MAXIM MAX8834ZEWP+T

19-4421; Rev 0; 4/09
KIT
ATION
EVALU
LE
B
A
IL
A
AV
Adaptive Step-Up Converters
with 1.5A Flash Driver
The MAX8834Y/MAX8834Z flash drivers integrate a
1.5A PWM DC-DC step-up converter and three programmable low-side, low-dropout LED current regulators. The step-up converter features an internal
switching MOSFET and synchronous rectifier to
improve efficiency and minimize external component
count. An I2C interface provides flexible control of stepup converter output voltage setting, movie/flash mode
selection, flash timer duration settings, and current regulator settings. The MAX8834Y/MAX8834Z operate
down to 2.5V, making them future proof for new battery
technologies.
The MAX8834Y/MAX8834Z consist of two current regulators for the flash/movie mode. Each current regulator can
sink 750mA in flash mode and 125mA in movie mode.
The MAX8834Y/MAX8834Z also integrate a 16mA lowcurrent regulator that can be used to indicate camera
status. The indicator current regulator includes programmable ramp and blink timer settings. A programmable
input current limit, invoked using the GSMB control,
reduces the total current drawn from the battery during
PA transmit events. This ensures the flash current is set
to the maximum possible for any given operating condition. Additionally, the MAX8834Y/MAX8834Z include a
MAXFLASH* function that adaptively reduces flash current during low battery conditions to help prevent system
undervoltage lockup.
Other features include an optional NTC input for fingerburn protection and open/short LED detection. The
MAX8834Y switches at 2MHz, providing best overall
efficiency. The MAX8834Z switches at 4MHz, providing
smallest overall solution size. The MAX8834Y/
MAX8834Z are available in a 20-bump, 0.5mm pitch
WLP package (2.5mm x 2.0mm).
Features
♦ 2.5V to 5.5V Operation Range
♦ Step-Up DC-DC Converter
1.5A Guaranteed Output Current
Adaptive or I2C Programmable Output Voltage
2MHz and 4MHz Switching Frequency Options
♦ Two Flash/Movie LED Current Regulators
I2C Programmable Flash and Movie Current
Low-Dropout Voltage (110mV max) at 500mA
♦ LED Indicator Current Regulator
I2C Programmable Output Current
Ramp and Blink Timers for Indicator Mode
Low-Dropout Voltage (130mV max) at 16mA
♦ I2C Programmable Safety and Watchdog Timers
♦ GSM Blank Logic Input
♦ MAXFLASH System Lockup Protection
♦ Remote Temperature Sensor Input
♦ Open/Short LED Detection
♦ Thermal Shutdown Protection
♦ < 1µA Shutdown Current
♦ 20-Bump, 0.5mm Pitch, 2.5mm x 2.0mm WLP
Applications
Cell Phones and Smart Phones
PDAs, Digital Cameras, and Camcorders
Typical Operating Circuit
1μH OR 2.2μH
INPUT
2.5V TO 5.5V
LX
IN
10μF
AGND
PGND
Ordering Information
COMP
SWITCHING
TEMP
PIN-PACKAGE FREQUENCY
RANGE
(MHz)
-40°C to 20 WLP
MAX8834YEWP+T
+85°C (2.5mm x 2.0mm)
MAX8834ZEWP+T
OUT
10μF
*Patent pending.
PART
PROGRAMMABLE
OUTPUT
3.7V TO 5.2V
-40°C to 20 WLP
+85°C (2.5mm x 2.0mm)
2
PA_TXON
1.5A TOTAL
FLASH
I2C
GSMB
VLOGIC
0.1μF
INDLED
16mA INDICATOR
LED_EN
SCL
SDA
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
FLED1
FLED2
FLASH ON
4
MAX8834Y
MAX8834Z
VDD
FGND
NTC
FINGER-BURN
PROTECTION
Pin Configuration appears at end of data sheet.
________________________________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
1
MAX8834Y/MAX8834Z
General Description
MAX8834Y/MAX8834Z
Adaptive Step-Up Converters
with 1.5A Flash Driver
ABSOLUTE MAXIMUM RATINGS
IN, OUT, NTC to AGND .........................................-0.3V to +6.0V
VDD to AGND.........................................................-0.3V to +4.0V
SCL, SDA, LED_EN, GSMB to AGND ........-0.3V to (VDD + 0.3V)
FLED1, FLED2, INDLED to FGND ............-0.3V to (VOUT + 0.3V)
COMP to AGND ...........................................-0.3V to (VIN + 0.3V)
PGND, FGND to AGND .........................................-0.3V to +0.3V
ILX Current (rms) ......................................................................3A
Continuous Power Dissipation (TA = +70°C)
(derate 17.5mW/°C above +70°C) .............................1410mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Bump Temperature* (soldering) ......................................+260°C
*This device is constructed using a unique set of packaging techniques that impose a limit on the thermal profile the device can be exposed to during board
level solder attach and rework. This limit permits only the use of the solder profiles recommended in the industry-standard specification, JEDEC 020A, paragraph 7.6, Table 3 for IR/VPR and Convection reflow. Preheating is required. Hand or wave soldering is not allowed.
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(VIN = 3.6V, VAGND = VPGND = VFGND = 0V, VDD = 1.8V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at
TA = +25°C.) (Note 1)
MAX
UNITS
IN Operating Voltage
PARAMETER
2.5
5.5
V
VDD Operating Range
1.62
3.6
V
1.55
V
VDD Undervoltage Lockout
(UVLO) Threshold
CONDITIONS
MIN
VDD falling
1.25
1.4
VIN falling
2.15
2.3
VDD UVLO Hysteresis
IN UVLO Threshold
TYP
50
IN UVLO Hysteresis
mV
2.45
50
IN Standby Supply Current
VSCL = VSDA = VDD, VIN = 5.5V, I2C ready
VDD Standby Supply Current
(All Outputs Off, I2C Enabled)
VSCL = VSDA = VDD = 3.6V, I2C ready
4
V
mV
1
μA
7
μA
LOGIC INTERFACE
LED_EN, GSMB
Logic Input-High Voltage
VDD = 1.62V to 3.6V
Logic Input-Low Voltage
VDD = 1.62V to 3.6V
SCL, SDA
1.4
V
0.7 x
VDD
LED_EN, GSMB
0.4
0.3 x
VDD
SCL, SDA
LED_EN Minimum High Time
(LED_EN is Internally Sampled
by a 1MHz Clock)
LED_EN Propagation Delay
From LED_EN going high to rising edge on current
regulator
LED_EN and GSMB Pulldown
Resistor
Logic Input Current (SCL, SDA)
2
VIL = 0V or VIH = 3.6V
TA = +25°C
TA = +85°C
V
1
μs
3
μs
400
800
1600
-1
0.01
+1
0.1
_______________________________________________________________________________________
k
μA
Adaptive Step-Up Converters
with 1.5A Flash Driver
(VIN = 3.6V, VAGND = VPGND = VFGND = 0V, VDD = 1.8V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at
TA = +25°C.) (Note 1)
PARAMETER
Shutdown Leakage Current
CONDITIONS
TA = +25°C
IN and VDD in UVLO,
VLED_EN = VGSMB = 0V
MIN
TYP
MAX
-1
0.01
+1
TA = +85°C
0.1
UNITS
μA
I2C INTERFACE
SDA Output Low Voltage
I SDA = 3mA
0.03
I2C Clock Frequency
Bus-Free Time Between STOP
and START
tBUF
1.3
Hold Time Repeated START
Condition
tHD_STA
0.6
0.4
V
400
kHz
μs
0.1
μs
SCL Low Period
tLOW
1.3
0.2
μs
SCL High Period
tHIGH
0.6
0.2
μs
Setup Time Repeated START
Condition
t SU_STA
0.6
0.1
μs
SDA Hold Time
tHD_DAT
0
-0.01
μs
SDA Setup Time
t SU_DAT
100
50
ns
Setup Time for STOP Condition
t SU_STO
0.6
0.1
μs
100mV steps
3.7
STEP-UP DC-DC CONVERTER
OUT Voltage Range
OUT Voltage Accuracy
No load, VOUT = 5V
OUT Overvoltage Protection
When running in adaptive mode
Adaptive Output Voltage
Regulation Threshold
IFLED1 = IFLED2 = 492.24mA setting, IINDLED = 16mA
5.2
V
-2.75
±0.5
+2.75
%
5.2
5.35
5.5
V
150
-15
PGOOD Window Comparator
VOUT = 5V, in programmable mode
Line Regulation
VIN = 2.5V to 4.2V
0.1
%/V
Load Regulation
I OUT = 0mA to 1500mA
0.5
%/A
nFET Current Limit
-12.5
mV
-10
3.6
%
A
LX nFET On-Resistance
LX to PGND, ILX = 200mA
0.055
0.130
LX pFET On-Resistance
LX to OUT, ILX = 200mA
0.12
0.200
LX Leakage
VLX = 5.5V
TA = +25°C
0.1
1
TA = +85°C
0.1
Input Current Limit Range During
GSMB Trigger
50
Input Current Limit Step Size
During GSMB Trigger
Input Current Limit Accuracy
800
50
I ILIM = 100mA, in dropout mode
MAX8834Y
Operating Frequency, No Load
MAX8834Z
-15
TA = +25°C
1.8
TA = -40°C to +85°C
1.6
TA = +25°C
3.6
TA = -40°C to +85°C
3.2
μA
mA
mA
+15
2
2.2
4
4.4
2.4
%
MHz
4.8
_______________________________________________________________________________________
3
MAX8834Y/MAX8834Z
ELECTRICAL CHARACTERISTICS (continued)
MAX8834Y/MAX8834Z
Adaptive Step-Up Converters
with 1.5A Flash Driver
ELECTRICAL CHARACTERISTICS (continued)
(VIN = 3.6V, VAGND = VPGND = VFGND = 0V, VDD = 1.8V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at
TA = +25°C.) (Note 1)
PARAMETER
CONDITIONS
MIN
69
TYP
MAX
UNITS
Maximum Duty Cycle
VOUT = 4.5V
75
%
Minimum Duty Cycle
VOUT = 4.5V
7.5
%
COMP Transconductance
VCOMP = 1.5V
55
μS
120
10
k
Step-up off, FLED1/FLED2 on, supply current for each
current source
0.6
mA
Flash
750
Movie
125
COMP Discharge Resistance
During shutdown or UVLO, from COMP to AGND
OUT Discharge Resistance
During shutdown or UVLO, from OUT to LX
FLED1/FLED2 CURRENT REGULATOR
IN Supply Current
Maximum Current Setting
23.44mA setting
Current Accuracy
492.24mA setting
750mA setting
Current Regulator Dropout
(Note 2)
FLED1/FLED2 Leakage in
Shutdown
TA = +25°C
-5
TA = +25°C
-2.5
TA = -40°C to +85°C
-4
TA = -40°C to +85°C
-10
+20
±0.5
+2.5
+4
+5
492.24mA setting
110
93.75mA setting
VFLED1 = VFLED2 = 5.5V
mA
TA = +25°C
-1
TA = +85°C
50
100
0.01
+1
0.1
%
%
%
mV
μA
INDLED CURRENT REGULATOR
IN Supply Current
Step-up converter off, INDLED on
0.6
mA
Maximum Current Setting
16
mA
0.5mA setting
Current Accuracy
Current Regulator Dropout
INDLED Leakage in Shutdown
16mA setting
TA = +25°C
-10
TA = +25°C
-3
TA = -40°C to +85°C
-5
TA = +25°C
-1
16mA setting (Note 2)
VINDLED = 5.5V
TA = +85°C
+10
%
+3
%
+5
%
55
130
mV
0.01
+1
±0.5
0.1
μA
PROTECTION CIRCUITS
NTC BIAS Current
NTC Overtemperature Detection
Threshold
VNTC falling, 100mV hysteresis, NTC_CNTL[2:0] = 100
NTC Short Detection Threshold
VNTC falling
19.4
20
20.6
μA
388
400
412
mV
100
Flash Duration Timer Range
In 50ms steps (Note 3)
Flash Duration Timer Accuracy
(400ms Setting)
TA = +25°C
360
50
TA = -40°C to +85°C
320
mV
800
400
440
480
ms
ms
Minimum Flash Duration
FLASH_EN[2:0] = 1XX
2
ms
Flash Safety Timer Reset Inhibit
Period
From falling edge of LED_EN until flash safety timer is
reset
30
ms
Watchdog Timer Range
In 4s steps
4
4
_______________________________________________________________________________________
16
s
Adaptive Step-Up Converters
with 1.5A Flash Driver
(VIN = 3.6V, VAGND = VPGND = VFGND = 0V, VDD = 1.8V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at
TA = +25°C.) (Note 1)
PARAMETER
MIN
TYP
MAX
Watchdog Timer Accuracy
(4s setting)
TA = +25°C
CONDITIONS
3.6
4
4.4
TA = -40°C to +85°C
3.2
Open LED Detection Threshold
FLED1, FLED2, INDLED enabled
100
Shorted LED Detection Threshold FLED1, FLED2, INDLED enabled
Open and Short Debounce Timer
4.8
From LED open or short detected until LED current
regulator is disabled
Thermal-Shutdown Hysteresis
Thermal Shutdown
UNITS
s
mV
VOUT 1V
V
30
ms
20
°C
+160
°C
MAXFLASH
Low-Battery Detect Threshold
Range
33mV steps
2.5
Low-Battery Voltage Threshold
Accuracy
±2.5
Low-Battery Voltage Hysteresis
Programmable Range
100
Low-Battery Voltage Hysteresis
Step Size
Low-Battery Reset Time
3.4
V
%
200
100
mV
mV
LB_TMR[1:0] = 00
200
250
300
LB_TMR[1:0] = 01
400
500
600
μs
Note 1: All devices are 100% production tested at TA = +25°C. Limits over the operating temperature range are guaranteed by
design.
Note 2: LED current regulator dropout voltage is defined as the voltage when current drops 10% from the current level measured at
0.6V.
Note 3: Flash duration is from rising edge of LED_EN until IFLED = 0A (safety time in one-shot mode).
Note 4: The adaptive output voltage regulation threshold is individually set on each device to 75mV above the dropout voltage of
the LED current regulators. This ensures minimum power dissipation on the IC during a flash event. The dropout voltage
chosen is the highest measured dropout voltage of FLED1, FLED2, and INDLED.
_______________________________________________________________________________________
5
MAX8834Y/MAX8834Z
ELECTRICAL CHARACTERISTICS (continued)
Typical Operating Characteristics
(Circuit of Figure 1, VIN = 3.6V, VOUT = 3.8V, VDD = 3.0V, TA = +25°C, unless otherwise noted.)
VOUT = 3.8V
IOUT = 750mA
60
VOUT = 5V
IOUT = 250mA
VOUT = 3.8V
IOUT = 250mA
20
0
2.5
3.0
VOUT = 5V
IOUT = 250mA
40
VOUT = 3.8V
IOUT = 250mA
30
20
FOR VIN > VOUT, VOUT INCREASES ABOVE THE
PROGRAMMED VALUE DUE TO THE MINIMUM
DUTY CYCLE CONSTRAINT.
10
3.5
4.0
4.5
VOUT = 5V
VOUT = 3.8V IOUT = 16mA
IOUT = 16mA
0
5.0
2.5
3.0
3.5
4.0
4.5
MAX8834Y/Z toc03
VIN = 2.5V
60
40
20
FOR VIN > VOUT, VOUT INCREASES ABOVE THE
PROGRAMMED VALUE DUE TO THE MINIMUM
DUTY CYCLE CONSTRAINT.
10
VIN = 3.2V
0
1
5.0
10
100
1000
10,000
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
OUTPUT CURRENT (mA)
STEP-UP CONVERTER EFFICIENCY
vs. OUTPUT CURRENT (MAX8834Z)
STEP-UP CONVERTER SUPPLY CURRENT
vs. SUPPLY VOLTAGE
STEP-UP CONVERTER SUPPLY CURRENT
vs. TEMPERATURE
100
80
VIN = 3.2V
60
VIN = 2.5V
15
VOUT = 3.8V
12
SUPPLY CURRENT (mA)
VIN = 3.6V
40
20
20
VOUT = 5V
MAX8834Z
9
MAX8834Y
6
15
MAX8834Z
10
MAX8834Y
5
3
0
0
1
10
100
10,000
1000
2.5
3.0
OUTPUT CURRENT (mA)
3.5
4.0
4.5
5
IFLED1 = 492.19mA
IFLED2 = 125mA
0
IFLED2 = 492.19mA
IINDLED = 16mA
IFLED1 = 750mA
IFLED2 = 750mA
10
8
LED CURRENT ACCURACY (%)
IFLED1 = 125mA
IFLED2 = 125mA
6
IFLED1 = 125mA
4
4.0
4.5
INPUT VOLTAGE (V)
5.0
5.5
IFLED1 = 492.19mA
0
IINDLED = 16mA
-2
IFLED1 = 750mA
-4
-6
IFLED2 = 492.19mA
IFLED2 = 750mA
VOUT = 5V
-10
-10
3.5
35
2
-8
VOUT = 5V
3.0
10
TEMPERATURE (°C)
LED CURRENT ACCURACY
vs. TEMPERATURE
MAX8834Y/Z toc07
LED CURRENT ACCURACY (%)
10
2.5
-15
SUPPLY VOLTAGE (V)
LED CURRENT ACCURACY
vs. INPUT VOLTAGE
-5
-40
5.0
MAX8834Y/Z toc08
0
6
80
60
50
VIN = 3.6V
MAX8834Y/Z toc06
30
VOUT = 5V
IOUT = 750mA
SUPPLY CURRENT (mA)
40
VOUT = 5V
IOUT = 750mA
70
MAX8834Y/Z toc05
50
VOUT = 5V
IOUT = 16mA
VOUT = 3.8V
IOUT = 750mA
80
EFFICIENCY (%)
70
90
MAX8834Y/Z toc04
EFFICIENCY (%)
80
100
MAX8834Y/Z toc02
VOUT = 3.8V
IOUT = 16mA
100
MAX8834Y/Z toc01
100
90
STEP-UP CONVERTER EFFICIENCY
vs. OUTPUT CURRENT (MAX8834Y)
STEP-UP CONVERTER EFFICIENCY
vs. INPUT VOLTAGE (MAX8834Z)
EFFICIENCY (%)
STEP-UP CONVERTER EFFICIENCY
vs. INPUT VOLTAGE (MAX8834Y)
EFFICIENCY (%)
MAX8834Y/MAX8834Z
Adaptive Step-Up Converters
with 1.5A Flash Driver
-40
-15
10
35
60
TEMPERATURE (°C)
_______________________________________________________________________________________
85
60
85
Adaptive Step-Up Converters
with 1.5A Flash Driver
OUTPUT VOLTAGE ACCURACY
vs. TEMPERATURE
0.2
0
MAX8834Y, IOUT = 250mA
-0.2
-0.4
MAX8834Z, IOUT = 250mA
-0.6
MAX8834Y/Z toc10
MAX8834Y, NO LOAD
5
OSCILLATOR FREQUENCY (MHz)
VOUT = 5V
MAX8834Z, NO LOAD
0.4
MAX8834Y/Z toc09
OUTPUT VOLTAGE ACCURACY (%)
0.6
INTERNAL OSCILLATOR FREQUENCY
vs. SUPPLY VOLTAGE
MAX8834Z
4
3
2
MAX8834Y
1
0
-40
-15
10
35
60
85
2.5
3.0
3.5
4.0
4.5
5.0
TEMPERATURE (°C)
SUPPLY VOLTAGE (V)
STARTUP WAVEFORM
(MAX8834Y, VOUT = 5V)
STARTUP WAVEFORM
(MAX8834Y, ADAPTIVE MODE)
MAX8834Y/Z toc11
5V
VOUT
VLX
MAX8834Y/Z toc12
2V/div
VOUT
2V/div
2V/div
VLX
2V/div
VOUT = 5V
ILED1 = 31.25mA
ILX
5.5
ADAPTIVE MODE
ILED1 = 31.25mA
ILX
500mA/div
500mA/div
VCOMP
1V/div
1V/div
VCOMP
1ms/div
1ms/div
STARTUP WAVEFORM
(MAX8834Z, VOUT = 5V)
STARTUP WAVEFORM
(MAX8834Z, ADAPTIVE MODE)
MAX8834Y/Z toc13
5V
VOUT
VLX
MAX8834Y/Z toc14
2V/div
VOUT
2V/div
2V/div
VLX
2V/div
VOUT = 5V
ILED1 = 31.25mA
ILX
ADAPTIVE MODE
ILED1 = 31.25mA
ILX
500mA/div
500mA/div
VCOMP
1V/div
1ms/div
1V/div
VCOMP
1ms/div
_______________________________________________________________________________________
7
MAX8834Y/MAX8834Z
Typical Operating Characteristics (continued)
(Circuit of Figure 1, VIN = 3.6V, VOUT = 3.8V, VDD = 3.0V, TA = +25°C, unless otherwise noted.)
MAX8834Y/MAX8834Z
Adaptive Step-Up Converters
with 1.5A Flash Driver
Typical Operating Characteristics (continued)
(Circuit of Figure 1, VIN = 3.6V, VOUT = 3.8V, VDD = 3.0V, TA = +25°C, unless otherwise noted.)
SHUTDOWN WAVEFORM
(MAX8834Y, VOUT = 5V)
SHUTDOWN WAVEFORM
(MAX8834Y, ADAPTIVE MODE)
MAX8834Y/Z toc15
VOUT
5V
VLX
VOUT = 5V
ILED1 = 31.25mA
ILX
MAX8834Y/Z toc16
2V/div
VOUT
2V/div
2V/div
VLX
2V/div
500mA/div
1V/div
VCOMP
ADAPTIVE MODE
ILED1 = 31.25mA
ILX
VCOMP
1V/div
400μs/div
400μs/div
SHUTDOWN WAVEFORM
(MAX8834Z, VOUT = 5V)
SHUTDOWN WAVEFORM
(MAX8834Z, ADAPTIVE MODE)
MAX8834Y/Z toc17
VOUT
MAX8834Y/Z toc18
2V/div
5V
2V/div
VLX
VOUT = 5V
ILED1 = 31.25mA
ILX
VCOMP
500mA/div
500mA/div
1V/div
VOUT
2V/div
VLX
2V/div
ADAPTIVE MODE
ILED1 = 31.25mA
ILX
500mA/div
VCOMP
1V/div
400μs/div
400μs/div
LIGHT-LOAD SWITCHING WAVEFORMS
(MAX8834Y)
LIGHT-LOAD SWITCHING WAVEFORMS
(MAX8834Z)
MAX8834Y/Z toc20
MAX8834Y/Z toc19
2V/div
VLX
2V/div
VLX
0V
0mA
200mA/div
ILX
VOUT = 5V
IOUT = 16mA
VOUT
AC RIPPLE
400ns/div
8
20mV/div
0V
0mA
200mA/div
ILX
VOUT = 5V
IOUT = 16mA
VOUT
AC RIPPLE
20mV/div
400ns/div
_______________________________________________________________________________________
Adaptive Step-Up Converters
with 1.5A Flash Driver
HEAVY-LOAD SWITCHING WAVEFORMS
(MAX8834Y)
HEAVY-LOAD SWITCHING WAVEFORMS
(MAX8834Z)
MAX8834Y/Z toc21
MAX8834Y/Z toc22
2V/div
VLX
2V/div
VLX
0V
0V
1.5A
ILX
500mA/div
VOUT = 5V
IOUT = 1A
VOUT
AC RIPPLE
50mV/div
500mA/div
1.5A
ILX
VOUT = 5V
IOUT = 1A
VOUT
AC RIPPLE
50mV/div
400ns/div
400ns/div
GSMB WAVEFORM
MAXFLASH FUNCTION
MAX8834Y/Z toc23
VOUT = 5V
ILIM = 500mA
IFLED1 = IFLED2 = 515.63mA
tHC_TRM = 80μs
VGSMB
IIN
MAX8834Y/Z toc24
3.6V
2V/div
VIN
VIN DROPS
BELOW THE
THRESHOLD
VOLTAGE
3.6V
200mV/div
1A/div
VIN INCREASES TO
THE THRESHOLD
IFLED1
500mA/div
IFLED1
IFLED2
200mV/div
1ms/div
10ms/div
OUTPUT VOLTAGE LINE REGULATION
(MAX8834Y)
OUTPUT VOLTAGE LINE REGULATION
(MAX8834Z)
VOUT = 5V
VOUT = 5V
5.01
OUTPUT VOLTAGE (V)
5.01
IOUT = 16mA
5.00
4.99
IOUT = 250mA
MAX8834Y/Z toc26
5.02
MAX8834Y/Z toc25
5.02
OUTPUT VOLTAGE (V)
0mA
500mA/div
VOUT = 5V
IFLED1 = 750mA
VLB_TH = 3.0V
VLB_HYS DISABLED
tTMR_DUR = 50ms
IOUT = 16mA
5.00
4.99
IOUT = 250mA
IOUT = 750mA
IOUT = 750mA
4.98
4.98
4.97
4.97
2.5
3.0
3.5
INPUT VOLTAGE (V)
4.0
4.5
2.5
3.0
3.5
4.0
4.5
INPUT VOLTAGE (V)
_______________________________________________________________________________________
9
MAX8834Y/MAX8834Z
Typical Operating Characteristics (continued)
(Circuit of Figure 1, VIN = 3.6V, VOUT = 3.8V, VDD = 3.0V, TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics (continued)
(Circuit of Figure 1, VIN = 3.6V, VOUT = 3.8V, VDD = 3.0V, TA = +25°C, unless otherwise noted.)
OUTPUT VOLTAGE LOAD REGULATION
(MAX8834Y)
OUTPUT VOLTAGE LOAD REGULATION
(MAX8834Z)
5.00
4.99
4.98
MAX8834Y/Z toc28
5.01
OUTPUT VOLTAGE (V)
5.01
4.97
5.00
4.99
4.98
4.97
VOUT = 5V
VOUT = 5V
4.96
4.96
1
10
100
1000
10,000
1
10
100
1000
OUTPUT CURRENT (mA)
INPUT CURRENT LIMIT
vs. PROGRAMMED OUTPUT VOLTAGE
INPUT CURRENT LIMIT
vs. PROGRAMMED VALUE
ILIM = 500mA
570
560
550
540
530
520
10,000
1000
VOUT = 5V
INPUT CURRENT LIMIT (mA)
580
MAX8834Y/Z toc29
OUTPUT CURRENT (mA)
MAX8834Y/Z toc30
OUTPUT VOLTAGE (V)
5.02
MAX8834Y/Z toc27
5.02
INPUT CURRENT LIMIT (mA)
MAX8834Y/MAX8834Z
Adaptive Step-Up Converters
with 1.5A Flash Driver
800
600
IDEAL LINE
400
200
510
0
500
3.7
4.0
4.3
4.6
4.9
PROGRAMMED OUTPUT VOLTAGE (V)
10
5.2
0
200
400
600
PROGRAMMED VALUE (mA)
______________________________________________________________________________________
800
Adaptive Step-Up Converters
with 1.5A Flash Driver
PIN
NAME
FUNCTION
A1, B1
OUT
Regulator Output. Connect OUT to the anodes of the external LEDs. Bypass OUT to PGND with a 10μF
ceramic capacitor. OUT is connected to LX through an internal 10k resistor during shutdown.
A2, B2
LX
Inductor Connection. Connect LX to the switched side of the inductor. LX is internally connected to
the drains of the internal MOSFETs. LX is connected to OUT through an internal 10k resistor during
shutdown.
A3, B3
PGND
Power Ground. Connect PGND to AGND and to the input capacitor ground. Connect PGND to the PCB
ground plane.
A4
IN
Analog Supply Voltage Input. The input voltage range is 2.5V to 5.5V. Bypass IN to AGND and PGND
with a 10μF ceramic capacitor as close as possible to the IC. IN is high impedance during shutdown.
A5
VDD
Logic Input Supply Voltage. Connect VDD to the logic supply driving SCL, SDA, LED_EN, and GSMB.
Bypass VDD to AGND with a 0.1μF ceramic capacitor. When VDD is below the UVLO, the I2C registers
reset and the step-up converter turns off.
B4
SCL
I2C Clock Input. Data is read on the rising edge of SCL.
B5
AGND
Analog Ground. Connect AGND to PGND and to the input capacitor ground. Connect AGND to the PCB
ground plane.
C1
COMP
Compensation Input. See the Compensation Network Selection section for details. COMP is internally
pulled to AGND through a 180 resistor in shutdown.
C2, D2
FGND
FLED1/FLED2 and INDLED Power Ground. Connect FGND to PGND.
C3
LED_EN
LED Enable Logic Input. LED_EN controls FLED1, FLED2, and INDLED, depending on control bits
written into the LED_CNTL register. See the LED_EN Control register description for an explanation of
this input function. LED_EN has an internal 800k pulldown resistor to AGND.
C4
GSMB
GSM Blank Signal. Assert GSMB to reduce the current regulator settings according to the values
programmed into the GSMB_CUR register. The status of the flash safety timer and the flash/movie
mode values in the current regulator registers are not affected by the GSMB state. Connect GSMB to
the PA module enable signal or other suitable logic signal that indicates a GSM transmit is in
process. Polarity of this signal is set by a bit in the GSMB_CUR register (default is active-high).
GSMB has an internal 800k pulldown resistor to AGND.
C5
SDA
I2C Data Input. Data is read on the rising edge of SCL and data is clocked out on the falling edge of
SCL.
D1
FLED2
FLED2 Current Regulator. Current flowing into FLED2 is based on the internal I2C registers
FLASH2_CUR and MOVIE_CUR. Connect FLED2 to the cathode of an external flash LED or LED
module. FLED2 is high impedance during shutdown. If unused, connect FLED2 to ground.
D3
FLED1
FLED1 Current Regulator. Current flowing into FLED1 is based on the internal I2C registers
FLASH1_CUR and MOVIE_CUR. Connect FLED1 to the cathode of an external flash LED or LED
module. FLED1 is high impedance during shutdown. If unused, connect FLED1 to ground.
D4
INDLED
D5
NTC
INDLED Current Regulator. Current flowing into INDLED is based on the internal I2C registers
IND_CUR. Connect INDLED to the cathode of an external indicator LED. INDLED is high impedance
during shutdown. If unused, connect INDLED to ground.
NTC Bias Output. NTC provides 20μA to bias the NTC thermistor. The NTC voltage is compared to the
trip threshold programmed by the NTC_CNTL register. NTC is high impedance during shutdown.
Connect NTC to IN if not used. See the Finger-Burn Protection (NTC) section for details.
______________________________________________________________________________________
11
MAX8834Y/MAX8834Z
Pin Description
MAX8834Y/MAX8834Z
Adaptive Step-Up Converters
with 1.5A Flash Driver
Detailed Description
The MAX8834Y/MAX8834Z flash drivers integrate an
adaptive 1.5A PWM step-up DC-DC converter, two
750mA white LED camera flash/movie current regulators, and a 16mA indicator LED current regulator. An
I2C interface controls individual output on/off, the stepup output voltage setting, the movie/flash current, and
the flash timer duration settings.
Step-Up Converter (LX, OUT, COMP, PGND)
The MAX8834Y/MAX8834Z include a fixed-frequency,
PWM step-up converter that supplies power to the flash
LEDs. The output voltage is programmable from 3.7V to
5.2V (in 100mV steps) through the I2C interface. The
output voltage can also be set adaptively based on the
LED forward voltage. The step-up converter switches
an internal power MOSFET and synchronous rectifier at
a constant 2MHz or 4MHz frequency, with varying duty
cycle up to 75%, to maintain constant output voltage as
the input voltage and load vary. Internal circuitry prevents any unwanted subharmonic switching by forcing
a minimum 7% (typ) duty cycle.
When the step-up converter is set to dropout mode, the
internal synchronous rectifier is driven fully on, keeping
the voltage at OUT equal to the LX input. This mode
provides the lowest current consumption when driving
LEDs with low forward voltage.
The output voltage is internally monitored for a fault
condition. If the output voltage drops below 8% (typ) of
the nominal programmed value, a POK fault is indicated in STATUS1 register bit 5. This feature is disabled if
the step-up converter is set to operate in adaptive
mode.
Overvoltage Protection
The MAX8834Y/MAX8834Z include a comparator to
monitor the output voltage (V OUT ) during adaptive
mode operation of the step-up converter. If at anytime
the output voltage exceeds a maximum threshold of
5.5V, the COMP capacitor is discharged until the output
voltage is reduced by the 200mV (typ) hysteresis. Once
the output voltage drops below this threshold, normal
charging of the COMP capacitor is resumed.
Flash Current Regulator
(FLED1 and FLED2)
A low-dropout linear current regulator from FLED1/
FLED2 to FGND sinks current from the cathode terminal
of the flash LED(s). The FLED1/FLED2 current is regulated to I2C programmable levels for movie mode (up to
125mA, see Table 5) and flash mode (up to 750mA,
12
see Tables 3 and 4). The movie mode provides continuous lighting when enabled through I 2C or LED_EN.
When the flash mode is enabled, a flash safety timer,
programmable from 50ms to 800ms through I2C, limits
the duration of the flash mode. Once the flash safety
timer expires, the current regulators return to movie
mode if movie mode was active when a flash event was
triggered. The flash mode has priority over the movie
mode.
Flash Safety Timer
The flash safety timer is activated any time flash mode is
selected, either with LED_EN or through the I2C interface.
The flash safety timer, programmable from 50ms to
800ms through I2C, limits the duration of the flash mode
in case LED_EN is stuck high or the I2C command to
turn off has not been sent within the programmed flash
safety timer duration. This timer can be configured to
operate either in one-shot mode or maximum flash
duration mode (see Table 9). In one-shot mode, the
flash function is initiated on the rising edge of LED_EN
(or I2C bit) and terminated based on the programmed
value of the safety timer (see Figure 1). In the maximum
flash timer mode, flash function remains enabled as
long as LED_EN (or I2C bit) is high, unless the preprogrammed safety timer times out (see Figure 2).
Once the flash mode is disabled, by either LED_EN,
I2C, or flash safety timer, the flash has to be off for a
minimum time (flash safety timer reset inhibit period),
before it can be reinitiated (see Figure 3). This prevents
spurious events from re-enabling the flash mode.
Indicator Current Regulator (INDLED)
A low-dropout linear current regulator from INDLED to
FGND sinks current from the cathode terminal of the
indicator LED. The INDLED current is regulated to I2C
programmable levels up to 16mA. Programmable control is provided for ramp-up (OFF to ON) and rampdown (ON to OFF) times, as well as blink rate and duty
cycle. The user can choose to enable or disable the
ramp time and blink rate features. See Tables 6, 7, and
8 for more information.
INDLED Blink Function
INDLED current regulator is able to generate a blink
function. The OFF and ON time for INDLED are set
using the I2C interface. See Figure 4.
INDLED Ramp Function
The INDLED current regulator output provides ramp-up/
down for smooth transition between different brightness
settings. The ramp-up/down times are controlled by the
______________________________________________________________________________________
Adaptive Step-Up Converters
with 1.5A Flash Driver
MAX8834Y/MAX8834Z
ENABLING OF FLASH MODE BY
LED_EN OR I2C CONTROL
ONE-SHOT FLASH TIMER
ONE-SHOT FLASH TIMER
Figure 1. One-Shot Flash-Timer Mode
ENABLING OF FLASH MODE BY
LED_EN OR I2C CONTROL
MAXIMUM FLASH
SAFETY TIMER
MAXIMUM FLASH TIMER
Figure 2. Maximum Flash-Timer Mode
ENABLING OF FLASH MODE BY
LED_EN OR I2C CONTROL
30ms
Figure 3. Flash Safety Timer Reset Inhibit Period
IIND[4:0]
tIND_OFF
tIND_ON
Figure 4. Blink Function Timing
IND_RU and IND_RD control bits, and the ramp function is enabled/disabled by the IND_RP_EN bit. The
current regulator increases/decreases the current onestep every tRAMP/32 until 0mA or IND[4:0] current is
reached. See Figures 5 and 6.
Combining BLINK Timer and Ramp Function
When using the ramp function for INDLED together with
the blink timer, keep the ramp-up timer shorter than the
ON blink timer and the ramp-down timer shorter than
the OFF timer. Failing to comply with this results in the
______________________________________________________________________________________
13
MAX8834Y/MAX8834Z
Adaptive Step-Up Converters
with 1.5A Flash Driver
128ms
IINDLED = FULL SCALE
256ms
512ms
1024ms
IINDLED = 1/2 SCALE
0mA
Figure 5. Ramp-Up Behavior
IINDLED = FULL SCALE
IINDLED = 1/2 SCALE
0mA
128ms
256ms
512ms
1024ms
Figure 6. Ramp-Down Behavior
tIND_OFF
tIND_ON
tIND_OFF
tIND_ON
tIND_OFF
IIND_LED = IND_LED[4:0]
IIND_LED = CODE 0111
IIND_LED = CODE 0011
IIND_LED = OFF
t=
tIND_RU
32
t=
tIND_RD
32
Figure 7. Combining RAMP Function and Blink Timer
programmed current not being reached during the ON
time, or the INDLED current not returning to 0mA during
the OFF time. See Figure 7.
tIND _ ON ≥
tIND _ RU
tIND _ OFF ≥
32
(IND _ LED + 1)
tIND _ RD
32
(IND _ LED + 1)
where IND_LED is the code from 0 to 31 specified in
the IND_LED[4:0].
LED Enable Input (LED_EN)
The LED_EN logic input can enable/disable the FLED1,
FLED2, and INDLED current regulators. It can be
programmed to control movie mode, flash mode, and
indicator mode by using the IND_EN, MOVIE_EN,
and FLASH_EN bits, respectively. See Table 8 for
more information.
14
If FLED1/FLED2 is enabled for both movie and flash
modes at the same time, flash mode has priority. Once
the safety timer expires, the current regulator then
returns to the movie mode.
Watchdog Timer
The MAX8834Y/MAX8834Z include a watchdog timer
function that can be programmed using the I2C interface from 4 seconds to 16 seconds with a 4-second
step. If the watchdog timer expires, the MAX8834Y/
MAX8834Z interpret it as an indication that the system
is no longer responding and enters safe mode. In safe
mode, the MAX8834Y/MAX8834Z disable all current
regulators and the step-up DC-DC converter to prevent
potential damage to the system. The I2C setting for the
respective registers does not change, therefore, resetting the watchdog timer reverts the MAX8834Y/
MAX8834Z back to the state present before entering
safe mode.
______________________________________________________________________________________
Adaptive Step-Up Converters
with 1.5A Flash Driver
WATCHDOG
TIMER RESET
WATCHDOG
TIMER RESET
MAX8834Y/MAX8834Z
WATCHDOG
TIMER ENABLED
WATCHDOG
TIMEOUT
SUSPENDING ALL
CURRENT
REGULATIONS
WATCHDOG
TIMER RESET
WDT_RST IS
CLEARED
(I2C) WDT_EN
(I2C) WDT_RST
WATCHDOG TIMER
LED_EN
IFLED_ OR
IINDLED
t < WDT_DUR[1:0]
t < WDT_DUR[1:0]
t < WDT_DUR[1:0]
t > WDT_DUR[1:0]
Figure 8. Watchdog Timer Timing Diagram 1
WATCHDOG
TIMER ENABLED
WATCHDOG
TIMER RESET
WATCHDOG
TIMEOUT
SUSPENDING ALL
CURRENT
REGULATIONS
WATCHDOG
TIMER RESET
WATCHDOG
TIMER RESET
WDT_RST IS
CLEARED
(I2C) WDT_EN
(I2C) WDT_RST
WATCHDOG TIMER
LED_EN
IFLED_ OR
IINDLED
t < WDT_DUR[1:0]
t < WDT_DUR[1:0]
t > WDT_DUR[1:0]
t < WDT_DUR[1:0]
Figure 9. Watchdog Timer Timing Diagram 2
Setting the WDT_EN bit to 1 in the TMR_DUR register
(Table 9) enables the watchdog timer. Resetting the
watchdog timer is achieved by the rising or falling edge
of LED_EN or by setting bit 0 in the WDT_RST register
(Table 14). See Figures 8 and 9 for two examples of
watchdog timer timing diagrams.
______________________________________________________________________________________
15
MAX8834Y/MAX8834Z
Adaptive Step-Up Converters
with 1.5A Flash Driver
GSMB EVENT
GSMB (ACTIVE-HIGH)
INPUT CURRENT
PREDEFINED INPUT CURRENT
LIMIT DURING GSMB
FLED1/FLED2 DECREASED ONE
LSB SINCE IIN > ILIM[3:0]
FLED1/FLED2 INCREASED
ONE LSB SINCE IIN < ILIM[3:0]
FLED2 OUTPUT
CURRENT
FLED1 OUTPUT
CURRENT
FLASH1_CUR
SETTING
TIME
HC_TMR[1:0]
1μs AFTER GSMB
ACTIVATED, FLED_ GOES
TO THE MINIMUM SETTING
1μs AFTER GSMB
DEACTIVATED, FLED_ GOES
TO THE PREVIOUS SETTING
Figure 10. Input Current Limit During GSMB Event
GSM Blank Function (GSMB)
The GSMB input is provided to allow the flash current to
be momentarily reduced during a GSM transmit to
reduce the peak current drawn from the battery. The
input current limit ensures that the maximum possible
output current is always provided, regardless of the
input voltage and the LED forward voltages.
When a GSMB event is triggered, the FLED1 and
FLED2 current regulators go to the lowest setting to
ensure the current drawn from the battery is quickly
reduced to a safe level. The MAX8834Y/MAX8834Z
16
then start increasing the FLED1 and FLED2 current by
one LSB steps, at a time interval set by HC_TMR[1:0]
(see Table 11). The increasing continues until either the
predefined FLED1/FLED2 current setting is reached or
the input current exceeds the maximum predefined
input current limit during a GSMB event. When the input
current exceeds the predefined input current limit, the
FLED1/FLED2 current is reduced by one LSB. The
MAX8834Y/MAX8834Z continue to adjust the FLED1
and FLED2 up and down depending on the input current limit as long as the GSMB event is present. See
Figure 10 for more detailed information.
______________________________________________________________________________________
Adaptive Step-Up Converters
with 1.5A Flash Driver
Finger-Burn Protection (NTC)
An NTC input is provided for the (optional) finger-burn
protection feature. To use this feature, connect a 100kΩ
NTC with B = 4550 between NTC and AGND. NTC
sources 20µA current and the voltage established by
this current and the NTC resistance is compared internally to a voltage threshold in the range of 200mV to
550mV, programmed through bits [2:0] of the NTC
Control register (see Table 10).
If the voltage on the NTC pin falls below the programmed
threshold during a flash event, the flash cycle is immediately terminated, and an indication is latched through bit 3
in the STATUS1 register (see Table 15).
To disable this function, clear bit 3 (enable bit) in the
NTC Control register.
MAXFLASH Function
During high load currents, the battery voltage momentarily drops due to its internal ESR, together with the
serial impedance from the battery to the load. For
equipment requiring a minimum voltage for stable operation, the battery ESR needs to be calculated to estimate the maximum battery current that maintains the
battery voltage above the critical threshold. Due to the
complicated measurement of the battery ESR, the
MAX8834Y/MAX8834Z feature the MAXFLASH function
to prevent the battery voltage from dropping below the
threshold voltage. See Figure 11 for details.
The MAX8834Y/MAX8834Z input voltage is monitored
during a FLASH/MOVIE event. If the input voltage
drops below a predefined threshold (VLB_TH), it indicates that the FLASH/MOVIE event is drawing more
current than the battery can support. As a result, the
FLED1/FLED2 current regulators start decreasing their
output currents by one step. Therefore, the input current is reduced and the input voltage starts to rise due
to the internal battery ESR. The input voltage is then
sampled again after tLB_TMR and compared to VLB_TH
plus a predefined hysteresis (V LB_HYS ). If it is still
below VLB_TH + VLB_HYS, the FLED1/FLED2 current
regulators reduce their output current again to ensure
that minimum input voltage is available for the system.
If the input voltage is above VLB_TH + VLB_HYS, the current regulator increases the output current by one step
(if it is less than the user-defined output current). To
disable the hysteresis, set LB_HYS[1:0] to 11. In this
case, after the FLED1/FLED2 current is reduced, it
stays at the current setting. Figures 12, 13, and 14
show examples of MAXFLASH function operation. See
Tables 12 and 13 for control register details.
The MAXFLASH function continues for the entire duration of the FLASH/MOVIE event to ensure that the
FLASH/MOVIE output current is always maximized for
the specific operating conditions.
Undervoltage Lockout
The MAX8834Y/MAX8834Z contain undervoltage lockout (UVLO) circuitry that disables the IC until VIN is
greater than 2.3V (typ). Once V IN rises above 2.3V
(typ), the UVLO circuitry does not disable the IC until
VIN falls below the UVLO threshold minus the hysteresis
voltage. The MAX8834Y/MAX8834Z also contain a VDD
UVLO circuitry that monitors the VDD voltage. When the
VDD voltage falls below 1.4V (typ), the contents of all
the logic registers are reset to their default states. The
logic registers are only reset in a VDD UVLO condition
and not an IN UVLO condition.
tLB_TMR
IN
IOUT_MAX
DOWN
VLB_TH
CURRENT
REGULATOR
UP
VLB_HYS
VLB_TH
Figure 11. Block Diagram of MAXFLASH Function
______________________________________________________________________________________
17
MAX8834Y/MAX8834Z
To use this feature, connect the logic signal used to
enable the PA, or equivalent, to the GSMB input.
Assertion of this signal does not change the current status of the flash safety timer or the flash current values
stored in the I2C registers. Once the signal is deasserted, the current regulators change back to their previously programmed values. Polarity of this signal is
controlled through bit 6 in the GSMB_CUR register
(Table 11). The default is active-high.
FLASH/MOVIE CURRENT
BATTERY VOLTAGE
VLB_TH + VLB_HYS
VLB_TH
tLB_TMR
TIME
Figure 12. Example 1 of MAXFLASH Function Operation
VLB_TH
IMAX
FLASH/MOVIE CURRENT
VLB_TH + VLB_HYS
BATTERY VOLTAGE
REDUCTION IN BATTERY CURRENT CAUSED
BY OTHER SYSTEM
tLB_TMR
TIME
Figure 13. Example 2 of MAXFLASH Function Operation
VLB_TH + VLB_HYS
VLB_TH
FLASH CURRENT IS NOT INCREASED
AGAIN SINCE LB_HYS = 11
IMAX
tLB_TMR
TIME
Figure 14. Example 3 of MAXFLASH Function Operation with Hysteresis Disabled
18
______________________________________________________________________________________
FLASH/MOVIE CURRENT
REDUCTION IN BATTERY CURRENT
CAUSED BY OTHER SYSTEM
BATTERY VOLTAGE
MAX8834Y/MAX8834Z
Adaptive Step-Up Converters
with 1.5A Flash Driver
Adaptive Step-Up Converters
with 1.5A Flash Driver
Open/Short Detection
The MAX8834Y/MAX8834Z monitor the FLED1, FLED2,
and INDLED voltage to detect any open or short LEDs.
A short fault is detected when the voltage rises above
VOUT - 1V (typ), and an open fault is detected when
the voltage falls below 100mV. The fault detection circuitry is only activated when the corresponding current
regulator is enabled and provides a continuous monitor of the current regulator condition. Once a fault is
detected, the corresponding current regulator is disabled and the status is latched into the corresponding
fault register bit (see Table 15). This allows the processor to determine the MAX8834Y/MAX8834Z operating
condition.
Shutdown and Standby
The MAX8834Y/MAX8834Z are in shutdown when either
VIN or VDD are in UVLO. In shutdown, supply current is
reduced to 0.1µA (typ). When VIN is above its UVLO
threshold, but VDD is below its UVLO threshold, the IC
disables its internal reference, keeps all registers reset,
turns the step-up converter off, and turns the
FLED1/FLED2 current regulators off (high impedance).
Once a logic-level voltage is supplied to VDD, the IC
enters standby condition and is ready to accept I2C
commands. The internal MOSFET, synchronous rectifier, and FLED1/FLED2 are also high impedance in
standby.
Thermal Shutdown
Thermal shutdown limits total power dissipation in the
MAX8834Y/MAX8834Z. When the junction temperature
exceeds +160°C (typ), the IC turns off, allowing itself to
cool. The IC turns on and begins soft-start after the junction temperature cools by 20°C. This results in a pulsed
output during continuous thermal overload conditions.
I2C Serial Interface
An I2C-compatible, 2-wire serial interface controls the
step-up converter output voltage, flash, movie, and
indicator current settings, flash duration, and other
parameters. The serial bus consists of a bidirectional
serial-data line (SDA) and a serial-clock input (SCL).
The MAX8834Y/MAX8834Z are slave-only devices, relying upon a master to generate a clock signal. The master initiates data transfer to and from the MAX8834Y/
Typical shutdown timing characteristics are shown in
the Typical Operating Characteristics.
Parallel Connection of Current Regulators
The FLED1/FLED2 current regulators can be connected
in parallel as long as the system software properly sets
the current levels for each regulator. Unused current
regulators may be connected to ground. The FLED1/
SDA
tSU,STA
tSU,DAT
tLOW
tBUF
tHD,STA
tSU,STO
tHD,DAT
tHIGH
SCL
tHD,STA
tR
tF
START CONDITION
REPEATED START CONDITION
STOP
CONDITION
START
CONDITION
Figure 15. 2-Wire Serial Interface Timing Detail
______________________________________________________________________________________
19
MAX8834Y/MAX8834Z
FLED2 regulators must be disabled through I 2 C to
avoid a fault detection from an open or short.
Soft-Start
The step-up converter implements a soft-start to control
inrush current when it turns on. It soft-starts by charging
CCOMP with a 100µA current source. During this time,
the internal MOSFET is switching at the minimum duty
cycle. Once V COMP rises above 1V, the duty cycle
increases until the output voltage reaches the desired
regulation level. COMP is pulled to AGND with a 180Ω
(typ) internal resistor during IN, UVLO, dropout mode,
or shutdown. See the Typical Operating Characteristics
for an example of soft-start operation. Soft-start is reinitiated after UVLO or if the step-up converter is reenabled after shutdown or dropout mode.
MAX8834Y/MAX8834Z
Adaptive Step-Up Converters
with 1.5A Flash Driver
SCL
SDA
START
CONDITION
(S)
DATA LINE STABLE
DATA VALID
DATA ALLOWED TO
CHANGE
STOP
CONDITION
(P)
Figure 16. Bit Transfer
MAX8834Z and generates SCL to synchronize the data
transfer (Figure 15).
I2C is an open-drain bus. Both SDA and SCL are bidirectional lines, connected to a positive supply voltage
through a pullup resistor. They both have Schmitt triggers and filter circuits to suppress noise spikes on the
bus to assure proper device operation.
A bus master initiates communication with the
MAX8834Y/MAX8834Z as a slave device by issuing a
START (S) condition followed by the MAX8834Y/
MAX8834Z address. The MAX8834Y/MAX8834Z
address byte consists of 7 address bits and a read/
write bit (R/W). After receiving the proper address, the
MAX8834Y/MAX8834Z issue an acknowledge bit by
pulling SDA low during the ninth clock cycle.
Slave Address
The MAX8834Y/MAX8834Z act as a slave transmitter/
receiver. Its slave address is 0x94 for write operations
and 0x95 for read operations.
Bit Transfer
Each data bit, from the most significant bit to the least
significant bit, is transferred one by one during each
clock cycle. During data transfer, the SDA signal is
allowed to change only during the low period of the
SCL clock and it must remain stable during the high
period of the SCL clock (Figure 16).
20
START and STOP Conditions
Both SCL and SDA remain high when the bus is not
busy. The master signals the beginning of a transmission with a START (S) condition by transitioning SDA
from high to low while SCL is high. When the master
has finished communicating with the MAX8834Y/
MAX8834Z, it issues a STOP (P) condition by transitioning SDA from low to high while SCL is high. The bus is
then free for another transmission (Figure 17). Both
START and STOP conditions are generated by the bus
master.
Acknowledge
The acknowledge bit is used by the recipient to handshake the receipt of each byte of data (Figure 18). After
data transfer, the master generates the acknowledge
clock pulse and the recipient pulls down the SDA line
during this acknowledge clock pulse so the SDA line
stays low during the high duration of the clock pulse.
When the master transmits the data to the
MAX8834Y/MAX8834Z, it releases the SDA line and the
MAX8834Y/MAX8834Z take control of the SDA line and
generate the acknowledge bit. When SDA remains high
during this 9th clock pulse, this is defined as the not
acknowledge signal. The master can then generate
either a STOP condition to abort the transfer, or a
repeated START condition to start a new transfer.
______________________________________________________________________________________
Adaptive Step-Up Converters
with 1.5A Flash Driver
D7
D6
D0
SDA
NOT ACKNOWLEDGE
SDA BY SLAVE
ACKNOWLEDGE
SCL
SCL
1
START
CONDITION
STOP
CONDITION
START CONDITION
2
8
9
CLOCK PULSE FOR
ACKNOWLEDGEMENT
Figure 17. START and STOP Conditions
Figure 18. Acknowledge
Write Operations
The MAX8834Y/MAX8834Z recognize the write byte
protocol as defined in the SMBus™ specification and
shown in section A of Figure 19. The write byte protocol allows the I2C master device to send 1 byte of data
to the slave device. The write-byte protocol requires a
register pointer address for the subsequent write. The
MAX8834Y/MAX8834Z acknowledge any register
pointer even though only a subset of those registers
actually exists in the device. The write byte protocol is
as follows:
1) The master sends a start command.
Use the following procedure to write to a sequential
block of registers:
1) The master sends a start command.
2) The master sends the 7-bit slave address followed
by a write bit.
2) The master sends the 7-bit slave address followed
by a write bit.
3) The addressed slave asserts an acknowledge by
pulling SDA low.
4) The master sends the 8-bit register pointer of the
first register to write.
5) The slave acknowledges the register pointer.
6) The master sends a data byte.
7) The slave updates with the new data.
3) The addressed slave asserts an acknowledge by
pulling SDA low.
4) The master sends an 8-bit register pointer.
5) The slave acknowledges the register pointer.
6) The master sends a data byte.
8) The slave acknowledges the data byte.
9) Steps 6 to 8 are repeated for as many registers in
the block, with the register pointer automatically
incremented each time.
10) The master sends a STOP condition.
7) The slave updates with the new data.
8) The slave acknowledges the data byte.
9) The master sends a STOP (P) condition.
In addition to the write-byte protocol, the MAX8834Y/
MAX8834Z can write to multiple registers as shown in
section B of Figure 19. This protocol allows the I2C
master device to address the slave only once and then
send data to a sequential block of registers starting at
the specified register pointer.
Read Operations
The method for reading a single register (byte) is shown
in section A of Figure 20. To read a single register:
1) The master sends a start command.
2) The master sends the 7-bit slave address followed
by a write bit.
3) The addressed slave asserts an acknowledge by
pulling SDA low.
4) The master sends an 8-bit register pointer.
SMBus is a trademark of Intel Corp.
______________________________________________________________________________________
21
MAX8834Y/MAX8834Z
SDA BY MASTER
MAX8834Y/MAX8834Z
Adaptive Step-Up Converters
with 1.5A Flash Driver
LEGEND
MASTER TO
SLAVE
SLAVE TO
MASTER
A. WRITING TO A SINGLE REGISTER WITH THE WRITE BYTE PROTOCOL
1
S
7
SLAVE ADDRESS
1
1
8
1
8
1
1
NUMBER OF BITS
0
A
REGISTER POINTER
A
DATA
A
P
8
1
8
1
A
DATA X+1
A
R/W
B. WRITING TO MULTIPLE REGISTERS
1
7
1
1
8
1
S
SLAVE ADDRESS
0
A
REGISTER POINTER X
A
8
1
8
DATA X+n-1
A
DATA X+n
DATA X
NUMBER OF BITS
...
R/W
...
1
NUMBER OF BITS
A P
Figure 19. Writing to the MAX8834Y/MAX8834Z
5) The slave acknowledges the register pointer.
6) The master sends a REPEATED START (Sr) condition.
7) The master sends the 7-bit slave address followed
by a read bit.
8) The slave asserts an acknowledge by pulling SDA
low.
9) The slave sends the 8-bit data (contents of the register).
10) The master asserts an acknowledge by pulling SDA
low.
11) The master sends a STOP (P) condition.
In addition, the MAX8834Y/MAX8834Z can read a block
of multiple sequential registers as shown in section B of
Figure 20. Use the following procedure to read a
sequential block of registers:
1) The master sends a start command.
2) The master sends the 7-bit slave address followed
by a write bit.
22
3) The addressed slave asserts an acknowledge by
pulling SDA low.
4) The master sends an 8-bit register pointer of the
first register in the block.
5) The slave acknowledges the register pointer.
6) The master sends a REPEATED START condition.
7) The master sends the 7-bit slave address followed
by a read bit.
8) The slave asserts an acknowledge by pulling SDA
low.
9) The slave sends the 8-bit data (contents of the register).
10) The master asserts an acknowledge by pulling SDA
low.
11) Steps 9 and 10 are repeated for as many registers
in the block, with the register pointer automatically
incremented each time.
12) The master sends a STOP condition.
______________________________________________________________________________________
Adaptive Step-Up Converters
with 1.5A Flash Driver
MASTER TO
SLAVE
SLAVE TO
MASTER
A. READING A SINGLE REGISTER
1
S
7
SLAVE ADDRESS
1
1
8
1
0
A
REGISTER POINTER
1
1
8
1
A Sr
8
1
1
8
1
1
SLAVE ADDRESS
1
A
DATA
A
P
NUMBER OF BITS
R/W
B. READING MULTIPLE REGISTERS
1
S
7
SLAVE ADDRESS
0
1
REGISTER POINTER X
A
A
1
8
Sr
1
SLAVE ADDRESS
R/W
8
DATA X+1
A
NUMBER OF BITS
1
A
...
R/W
8
...
1 1
DATA X+1
1
A ...
8
DATA X+n-1
1
8
A
DATA X+n
1
1
NUMBER OF BITS
A P
Figure 20. Reading from the MAX8834Y/MAX8834Z
______________________________________________________________________________________
23
MAX8834Y/MAX8834Z
LEGEND
MAX8834Y/MAX8834Z
Adaptive Step-Up Converters
with 1.5A Flash Driver
Table 1. Register Map
TABLE
REGISTER
ADDRESS (hex)
TYPE
BOOST_CNTL
Table 2
00
R/W
Step-up converter control
FLASH1_CUR
Table 3
01
R/W
FLED1 flash current control
FLASH2_CUR
Table 4
02
R/W
FLED2 flash current control
MOVIE_CUR
Table 5
03
R/W
FLED1 and FLED2 movie current control
—
04
R/W
Reserved for future use
Table 6
05
R/W
Indicator LED current control
NAME
Reserved for future use
IND_CUR
Reserved for future use
DESCRIPTION
—
06
R/W
Reserved for future use
Table 7
07
R/W
Indicator LED ramp and blink control
—
08
R/W
Reserved for future use
LED_CNTL
Table 8
09
R/W
FLED1, FLED2, and INDLED on/off and mode control,
and definition of LED_EN logic input function
TMR_DUR
Table 9
0A
R/W
Watchdog timer and flash safety timer control
NTC_CNTL
Table 10
0B
R/W
NTC function control
GSMB_CUR
Table 11
0C
R/W
FLED1 and FLED2 current control during GSM transmit
MAXFLASH1
Table 12
0D
R/W
MAXFLASH function register 1
MAXFLASH2
Table 13
0E
R/W
MAXFLASH function register 2
WDT_RST
Table 14
16
R/W
Watchdog timer reset
STATUS1
Table 15
17
R
STATUS2
Table 16
18
R
—
19
R/W
CHIP_ID1
Table 17
1A
R
Die type information
CHIP_ID2
Table 18
1B
R
Die type and mask revision information
IND_CNTL
Reserved for future use
Reserved for future use
24
Status register
Status register
Reserved for future use
______________________________________________________________________________________
Adaptive Step-Up Converters
with 1.5A Flash Driver
This register contains step-up converter control values.
REGISTER NAME
BOOST_CNTL
Address
0x00
Reset Value
0x00
Type
Read/write
Special Features
—
BIT
NAME
B7 (MSB)
—
Reserved for future use
0
B6
BOOST_EN
0 = Step-up converter off
1 = Step-up converter on
0
00 = Step-up voltage set adaptively
01 = Step-up voltage set programmatically according to
BOOST_CNTL[3:0]
10 = Step-up converter runs in dropout
11 = Step-up converter automatically changes between adaptive
regulation and dropout mode depending on operating conditions
00
B5
BOOST_MODE
B4
B3
B2
BOOST_CNTL[3:0]
B1
B0 (LSB)
DESCRIPTION
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
3.7V
3.8V
3.9V
4.0V
4.1V
4.2V
4.3V
4.4V
4.5V
4.6V
4.7V
4.8V
4.9V
5.0V
5.1V
5.2V
DEFAULT VALUE
0000
______________________________________________________________________________________
25
MAX8834Y/MAX8834Z
Table 2. BOOST_CNTL
MAX8834Y/MAX8834Z
Adaptive Step-Up Converters
with 1.5A Flash Driver
Table 3. FLASH1_CUR
This register contains FLED1 flash current control values.
REGISTER NAME
FLASH1_CUR
Address
0x01
Reset Value
0x00
Type
Read/write
Special Features
BIT
—
NAME
B7 (MSB)
B6
B5
FLASH1[4:0]
B4
B3
26
DESCRIPTION
FLED1 Flash Mode Current Setting
00000 = 23.44mA
00001 = 46.88mA
00010 = 70.32mA
00011 = 93.76mA
00100 = 117.20mA
00101 = 140.64mA
00110 = 164.08mA
00111 = 187.52mA
01000 = 210.96mA
01001 = 234.40mA
01010 = 257.84mA
01011 = 281.28mA
01100 = 304.72mA
01101 = 328.16mA
01110 = 351.60mA
01111 = 375.04mA
10000 = 398.48mA
10001 = 421.92mA
10010 = 445.36mA
10011 = 468.80mA
10100 = 492.24mA
10101 = 515.68mA
10110 = 539.12mA
10111 = 562.56mA
11000 = 586.00mA
11001 = 609.44mA
11010 = 632.88mA
11011 = 656.32mA
11100 = 679.76mA
11101 = 703.20mA
11110 = 726.56mA
11111 = 750.00mA
DEFAULT VALUE
00000
B2
—
Reserved for future use
B1
—
Reserved for future use
—
B0 (LSB)
—
Reserved for future use
—
______________________________________________________________________________________
—
Adaptive Step-Up Converters
with 1.5A Flash Driver
MAX8834Y/MAX8834Z
Table 4. FLASH2_CUR
This register contains FLED2 flash current control values.
REGISTER NAME
FLASH2_CUR
Address
0x02
Reset Value
0x00
Type
Read/write
Special Features
BIT
—
NAME
B7 (MSB)
B6
B5
FLASH2[4:0]
B4
B3
DESCRIPTION
FLED2 Flash Mode Current Setting
00000 = 23.44mA
00001 = 46.88mA
00010 = 70.32mA
00011 = 93.76mA
00100 = 117.20mA
00101 = 140.64mA
00110 = 164.08mA
00111 = 187.52mA
01000 = 210.96mA
01001 = 234.40mA
01010 = 257.84mA
01011 = 281.28mA
01100 = 304.72mA
01101 = 328.16mA
01110 = 351.60mA
01111 = 375.04mA
10000 = 398.48mA
10001 = 421.92mA
10010 = 445.36mA
10011 = 468.80mA
10100 = 492.24mA
10101 = 515.68mA
10110 = 539.12mA
10111 = 562.56mA
11000 = 586.00mA
11001 = 609.44mA
11010 = 632.88mA
11011 = 656.32mA
11100 = 679.76mA
11101 = 703.20mA
11110 = 726.56mA
11111 = 750.00mA
DEFAULT VALUE
00000
B2
—
Reserved for future use
B1
—
Reserved for future use
—
—
B0 (LSB)
—
Reserved for future use
—
______________________________________________________________________________________
27
MAX8834Y/MAX8834Z
Adaptive Step-Up Converters
with 1.5A Flash Driver
Table 5. MOVIE_CUR
This register contains FLED1 and FLED2 movie current control values.
REGISTER NAME
MOVIE_CUR
Address
0x03
Reset Value
0x00
Type
Read/write
Special Features
—
BIT
NAME
B7 (MSB)
—
B6
B5
MOVIE1[2:0]
B4
B3
—
B2
B1
B0 (LSB)
28
MOVIE2[2:0]
DESCRIPTION
Reserved for future use
FLED1 Movie Mode Current Setting
000 = 15.625mA
001 = 31.250mA
010 = 49.875mA
011 = 62.500mA
100 = 78.125mA
101 = 93.750mA
110 = 109.375mA
111 = 125.000mA
Reserved for future use
FLED2 Movie Mode Current Setting
000 = 15.625mA
001 = 31.250mA
010 = 49.875mA
011 = 62.500mA
100 = 78.125mA
101 = 93.750mA
110 = 109.375mA
111 = 125.000mA
______________________________________________________________________________________
DEFAULT NAME
—
000
—
000
Adaptive Step-Up Converters
with 1.5A Flash Driver
This register contains indicator LED current control values.
REGISTER NAME
Address
IND_CUR
0x05
Reset Value
0x00
Type
Read/write
Special Features
—
BIT
NAME
B7 (MSB)
—
DESCRIPTION
0
0
0
B6
IND_BL_EN
INDLED Indicator Blink Timer Enable
0 = Indicator blink is disabled
1 = Indicator blink is enabled
B5
IND_RP_EN
INDLED Indicator Ramp-Up/Down Enable
0 = Indicator ramp-up/down is disabled
1= Indicator ramp-up/down is enabled
B4
B3
B2
B1
B0 (LSB)
IND[4:0]
DEFAULT VALUE
Reserved for future use
INDLED Indicator Mode Current Setting
00000 = 0.5mA
00001 = 1.0mA
00010 = 1.5mA
00011 = 2.0mA
00100 = 2.5mA
00101 = 3.0mA
00110 = 3.5mA
00111 = 4.0mA
01000 = 4.5mA
01001 = 5.0mA
01010 = 5.5mA
01011 = 6.0mA
01100 = 6.5mA
01101 = 7.0mA
01110 = 7.5mA
01111 = 8.0mA
10000 = 8.5mA
10001 = 9.0mA
10010 = 9.5mA
10011 = 10.0mA
10100 = 10.5mA
10101 = 11.0mA
10110 = 11.5mA
10111 = 12.0mA
11000 = 12.5mA
11001 = 13.0mA
11010 = 13.5mA
11011 = 14.0mA
11100 = 14.5mA
11101 = 15.0mA
11110 = 15.5mA
11111 = 16.0mA
00000
______________________________________________________________________________________
29
MAX8834Y/MAX8834Z
Table 6. IND_CUR
MAX8834Y/MAX8834Z
Adaptive Step-Up Converters
with 1.5A Flash Driver
Table 7. IND_CNTL
This register contains indicator LED ramp and blink timer control.
REGISTER NAME
IND_CNTL
Address
0x07
Reset Value
0x00
Type
Read/write
Special Features
BIT
—
NAME
IND_OFF
00
IND_ON
INDLED Indicator On Blink Timer Control
00 = 128ms
01 = 256ms
10 = 512ms
11 = 1024ms
00
IND_RU[1:0]
INDLED Indicator Ramp-Up Timer Control
00 = 128ms
01 = 256ms
10 = 512ms
11 = 1024ms
00
IND_RD[1:0]
INDLED Indicator Ramp-Down Timer Control
00 = 128ms
01 = 256ms
10 = 512ms
11 = 1024ms
00
B6
B5
B4
B3
B2
B1
30
DEFAULT VALUE
INDLED Indicator Off Blink Timer Control
00 = 512ms
01 = 1024ms
10 = 2048ms
11 = 4096ms
B7 (MSB)
B0 (LSB)
DESCRIPTION
______________________________________________________________________________________
Adaptive Step-Up Converters
with 1.5A Flash Driver
This register contains FLED1, FLED2 and INDLED on/off and mode control.
REGISTER NAME
LED_CNTL
Address
0x09
Reset Value
0x00
Type
Read/write
Special Features
BIT
—
NAME
B7 (MSB)
B6
IND_EN[1:0]
B5
B4
MOVIE_EN[2:0]
B3
B2
B1
B0 (LSB)
FLASH_EN[2:0]
DESCRIPTION
INDLED Indicator Current Regulator Enable
00 = INDLED indicator LED is disabled
01 = INDLED indicator LED is disabled
10 = INDLED indicator LED is enabled
11 = INDLED indicator LED is controlled by LED_EN input
FLED1/FLED2 MOVIE Mode Current Regulator Enable
000 = FLED1 and FLED2 movie mode disabled
001 = FLED1 movie mode is enabled, FLED2 movie mode is disabled
010 = FLED2 movie mode is enabled, FLED1 movie mode is disabled
011 = FLED1 and FLED2 movie mode is enabled
101 = FLED1 movie mode is controlled by LED_EN, FLED2 movie mode
is disabled
110 = FLED2 movie mode is controlled by LED_EN, FLED1 movie mode
is disabled
111 = FLED1 and FLED2 movie mode is controlled by LED_EN
FLED1/FLED2 Flash Mode Current Regulator Enable
000 = FLED1 and FLED2 flash mode disabled
001 = FLED1 flash mode is enabled, FLED2 flash mode is disabled
010 = FLED2 flash mode is enabled, FLED1 flash mode is disabled
011 = FLED1 and FLED2 flash mode is enabled
101 = FLED1 flash mode is controlled by LED_EN, FLED2 flash mode is
disabled
110 = FLED2 flash mode is controlled by LED_EN, FLED1 flash mode is
disabled
111 = FLED1 and FLED2 flash mode is controlled by LED_EN
DEFAULT VALUE
00
000
000
______________________________________________________________________________________
31
MAX8834Y/MAX8834Z
Table 8. LED_CNTL
MAX8834Y/MAX8834Z
Adaptive Step-Up Converters
with 1.5A Flash Driver
Table 9. TMR_DUR
This register contains watchdog timer and flash safety time-control values.
REGISTER NAME
Address
0x0A
Reset Value
0x00
Type
Read/write
Special Features
—
BIT
NAME
B7 (MSB)
WDT_EN
B6
B5
B4
WDT_DUR[1:0]
TMR_MODE
B3
B2
TMR_DUR [3:0]
B1
B0 (LSB)
32
TMR_DUR
DESCRIPTION
Enable/Disable Of Watchdog Timer Function
0 = WDT is disabled
1 = WDT is enabled
Watchdog Timer Duration
00 = 4s
01 = 8s
10 = 12s
11 = 16s
Safety Timer Control
0 = One-shot mode—generates a flash with a duration of TMR_DUR
regardless of LED:EN and I2C setting; pulling VDD low in this
condition terminates flash operating and puts the IC into power-down
mode
1 = Maximum timer mode—ensures that flash duration does not exceed
the timer defined in TMR:DUR
Safety Timer Duration Control
0000 = 50ms
0001 = 100ms
0010 = 150ms
0011 = 200ms
0100 = 250ms
0101 = 300ms
0110 = 350ms
0111 = 400ms
1000 = 450ms
1001 = 500ms
1010 = 550ms
1011 = 600ms
1100 = 650ms
1101 = 700ms
1110 = 750ms
1111 = 800ms
______________________________________________________________________________________
DEFAULT VALUE
0
00
0
0000
Adaptive Step-Up Converters
with 1.5A Flash Driver
This register contains NTC function control values.
REGISTER NAME
Address
0x0B
Reset Value
0x00
Type
Read/write
Special Features
BIT
B7 (MSB)
B6
NTC_CNTL
—
NAME
DESCRIPTION
Flash Safety Timer Reset Control
0 = Enable FLASH reset timer, only valid when FLASH mode is
enabled using the LED_EN; LED_EN needs to be pulled low for
FLASH_TMR_CNTL
minimum 30ms (typ) to reset the flash safety
1 = Disable FLASH reset timer; flash safety timer is reset as soon as
LED_EN is pulled low
—
Reserved for future use
DEFAULT VALUE
0
0
B5
—
Reserved for future use
0
B4
—
0
B3
NTC_EN
Reserved for future use
Finger-Burn Feature Enable
0 = Disable NTC function
1 = Enable NTC function
B2
B1
B0 (LSB)
NTC[2:0]
Finger-Burn Threshold Control
000 = 200mV
001 = 250mV
010 = 300mV
011 = 350mV
100 = 400mV
101 = 450mV
110 = 500mV
111 = 550mV
0
000
______________________________________________________________________________________
33
MAX8834Y/MAX8834Z
Table 10. NTC_CNTL
MAX8834Y/MAX8834Z
Adaptive Step-Up Converters
with 1.5A Flash Driver
Table 11. GSMB_CUR
This register contains FLED1 and FLED2 current control values for the GSMB function.
REGISTER NAME
GSMB_CUR
Address
0x0C
Reset Value
0xC0
Type
Read/write
Special Features
—
BIT
NAME
B7 (MSB)
GSMB_EN
GSM Blank Enable
0 = GSMB input is disabled
1 = GSMB input is enabled
1
B6
GSMB_POL
GSM Blank Polarity Control
0 = GSMB is active-low
1 = GSMB is active-high
1
B5
B4
ILIM[3:0]
B3
B2
B1
HC_TMR[1:0]
B0 (LSB)
34
DESCRIPTION
DEFAULT VALUE
Input Current Limit During GSMB
0000 = 50mA
0001 = 100mA
0010 = 150mA
0011 = 200mA
0100 = 250mA
0101 = 300mA
0110 = 350mA
0111 = 400mA
1000 = 450mA
1001 = 500mA
1010 = 550mA
1011 = 600mA
1100 = 650mA
1101 = 700mA
1110 = 750mA
1111 = 800mA
GSMB Reset Timer
00 = 10μs
01 = 20μs
10 = 40μs
11 = 80μs
______________________________________________________________________________________
0000
00
Adaptive Step-Up Converters
with 1.5A Flash Driver
This register contains MAXFLASH control function.
REGISTER NAME
Address
0x0D
Reset Value
0x00
Type
Read/write
Special Features
BIT
B7 (MSB)
—
NAME
LB_EN
LB_TH[4:0]
LB_HYS[1:0]
Low-Battery Detection Hysteresis
00 = 100mV
01 = 200mV
10 = Reserved for future use
11 = Hysteresis is disabled—flash current is only reduced
B5
B3
B2
B1
B0 (LSB)
DESCRIPTION
MAXFLASH Function Enable
0 = Disabled
1 = Low-battery function is enabled
Low-Battery Detection Threshold
00000 = 2.400V [Do not use]
00001 = 2.433V [Do not use]
00010 = 2.466V [Do not use]
00011 = 2.500V
00100 = 2.533V
00101 = 2.566V
00110 = 2.600V
00111 = 2.633V
01000 = 2.666V
01001 = 2.700V
01010 = 2.733V
01011 = 2.766V
01100 = 2.800V
01101 = 2.833V
01110 = 2.866V
01111 = 2.900V
10000 = 2.933V
10001 = 2.966V
10010 = 3.000V
10011 = 3.033V
10100 = 3.066V
10101 = 3.100V
10110 = 3.133V
10111 = 3.166V
11000 = 3.200V
11001 = 3.233V
11010 = 3.266V
11011 = 3.300V
11100 = 3.333V
11101 = 3.366V
11110 = 3.400V
11111 = 3.400V
B6
B4
MAXFLASH1
DEFAULT VALUE
0
00000
00
______________________________________________________________________________________
35
MAX8834Y/MAX8834Z
Table 12. MAXFLASH1
MAX8834Y/MAX8834Z
Adaptive Step-Up Converters
with 1.5A Flash Driver
Table 13. MAXFLASH2
This register contains MAXFLASH control function.
REGISTER NAME
MAXFLASH2
Address
0x0E
Reset Value
0x00
Type
Read/write
Special Features
—
BIT
NAME
B7 (MSB)
—
Reserved for future use
DESCRIPTION
0
B6
—
Reserved for future use
0
B4
—
Reserved for future use
0
B3
—
Reserved for future use
0
B3
—
Reserved for future use
0
B2
—
Reserved for future use
0
Low-Battery Reset Timer
00 = 0.250ms
01 = 0.500ms
10 = Reserved for future use
11 = Reserved for future use
00
B1
LB_TMR[1:0]
B0 (LSB)
DEFAULT VALUE
Table 14. WDT_RST
This register contains watchdog reset function.
REGISTER NAME
WDT_RST
Address
0x16
Reset Value
0x00
Type
Read/write
Special Features
BIT
NAME
DESCRIPTION
DEFAULT VALUE
B7 (MSB)
—
Reserved for future use
0
B6
—
Reserved for future use
0
B4
—
Reserved for future use
0
B3
—
Reserved for future use
0
B3
—
Reserved for future use
0
B2
—
Reserved for future use
0
B1
—
Reserved for future use
0
—
Watchdog Reset
0 = Default
1 = Writing a 1 resets the watchdog timer; after writing a 1, this bit is cleared
upon watchdog timer reset
—
B0 (LSB)
36
—
______________________________________________________________________________________
Adaptive Step-Up Converters
with 1.5A Flash Driver
This register contains status information.
REGISTER NAME
Address
STATUS1
0x17
Reset Value
N/A
Type
Read
Special Features
—
BIT
NAME
DESCRIPTION
DEFAULT VALUE
B7 (MSB)
NTC_FLT
NTC Status Readback
0 = NTC status OK
1 = Fault (short) occurred on NTC
0
B6
GSMB
GSMB Status Readback
0 = No GSMB event has occurred
1 = GSMB event has occurred
0
B5
POK_FLT
POK Window Cooperator Status Readback
0 = Output voltage is within POK window
1 = POK fault has occurred
0
B4
OVER_TEMP
Die Temperature Overload Condition Status Readback
0 = Die temp is within spec
1 = Die overtemp event has occurred
0
B3
NTC_OVT
NTC Status Readback
0 = NTC temperature is within spec
1 = NTC temperature threshold has tripped
0
B2
INDLED_FLT
INDLED Status Readback
0 = INDLED status is OK
1 = Fault (open/short) has occurred on INDLED
0
B1
FLED2_FLT
FLED2 Status Readback
0 = FLED2 status is OK
1 = Fault (open/short) has occurred on FLED2
0
B0 (LSB)
FLED1_FLT
FLED1 Status Readback
0 = FLED1 status is OK
1 = Fault (open/short) has occurred on FLED1
0
Note: All faults are latched. Bit(s) are cleared after reading register contents. If the fault is still present, the bit is set again.
______________________________________________________________________________________
37
MAX8834Y/MAX8834Z
Table 15. STATUS1
MAX8834Y/MAX8834Z
Adaptive Step-Up Converters
with 1.5A Flash Driver
Table 16. STATUS2
This register contains status information.
REGISTER NAME
STATUS2
Address
0x18
Reset Value
N/A
Type
Read
Special Features
BIT
—
NAME
DESCRIPTION
DEFAULT VALUE
B7 (MSB)
MAXFLASH_STAT
B6
GSMB_ILIM
B5
—
Indication of if MAXFLASH Function Has Been Triggered Since Last
Read Operation of This Register
0 = MAXFLASH event has not occurred
1 = MAXFLASH event has occurred
Indication of if Input Current Limit Has Been Reached During GSMB
Since Last Read Operation of This Register
0 = Input current limit not reached
1 = Input current limit reached
Reserved for future use
B4
—
Reserved for future use
0
B3
—
Reserved for future use
0
B2
—
Reserved for future use
0
B1
—
Reserved for future use
0
B0 (LSB)
—
Reserved for future use
0
0
0
0
Table 17. CHIP_ID1
This register contains the MAX8834Y/MAX8834Z die type number.
REGISTER NAME
CHIP_ID1
Address
0x1A
Reset Value
N/A
Type
Read
Special Features
BIT
—
NAME
DESCRIPTION
DEFAULT VALUE
B7 (MSB)
B6
B5
DIE_TYPE[7:4]
BCD Character 1
[0001]
DIE_TYPE[3:0]
BCD Character 1
[0001]
B4
B3
B2
B1
B0 (LSB)
Note: This register value is fixed in metal.
38
______________________________________________________________________________________
Adaptive Step-Up Converters
with 1.5A Flash Driver
This register contains the die type dash number (0 = plain) and mask revision level.
REGISTER NAME
CHIP_ID2
Address
0x1B
Reset Value
N/A
Type
Read
Special Features
BIT
—
NAME
DESCRIPTION
DEFAULT VALUE
B7 (MSB)
B6
DASH
B5
BCD Character representing dash number
—
BCD Character representing die revision
—
B4
B3
B2
MASK_REV
B1
B0 (LSB)
Applications Information
Inductor Selection
See Table 19 for a list of recommended inductors. To
prevent core saturation, ensure that the inductor saturation current rating exceeds the peak inductor current
for the application. Calculate the worst-case peak
inductor current as follows:
IPEAK =
VOUT × IOUT(MAX)
0.9 × VIN(MIN)
+
VIN(MIN)
2 × fSW × L
where fSW is the switching frequency.
Capacitor Selection
Bypass IN to AGND and PGND with a ceramic capacitor. Ceramic capacitors with X5R and X7R dielectrics are
recommended for their low ESR and tighter tolerances
over wide temperature ranges. Place the capacitor as
close as possible to the IC. The recommended minimum
value for the input capacitor is 10µF; however, larger
value capacitors can be used to reduce input ripple at
the expense of size and higher cost.
The output capacitance required depends on the output current. A 10µF ceramic capacitor works well in
most situations, but a 4.7µF ceramic capacitor is
acceptable for lower load currents.
Compensation Network Selection
The step-up converter is compensated for stability
through an external compensation network from COMP
to AGND. See Table 20 for recommended compensation networks.
PCB Layout
Due to fast-switching waveforms and high-current
paths, careful PCB layout is required. Connect AGND,
FGND, and PGND directly to the ground plane. The IN
bypass capacitor should be placed as close as possible to the IC. RCOMP and CCOMP should be connected
between COMP and AGND as close as possible to the
IC. Minimize trace lengths between the IC and the
inductor, the input capacitor, and the output capacitor;
keep these traces short, direct, and wide. The ground
connections of C IN and C OUT should be as close
together as possible and connected to PGND. The
traces from the input to the inductor and from the output capacitor to the LEDs may be longer. Figure 21
illustrates an example PCB layout and routing scheme.
Refer to the MAX8834Y/MAX8834Z Evaluation Kit for a
PCB layout example.
______________________________________________________________________________________
39
MAX8834Y/MAX8834Z
Table 18. CHIP_ID2
MAX8834Y/MAX8834Z
Adaptive Step-Up Converters
with 1.5A Flash Driver
Table 19. Suggested Inductors
MANUFACTURER
Coilcraft
Taiyo Yuden
TOKO
PART/SERIES
INDUCTANCE (μH)
DCR (m)
ISAT (A)
DIMENSIONS
(lTYP x W TYP x HMAX)
(mm)
LPS4012-222ML
2.2
100
2.3
4 x 4 x 1.1
LPS4018-222ML
2.2
70
2.7
4 x 4 x 1.7
LPS5030-220ML
2.2
57
3.1
5 x 5 x 2.9
LPS6225-222ML
2.2
45
3.9
6.2 x 6.2 x 2.5
LPO3310-102ML
1
76
1.6
3x3x1
LPS3015-102ML
1
75
1.6
3x3x1
LPO3010-102NLC
1
140
1.7
3x3x1
DO3314-102ML
1
110
2.1
3 x 3 x 1.4
LPS3314-102ML
1
45
2.3
3 x 3 x 1.4
DP1605T-102ML
1
40
2.5
4 x 4 x 1.8
LPS4012-102ML
1
60
2.8
4 x 4 x 1.1
LPS4018-102ML
1
40
2.8
4 x 4 x 1.7
LPS5015-102ML
1
50
3.8
5 x 5 x 1.5
NR4018T2R2M
2.2
72
2.7
4 x 4 x 1.8
NR3012T1R0N
1
60
1.5
3 x 3 x 1.2
NR4010T1R0N
1
120
1.8
4x4x1
NR3015T1R0N
1
36
2.1
3 x 3 x 1.5
NR4012T1R0N
1
72
2.5
4 x 4 x 1.2
4 x 4 x 1.8
NP03SB1R0M
1
27
2.6
NP04SZB1R0N
1
30
4
5x5x2
NR4018T1R0N
1
36
4
4 x 4 x 1.8
1117AS-1R2N
1.2
65
1.2
3x3x1
1098AS-1R2N
1.2
56
1.8
3 x 3 x 1.2
A997AS-1R0N
1
40
1.8
4 x 4 x 1.8
1072AS-1R0N
1
30
1.95
3 x 3 x 1.8
1071AS-1R0N
1
40
2.1
3 x 3 x 1.5
Table 20. Suggested Compensation
Networks
INDUCTANCE
RCOMP
(k)
CCOMP
(pF)
1.0μH Inductor (dynamic loads)
5.5
2200
2.2μH Inductor (dynamic loads)
4.3
2200
4.7μH Inductor (dynamic loads)
3
4700
10μH Inductor (dynamic loads)
3
6800
Other (non-LED) Loads (1μH to 10μH)
0 (short)
22000
40
______________________________________________________________________________________
Adaptive Step-Up Converters
with 1.5A Flash Driver
MAX8834Y/MAX8834Z
L
6.0mm
COUT
CIN
OUT
LX
PGND
IN
VDD
A1
A2
A3
A4
A5
OUT
LX
PGND
SCL
AGND
B1
B2
B3
B4
B5
COMP
FGND
LED_EN
GSMB
SDA
C1
C2
C3
C4
C5
FLED2
FGND
FLED1
INDLED
NTC
D1
D2
D3
D4
D5
CVDD
CCOMP
FLASH2
LED CATHODE
FLASH1
LED CATHODE
INDICATOR
LED CATHODE
3.8mm
Figure 21. Recommended PCB Layout
______________________________________________________________________________________
41
Adaptive Step-Up Converters
with 1.5A Flash Driver
MAX8834Y/MAX8834Z
Block Diagram and Typical Application Circuit
1μH
LX
OUT
IN
VIN
2.5V TO 5.5V
CIN
10μF
AGND
UVLO AND
POWER
INPUT
CURRENT
LIMIT
COMP
CCOMP
COUT
10μF
PWM STEP-UP
CONVERTER
ADAPTIVE/
FIXED
OUTPUT
SELECT
PGND
PROGRAMMABLE
OUTPUT
3.7V TO 5.2V
VREF
VREG
2MHz OR 4MHz
SELECT
MIN
RCOMP
FLASH
TIMER
VPOK
750mA
WATCHDOG
TIMER
NTC
RNTC
100kΩ
GSMB
REGISTERS
AND
CONTROL
LOGIC
PA_EN
1MHz
VLOGIC
1.62V TO 3.6V
750mA
16mA
SAMPLING
LOGIC
FGND
VDD
CVDD
0.1μF
42
FLED2
INDLED
FLASH/MOVIE LED_EN
STROBE
I2C
INTERFACE
FLED1
SDA
SCL
I2 C
INTERFACE
MAX8834Y
MAX8834Z
______________________________________________________________________________________
Adaptive Step-Up Converters
with 1.5A Flash Driver
Chip Information
PROCESS: BiCMOS
TOP VIEW
(BUMPS ON BOTTOM)
1
2
3
4
5
MAX8834Y/MAX8834Z
A
B
C
D
Package Information
For the latest package outline information and land patterns, go
to www.maxim-ic.com/packages.
A1
A2
A3
A4
A5
PACKAGE TYPE
PACKAGE CODE
DOCUMENT NO.
OUT
LX
PGND
IN
VDD
20 WLP
W202A2+2
21-0059
B1
B2
B3
B4
B5
OUT
LX
PGND
SCL
AGND
C1
C2
C3
C4
C5
COMP
FGND
LED_EN
GSMB
SDA
D1
D2
D3
D4
D5
FLED2
FGND
FLED1
INDLED
NTC
WLP
(2.5mm × 2.0mm)
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 43
© 2009 Maxim Integrated Products
Maxim is a registered trademark of Maxim Integrated Products, Inc.
MAX8834Y/MAX8834Z
Pin Configuration