (kǡ)
Vled (V)
1x Mode Output Resistance - Top
2x Mode Output Resistance - Top
0.25
Vin=3.3V
0.2
0.15
Vin=3.6V
Vin=3.9V
0.1
0.05
0
-40
Vin=3.2V, Vo=4.8V
2.5
2x Mode Output Resistance (˖)
1x Mode Output Resistance (˖)
600
400
Vin (V)
-20
0
20
40
60
2
1.5
1
0.5
0
-40
80
Top (ദ)
-20
0
20
40
Top (ദ)
11 - 9
60
80
ELM901FxA
1A 2x Charge Pump LED Driver
Frequency - Vin
Isd-Vin
0.1
940
920
0.08
Frequency (kHz)
Isd (˩A)
Top=85ദ
0.06
0.04
Top=25ദ
0.02
Top=85ദ
Top=25ദ
900
880
Top= -40ദ
860
840
Top=웎40ദ
0
2.6 2.8 3 3.2 3.4 3.6 3.8 4 4.2 4.4
820
2.6 2.8 3 3.2 3.4 3.6 3.8 4 4.2 4.4
Vin (V)
Vin (V)
Vref-Top
Iled/Iset Ratio-Top
1.24
3300
3280
Vref (V)
Iled/Iset Ratio
1.23
1.22
1.21
1.2
-40
3260
3240
3220
-20
0
20
40
60
3200
-40
80
-20
0
Top (ദ)
60
80
0.9
EN Thereshold Voltage (V)
EN Pin Input Current (uA)
40
EN Threshold Voltage-Top
EN Pin Input Current-Top
30
25
20
15
10
-40
20
Top (ദ)
-20
0
20
40
60
0.8
0.7
0.6
0.5
-40
80
Top (ദ)
-20
0
20
40
Top (ദ)
11 - 10
60
80
ELM901FxA
1A 2x Charge Pump LED Driver
Iled Start Response
Iled/Iset Ratio-Iled
Vin=3.6V, Iled=0mAψ200mA
3350
Iled (mA)
300
Iled/Iset Ratio
3300
Top=85ദ
200
100
0
3250
Top=25ദ
V(EN1) : 0V ψ 3.6V
Top= -40ദ
3200
3150
600
400
200
800
0
80
160
1x to 2x Mode Switch Response
Iled, Vo Ripple Voltage
40
Iled
Iled (mA)
Iled (mA)
400
Vin=3.6V, Iled=800mA
400
0
Vo
Vo, V(EN2)
(2V/Div)
320
Time (us)
Vin=3.6V, Iled=200mAඎ800mA
800
240
Iled (mA)
Iled A/C Coulpled
20
0
-20
-40
200
Vo A/C Coulpled
V(EN2) : 0V ඎ 3.6V
100
0
-100
0
0.8
1.6
2.4
3.2
4
0
Time (ms)
2
4
6
Time (us)
11 - 11
8
-200
10
Vo (mV)
0