19-2883; Rev 0; 7/03
5-Channel Slim DSC Power Supplies
The MAX1584/MAX1585 provide a complete powersupply solution for slim digital cameras. They improve
performance, component count, and size compared to
conventional multichannel controllers in 2-cell AA, 1-cell
Li+, and dual-battery designs. On-chip MOSFETs provide up to 95% efficiency for critical power supplies,
while additional channels operate with external FETs for
optimum design flexibility. This optimizes overall efficiency and cost, while also reducing board space.
The MAX1584/MAX1585 include 5 high-efficiency DCDC conversion channels:
• Step-up DC-DC converter with on-chip FETs
• Step-down DC-DC converter with on-chip FETs
• Three PWM DC-DC controllers for CCD, LCD, LED,
or other functions
The step-down DC-DC converter can operate directly
from the battery or from the step-up output, providing
boost-buck capability with a compound efficiency of up
to 90%. Both devices include three PWM DC-DC controllers: the MAX1584 includes two step-up controllers
and one step-down controller, while the MAX1585
includes one step-up controller, one inverting controller,
and one step-down controller. All DC-DC channels
operate at one fixed frequency—settable from 100kHz
to 1MHz—to optimize size, cost, and efficiency. Other
features include soft-start, power-OK outputs, and overload protection. The MAX1584/MAX1585 are available
in space-saving, 32-pin thin QFN packages. An evaluation kit is available to expedite designs.
Features
♦ Step-Up DC-DC Converter, 95% Efficient
♦ Step-Down DC-DC Converter
Operate from Battery for 95% Efficient
Step-Down
90% Efficient Boost-Buck with Step-Up
♦ Three Auxiliary PWM DC-DC Controllers
♦ No Transformers (MAX1585)
♦ Up to 1MHz Operating Frequency
♦ 1mA Shutdown Mode
♦ Internal Soft-Start Control
♦ Overload Protection
♦ Compact 32-Pin Thin QFN Package (5mm x 5mm)
Ordering Information
PINPACKAGE
AUX
FUNCTIONS
MAX1584ETJ -40°C to +85°C
32 Thin QFN
5mm x 5mm
2 step-up
1 step-down
MAX1585ETJ -40°C to +85°C
32 Thin QFN
5mm x 5mm
1 step-up
1 step-down
1 inverting
PART
TEMP RANGE
Pin Configuration
Applications
Typical Operating Circuit
MAX1585
GND
DL1
DL3
DL2
PV
INDL2
28
27
26
25
24
CC2
FB1
2
23
FB2
PGSD
3
22
PVSU
LXSD
4
21
LXSU
MAX1584
MAX1585
PVSD
5
20
PGSU
ONSD
6
19
OSC
CCSD
7
18
SCF
FBSD
8
17
SDOK
CCD -7.5V
AUX3
LOGIC +3.3V
10
11
12
13
14
15
16
AUX1OK
AUX2
9
CCSU
LCD, CCD, LED +15V
FBSU
CORE +1.8V
REF
AUX1
29
ON1
ONSU
ONSD
ON1
ON2
ON3
30
ONSU
STEP-DOWN
SYSTEM +5V
31
1
ON3
STEP-UP
32
CC1
ON2
INPUT
0.7V TO 5.5V
CC3
PDAs
FB3
Digital Cameras
THIN QFN
5mm x 5mm
________________________________________________________________ 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
MAX1584/MAX1585
General Description
MAX1584/MAX1585
5-Channel Slim DSC Power Supplies
ABSOLUTE MAXIMUM RATINGS
PV, PVSU, PVSD, SDOK, AUX1OK, SCF, ON_, FB_ to
GND..........................................................................-0.3V to +6V
PGND to GND....................................................…-0.3V to +0.3V
INDL2, DL1, DL3 to GND.........................-0.3V to (PVSU + 0.3V)
DL2 to GND ............................................-0.3V to (INDL2 + 0.3V)
PV to PVSU ...........................................................-0.3V to + 0.3V
LXSU Current (Note 1) ..........................................................3.6A
LXSD Current (Note 1) ........................................................2.25A
REF, OSC, CC_ to GND...........................-0.3V to (PVSU + 0.3V)
Continuous Power Dissipation (TA = +70°C)
32-Pin Thin QFN (derate 22mW/°C above +70°C) ....1700mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Note 1: LXSU has internal clamp diodes to PVSU and PGND, and LXSD has internal clamp diodes to PVSD and PGND. Applications
that forward bias these diodes should take care not to exceed the device’s power dissipation limits.
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
(VPVSU = VPV = VPVSD = VINDL2 = 3.6V, TA = 0°C to +85°C, unless otherwise noted.)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
5.5
V
GENERAL
Input Voltage Range
(Note 2)
0.7
Step-Up Minimum Startup
Voltage
ILOAD < 1mA, TA = +25°C, startup voltage tempco is
-2300ppm/°C (typ) (Note 3)
0.9
1.1
V
Shutdown Supply Current into PV
PV = 3.6V
0.1
5
µA
Supply Current into PV with
Step-Up Enabled
ONSU = 3.6V, FBSU = 1.5V
(does not include switching losses)
300
450
µA
Supply Current into PV with
Step-Up and Step-Down Enabled
ONSU = ONSD = 3.6V, FBSU = 1.5V, FBSD = 1.5V
(does not include switching losses)
450
700
µA
Total Supply Current from PV and
PVSU with Step-Up and One AUX
Enabled
ONSU = ON1 = 3.6V, FBSU = 1.5V, FB2 = 1.5V
(does not include switching losses)
400
650
µA
REFERENCE
Reference Output Voltage
IREF = 20µA
1.25
1.27
V
Reference Load Regulation
10µA < IREF < 200µA
1.23
4.5
10
mV
Reference Line Regulation
2.7 < PVSU < 5.5V
1.3
5
mV
1.25
1.275
V
52
80
Ω
OSCILLATOR
OSC Discharge Trip Level
Rising edge
OSC Discharge Resistance
OSC = 1.5V, IOSC = 3mA
1.225
OSC Discharge Pulse Width
OSC Frequency
ROSC = 47kΩ, COSC =100pF
150
ns
500
kHz
STEP-UP DC-DC CONVERTER
Step-Up Startup-to-Normal
Operating Threshold
Step-Up Startup-to-Normal
Operating Threshold Hysteresis
2
Rising edge or falling edge (Note 4)
2.30
2.5
80
_______________________________________________________________________________________
2.65
V
mV
5-Channel Slim DSC Power Supplies
(VPVSU = VPV = VPVSD = VINDL2 = 3.6V, TA = 0°C to +85°C, unless otherwise noted.)
PARAMETER
CONDITIONS
Step-Up Voltage Adjust Range
MIN
TYP
3.0
Start Delay of ONSD, ON1, ON2,
ON3 after SU in Regulation
MAX
UNITS
5.5
V
OSC
cycles
1024
FBSU Regulation Voltage
1.231
1.25
1.269
V
FBSU to CCSU
Transconductance
FBSU = CCSU
80
135
185
µS
FBSU Input Leakage Current
FBSU = 1.25V
-100
+1
+100
nA
TM
Idle Mode
Trip Level
(Note 6)
Current-Sense Amplifier
Transresistance
mA
0.275
V/A
Step-Up Maximum Duty Cycle
FBSU = 1V
85
90
%
PVSU Leakage Current
VLX = 0V, PVSU = 5.5V
0.1
5
µA
LXSU Leakage Current
VLXSU = VOUT = 5.5V
0.1
5
µA
N channel
95
150
P channel
150
250
2.8
3.2
Switch On-Resistance
N-Channel Current Limit
80
150
2.4
P-Channel Turn-Off Current
mΩ
A
20
mA
mA
Startup Current Limit
PVSU = 1.8V (Note 5)
450
Startup tOFF
PVSU = 1.8V
700
ns
Startup Frequency
PVSU = 1.8V
200
kHz
STEP-DOWN DC-DC CONVERTER
Step-Down Output Voltage
Adjust Range
PVSD must be greater than output (Note 7)
FBSD Regulation Voltage
1.25
5.00
V
1.231
1.25
1.269
V
µS
FBSD to CCSD
Transconductance
FBSD = CCSD
80
135
185
FBSD Input Leakage Current
FBSD = 1.25V
-100
+0.1
+100
Idle Mode Trip Level
(Note 6)
Current-Sense Amplifier
Transresistance
LXSD Leakage Current
Switch On-Resistance
VLXSD = 0 to 3.6V, PVSU = 3.6V
mA
0.5
V/A
0.1
5
N channel
95
150
P channel
150
250
0.8
0.95
P-Channel Current Limit
0.65
N-Channel Turn-Off Current
Soft-Start Interval
nA
100
µA
mΩ
A
20
mA
2048
OSC
cycles
SDOK Output Low Voltage
0.1mA into SDOK
0.01
0.1
V
SDOK Leakage Current
ONSU = GND
0.01
1
µA
Idle Mode is a trademark of Maxim Integrated Products, Inc.
_______________________________________________________________________________________
3
MAX1584/MAX1585
ELECTRICAL CHARACTERISTICS (continued)
MAX1584/MAX1585
5-Channel Slim DSC Power Supplies
ELECTRICAL CHARACTERISTICS (continued)
(VPVSU = VPV = VPVSD = VINDL2 = 3.6V, TA = 0°C to +85°C, unless otherwise noted.)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
80
85
90
%
AUX1, 2, 3 DC-DC CONTROLLERS
Maximum Duty Cycle
FB_ = 1V
FB1 and FB3 Regulation Voltage
FB_ = CC_
1.231
1.25
1.269
V
FB2 (MAX1584) Regulation
Voltage
FB_ = CC_
1.231
1.25
1.269
V
FB2 (MAX1585) (Inverter)
Regulation Voltage
FB_ = CC_
-0.01
0
+0.01
V
FB_ to CC_ Transconductance
FB_ = CC_
80
135
185
µS
FB_ Input Leakage Current
FB_ = 1.25V
+1
+100
nA
DL_ Driver Resistance
Output high or low
2.5
10
Ω
DL_ Drive Current
Sourcing or sinking
0.5
A
4096
OSC
cycles
-100
Soft-Start Interval
AUX1OK Output Low Voltage
0.1mA into AUX1OK
0.01
0.1
V
AUX1OK Leakage Current
ONSU = GND
0.01
1
µA
OVERLOAD AND THERMAL PROTECTION
Overload-Protection Fault Delay
OSC
cycles
100,000
SCF Leakage Current
ONSU = PVSU, FBSU = 1.5V
0.1
1
SCF Output Low Voltage
0.1mA into SCF
0.01
0.1
µA
V
Thermal Shutdown
+160
°C
Thermal Hysteresis
20
°C
LOGIC INPUTS
ON_ Input Low Level
ON_ Input High Level
1.1V < PVSU < 1.8V (ONSU only)
0.2
1.8V < PVSU< 5.5V
0.4
1.1V < PVSU < 1.8V (ONSU only)
1.8V < PVSU < 5.5V
ON_ Impedance to GND
4
ON_ = 3.35V
VPVSU 0.2
V
V
1.6
330
_______________________________________________________________________________________
kΩ
5-Channel Slim DSC Power Supplies
(VPVSU = VPV = VPVSD = VINDL2 = 3.6V, TA = -40°C to +85°C, unless otherwise noted.) (Note 8)
PARAMETER
CONDITIONS
MIN
MAX
UNITS
0.7
5.5
V
5
µA
GENERAL
Input Voltage Range
(Note 2)
Shutdown Supply Current
into PVSU
PVSU = 3.6V
Supply Current into PV with
Step-Up Enabled
ONSU = 3.6V, FBSU = 1.5V
(does not include switching losses)
450
µA
Supply Current into PV with
Step-Up and Step-Down Enabled
ONSU = ONSD = 3.6V, FBSU = 1.5V, FBSD = 1.5V
(does not include switching losses)
700
µA
Total Supply Current from PV and
PVSU with Step-Up and One AUX
Enabled
ONSU = ON1 = 3.6V, FBSU = 1.5V, FB2 = 1.5V
(does not include switching losses)
650
µA
REFERENCE
Reference Output Voltage
IREF = 20µA
1.275
V
Reference Load Regulation
10µA < IREF < 200µA
1.225
10
mV
Reference Line Regulation
2.7V < PVSU < 5.5V
5
mV
OSCILLATOR
OSC Discharge Trip Level
Rising edge
OSC Discharge Resistance
OSC = 1.5V, IOSC = 3mA
1.225
1.275
V
80
Ω
2.65
V
STEP-UP DC-DC CONVERTER
Step-Up Startup-to-Normal
Operating Threshold
Rising edge or falling edge (Note 4)
Step-Up Voltage Adjust Range
FBSU Regulation Voltage
2.30
3.0
5.5
V
1.225
1.275
V
FBSU to CCSU
Transconductance
FBSU = CCSU
80
185
µS
FBSU Input Leakage Current
FBSU = 1.25V
-100
+100
nA
Step-Up Maximum Duty Cycle
FBSU = 1V
80
90
%
PVSU Leakage Current
VLX = 0V, PVSU = 5.5V
5
µA
LXSU Leakage Current
VLXSU = VOUT = 5.5V
5
µA
Switch On-Resistance
N channel
150
P channel
250
N-Channel Current Limit
mΩ
2.4
3.2
A
1.25
5.00
V
STEP-DOWN DC-DC CONVERTER
Step-Down Output Voltage Adjust
Range
PVSD must be greater than output (Note 7)
_______________________________________________________________________________________
5
MAX1584/MAX1585
ELECTRICAL CHARACTERISTICS
MAX1584/MAX1585
5-Channel Slim DSC Power Supplies
ELECTRICAL CHARACTERISTICS (continued)
(VPVSU = VPV = VPVSD = VINDL2 = 3.6V, TA = -40°C to +85°C, unless otherwise noted.) (Note 8)
PARAMETER
CONDITIONS
FBSD Regulation Voltage
MIN
MAX
UNITS
1.225
1.275
V
FBSD to CCSD
Transconductance
FBSD = CCSD
80
185
µS
FBSD Input Leakage Current
FBSD = 1.25V
-100
+100
nA
LXSD Leakage Current
VLXSD = 0 to 3.6V, PVSU = 3.6V
5
µA
Switch On-Resistance
N channel
150
P channel
250
P-Channel Current Limit
0.65
SDOK Output Low Voltage
0.1mA into SDOK
SDOK Leakage Current
ONSU = GND
0.95
mΩ
A
0.1
V
1
µA
AUX1, 2, 3 DC-DC CONTROLLERS
Maximum Duty Cycle
FB_ = 1V
80
90
%
FB1 and FB3 Regulation Voltage
FB_ = CC_
1.225
1.275
V
FB2 (MAX1584) Regulation
Voltage
FB_ = CC_
1.225
1.275
V
FB2 (MAX1585) (Inverter)
Regulation Voltage
FB_ = CC_
-0.01
+0.01
V
FB_ to CC_ Transconductance
FB_ = CC_
80
185
µS
FB_ Input Leakage Current
FB_ = 1.25V
-100
+100
nA
DL_ Driver Resistance
Output high or low
10
Ω
AUX1OK Output Low Voltage
0.1mA into AUX1OK
0.1
V
AUX1OK Leakage Current
ONSU = GND
1
µA
OVERLOAD AND THERMAL PROTECTION
SCF Leakage Current
ONSU = PVSU, FBSU = 1.5V
1
µA
SCF Output Low Voltage
0.1mA into SCF
0.1
V
1.1V < PVSU < 1.8V (ONSU only)
0.2
1.8V < PVSU < 5.5V
0.4
LOGIC INPUTS
ON_ Input Low Level
ON_ Input High Level
1.1V < PVSU < 1.8V (ONSU only)
1.8V < PVSU < 5.5V
VPVSU - 0.2
1.6
V
V
Note 2: The MAX1584/MAX1585 are powered from the step-up output (PVSU). An internal low-voltage startup oscillator drives the
step-up starting at about 0.9V until PVSU reaches approximately 2.5V. When PVSU reaches 2.5V, the main control circuitry
takes over. Once the step-up is up and running, it can maintain operation with very low input voltages; however, output current is limited.
Note 3: Since the device is powered from PVSU, a Schottky rectifier, connected from the input battery to PVSU, is required for lowvoltage startup, or if PVSD is connected to VIN instead of PVSU.
Note 4: The step-up regulator is in startup mode until this voltage is reached. Do not apply full load current during startup. A powerOK output can be used with an external PFET to gate the load until the step-up is in regulation. See the Applications
Information section.
6
_______________________________________________________________________________________
5-Channel Slim DSC Power Supplies
(VPVSU = VPV = VPVSD = VINDL2 = 3.6V, TA = -40°C to +85°C, unless otherwise noted.) (Note 8)
Note 5: The step-up current limit in startup refers to the LXSU switch current limit, not an output current limit.
Note 6: The idle mode current threshold is the transition point between fixed-frequency PWM operation and idle mode operation
(where switching rate varies with load). The specification is given in terms of inductor current. In terms of output current, the
idle mode transition varies with input-output voltage ratio and inductor value. For the step-up, the transition output current is
approximately 1/3 the inductor current when stepping from 2V to 3.3V. For the step-down, the transition current in terms of
output current is approximately 3/4 the inductor current when stepping down from 3.3V to 1.8V.
Note 7: Operation in dropout (100% duty cycle) can only be maintained for 100,000 OSC cycles before the output is considered
faulted, triggering global shutdown.
Note 8: Specifications to -40°C are guaranteed by design, not production tested.
Typical Operating Characteristics
(Circuit of Figure 1, TA = +25°C, unless otherwise noted.)
STEP-DOWN EFFICIENCY
vs. LOAD CURRENT
VIN = 4.5V
VIN = 4.2V
VIN = 3.8V
VIN = 3.0V
40
60
40
30
30
20
20
10
1
10
100
PVSD CONNECTED TO BATTERY
VOUT = 1.5V
DOES NOT INCLUDE CURRENT USED
BY THE STEP-UP TO POWER THE IC
10
VOUT = 5V
0
VIN = 3.0V
VIN = 3.8V
VIN = 4.2V
VIN = 4.5V
50
80
VOUT3 = 3.3V
VOUTSU = 5.0V
20
10
1
10
100
1
1000
10
100
LOAD CURRENT (mA)
EFFICIENCY vs. INPUT VOLTAGE
AUX1 EFFICIENCY vs. LOAD CURRENT
MAX1585 AUX2 EFFICIENCY
vs. LOAD CURRENT
MAX1584/85 toc04
100
90
80
SU = 5V, 300mA
SD = 1.5V, 250mA
SU + AUX3 = 3.3V, 300mA
AUX1 = 15V, 40mA
AUX2 = -7.5V, 40mA
EFFICIENCY (%)
EFFICIENCY (%)
85
VIN = 4.5V
VIN = 4.2V
VIN = 3.8V
VIN = 3.0V
70
60
50
VIN = 3.0V
VIN = 3.8V
VIN = 4.2V
VIN = 4.5V
60
50
VOUT1 = 15V
30
3.5
70
40
40
70
4.0
INPUT VOLTAGE (V)
4.5
1000
90
80
90
3.0
40
LOAD CURRENT (mA)
95
75
50
LOAD CURRENT (mA)
100
80
VIN = 4.5V
VIN = 4.2V
VIN = 3.8V
VIN = 3.0V
60
30
0
1000
70
MAX5184/85 toc06
50
70
90
MAX5184/85 toc05
60
80
EFFICIENCY (%)
70
90
EFFICIENCY (%)
EFFICIENCY (%)
80
100
MAX1584/85 toc02
90
EFFICIENCY (%)
100
MAX1584/85 toc01
100
COMBINED BOOST-BUCK
EFFICIENCY vs. LOAD CURRENT
MAX1584/85 toc03
STEP-UP EFFICIENCY
vs. LOAD CURRENT
VOUT2 = -7.5V
30
1
10
100
LOAD CURRENT (mA)
1000
1
10
100
1000
LOAD CURRENT (mA)
_______________________________________________________________________________________
7
MAX1584/MAX1585
ELECTRICAL CHARACTERISTICS (continued)
Typical Operating Characteristics (continued)
(Circuit of Figure 1, TA = +25°C, unless otherwise noted.)
MINIMUM STARTUP VOLTAGE
vs. LOAD CURRENT (VSU)
NO-LOAD INPUT CURRENT
vs. INPUT VOLTAGE (SWITCHING)
BOOST-BUCK (SU + AUX3)
VSU = 5.0V, OUT3 = 3.33V
6
5
4
3
2
3.0
2.5
1.5
1.0
0.5
VSU = 5.0V
1
0
0
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
200
400
600
800
1000
INPUT VOLTAGE (V)
LOAD CURRENT (mA)
REFERENCE VOLTAGE
vs. TEMPERATURE
REFERENCE VOLTAGE
vs. REFERENCE LOAD CURRENT
MAX1584/85 toc09
1.254
1.251
1.248
1.246
1.250
1.249
REFERENCE VOLTAGE (V)
0
REFERENCE VOLTAGE (V)
SCHOTTKY DIODE CONNECTED
FROM IN TO VSU
2.0
MAX1584/85 toc10
INPUT CURRENT (mA)
7
3.5
MAX5184/85 toc08
8
MINIMUM STARTUP VOLTAGE (V)
MAX1584/85 toc07
9
1.248
1.247
1.246
1.245
1.243
1.244
-25
0
25
50
75
100
0
50
100
150
200
REFERENCE LOAD CURRENT (μA)
OSCILLATOR FREQUENCY vs. ROSC
SWITCHING FREQUENCY
vs. TEMPERATURE
COSC = 470pF
900
COSC = 330pF
COSC = 220pF
700
COSC = 100pF
COSC = 47pF
500
300
510
509
508
507
506
505
504
503
100
ROSC= 51kΩ
COSC= 100pF
502
-100
300
MAX1584/85 toc12
MAX1584/85 toc11
1100
501
1
10
100
ROSC (kΩ)
8
250
TEMPERATURE (°C)
SWITCHING FREQUENCY (kHz)
-50
OSCILLATOR FREQUENCY (kHz)
MAX1584/MAX1585
5-Channel Slim DSC Power Supplies
1000
-50
-25
0
25
50
75
TEMPERATURE (°C)
_______________________________________________________________________________________
100
5-Channel Slim DSC Power Supplies
AUX MAXIMUM DUTY CYCLE
vs. FREQUENCY
WHEN THIS DUTY CYCLE IS EXCEEDED
FOR 100,000 CLOCK CYCLES,
THE MAX1584/MAX1585 SHUT DOWN
86
MAX1584/85 toc13
MAXIMUM DUTY CYCLE (%)
87
STEP-UP STARTUP RESPONSE
MAX1584/85 toc14
88
ONSU
5V/div
OUTSU
5V/div
IOUTSU
200mA/div
0V
85
0V
84
0A
83
82
IIN
1.0A/div
0A
81
COSC = 330pF
VIN = 3.5V
80
0 100 200 300 400 500 600 700 800 900 1000
200μs/div
FREQUENCY (kHz)
STEP-DOWN STARTUP RESPONSE
AUX1 STARTUP RESPONSE
MAX1584/85 toc15
MAX1584/85 toc16
ONSD
5V/div
OUTSD
5V/div
0V
0V
ON1
5V/div
OUT1
10V/div
0V
0V
IOUTSD
200mA/div
IOUT1
100mA/div
0A
0A
VIN = 3.5V
VIN = 3.5V
4ms/div
2ms/div
STEP-UP LOAD-TRANSIENT RESPONSE
STEP-DOWN LOADTRANSIENT RESPONSE
MAX1584/85 toc17
VOUTSU
AC-COUPLED
500mV/div
0V
0A
MAX1584/85 toc18
IOUT_SU
200mA/div
VOUTSU = 5.0V
VIN = 3.5V
400μs/div
VOUTSD
AC-COUPLED
100mV/div
0V
0A
VIN = 3.5V
VOUT_SD = 1.5V
IOUT_SD
100mA/div
400μs/div
_______________________________________________________________________________________
9
MAX1584/MAX1585
Typical Operating Characteristics (continued)
(Circuit of Figure 1, TA = +25°C, unless otherwise noted.)
5-Channel Slim DSC Power Supplies
MAX1584/MAX1585
Pin Description
10
PIN
NAME
FUNCTION
1
CC1
AUX1 Controller Compensation Node. Connect a series resistor-capacitor from CC1 to GND to
compensate the converter control loop. This pin is actively driven to GND in shutdown, overload, and
thermal limit. See the AUX Compensation section.
2
FB1
AUX1 Controller Feedback Input. The feedback threshold is 1.25V. This pin is high impedance in
shutdown.
3
PGSD
Step-Down Power Ground. Connect all PG_ pins together and to GND with short traces as close as
possible to the IC.
4
LXSD
Step-Down Converter Switching Node. Connect to the inductor of the step-down converter. LXSD is high
impedance in shutdown.
5
PVSD
Step-Down Converter Input. PVSD can connect to PVSU, effectively making OUTSD a boost-buck output
from the battery. Bypass to GND with a 1µF ceramic capacitor if connected to PVSU. PVSD can also be
connected to the battery but should not exceed PVSU by more than a Schottky diode forward voltage.
Bypass PVSD with a 10µF ceramic capacitor when connecting to the battery input. A 10kΩ internal
resistance connects PVSU and PVSD.
6
ONSD
Step-Down Converter On/Off Control Input. Logic high = on; however, turn-on is locked out until the stepup has reached regulation. This pin has an internal 330kΩ pulldown resistance to GND.
7
CCSD
Step-Up Converter Compensation Node. Connect a series resistor-capacitor from CCSD to GND to
compensate the converter control loop. This pin is actively driven to GND in shutdown, overload, and
thermal limit. See the Step-Down Compensation section.
8
FBSD
Step-Down Converter Feedback Input. Connect a resistive voltage-divider from OUTSD to FBSD to GND.
The FBSD feedback threshold is 1.25V. This pin is high impedance in shutdown.
9
ON1
AUX1 Controller On/Off Input. Logic high = on; however, turn-on is locked out until 1024 OSC cycles after
the step-up has reached regulation. This pin has an internal 330kΩ pulldown resistance to GND.
10
ON2
AUX2 Controller On/Off Input. Logic high = on; however, turn-on is locked out until 1024 OSC cycles after
the step-up has reached regulation. This pin has an internal 330kΩ pulldown resistance to GND.
11
ON3
AUX3 Controller On/Off Input. Logic high = on; however, turn-on is locked out until 1024 OSC cycles after
the step-up has reached regulation. This pin has an internal 330kΩ pulldown resistance to GND.
12
ONSU
13
REF
Reference Output. Bypass REF to GND with a 0.1µF or greater capacitor. The maximum allowed load on
REF is 200µA. REF is actively pulled to GND when all converters are shut down.
14
FBSU
Step-Up Converter Feedback Input. Connect a resistive voltage-divider from PVSU to FBSU to GND. The
FBSU feedback threshold is 1.25V. This pin is high impedance in shutdown.
15
CCSU
Step-Up Converter Compensation Node. Connect a series resistor-capacitor from CCSU to GND to
compensate the converter control loop. This pin is actively driven to GND in shutdown, overload, and
thermal limit. See the Step-Up Compensation section.
Step-Up Converter On/Off Control. Logic high = on. All other ON_ pins are locked out until 1024 OSC
cycles after the step-up DC-DC converter output has reached its final value. This pin has an internal
330kΩ pulldown resistance to GND.
______________________________________________________________________________________
5-Channel Slim DSC Power Supplies
PIN
NAME
16
AUX1OK
17
SDOK
FUNCTION
Open-Drain Power-OK Signal for AUX1 Controller. AUX1OK is low when the AUX1 controller has
successfully completed soft-start. This pin is high impedance in shutdown, overload, and thermal limit.
Open-Drain Power-OK Signal for Step-Down Converter. SDOK is low when the step-down has successfully
completed soft-start. This pin is high impedance in shutdown, overload, and thermal limit.
18
SCF
Short-Circuit Flag, Active-Low, Open-Drain Output. SCF is high impedance when overload protection
occurs and during startup. SCF can drive high-side PFET switches connected to one or more outputs to
completely disconnect the load when the channel turns off in response to a logic command or an
overload. See the Status Outputs (SDOK, AUX1OK, SCF) section.
19
OSC
Oscillator Control. Connect a timing capacitor from OSC to GND and a timing resistor from OSC to PVSU
(or other DC voltage) to set the oscillator frequency between 100kHz and 1MHz. See the Setting the
Switching Frequency section. This pin is high impedance in shutdown.
20
PGSU
Step-Up Power Ground. Connect all PG_ pins together and to GND with short traces as close to the IC as
possible.
21
LXSU
Step-Up Converter Switching Node. Connect to the inductor of the step-up converter. LXSU is high
impedance in shutdown.
22
PVSU
Power Output of the Step-Up DC-DC Converter. Connect the output filter capacitor from PVSU to PGSU.
PVSU can also power other converter channels. Connect PVSU to PV at the IC.
23
24
25
26
27
AUX2 Controller Feedback Input.
This pin is high impedance in
shutdown.
FB2
INDL2
DL2
MAX1584 (AUX2 step-up): The FB2 feedback threshold is 1.25V.
Connect a resistive voltage-divider from the output voltage to FB2 to
GND to set the output voltage.
AUX2 Controller Compensation Node. Connect a series resistor-capacitor from CC2 to GND to
compensate the control loop. CC2 is actively driven to GND in shutdown and thermal limit. See the AUX
Compensation section.
CC2
PV
MAX1585 (AUX2 inverter): The FB2 feedback threshold is 0V.
Connect a resistive voltage-divider from the output voltage to FB2 to
REF to set the output voltage.
Voltage Input for the AUX2 Gate
Driver. The voltage at INDL2 sets
the high gate-drive voltage.
MAX1585 (AUX2 inverter): Connect INDL2 to the external P channel
MOSFET source (typically the battery) to ensure the P channel is
completely off when D2 swings high.
MAX1584 (AUX2 step-up): Connect INDL2 to PVSU for optimum
N-channel gate drive.
IC Power Input. Connect PVSU and PV together.
AUX2 Controller Gate-Drive
Output. DL2 drives between
INDL2 and GND.
MAX1585: DL2 drives a PFET in an inverter configuration. In
shutdown, overload, and thermal limit, DL2 is driven high.
MAX1584: DL2 drives an N-channel FET in a boost/flyback
configuration. In shutdown, overload, and thermal limit, DL2 is driven
low.
______________________________________________________________________________________
11
MAX1584/MAX1585
Pin Description (continued)
5-Channel Slim DSC Power Supplies
MAX1584/MAX1585
Pin Description (continued)
PIN
NAME
28
DL3
AUX3 Step-Down Controller Gate-Drive Output. Connect to the gate of a P-channel MOSFET. DL3 swings
from GND to PVSU and supplies up to 500mA. DL3 is driven to PVSU in shutdown and thermal limit.
29
DL1
AUX1 Step-Up Controller Gate-Drive Output. Connect to the gate of an N-channel MOSFET. DL1 swings
from GND to PVSU and supplies up to 500mA. DL1 is driven to GND in shutdown and thermal limit.
30
GND
Analog Ground. Connect to all PG_ pins as close to the IC as possible.
31
CC3
AUX3 Step-Down Controller Compensation Node. Connect a series resistor-capacitor from CC3 to FB3 to
compensate the converter control loop. This pin is actively driven to GND in shutdown, overload, and
thermal limit. See the AUX Compensation section.
32
FB3
PWM Step-Up Controller 3 Feedback Input. Connect a resistive voltage-divider from the output voltage to
FB3 to GND to set the output voltage. The FB3 feedback threshold is 1.25V. This pin is high impedance in
shutdown.
EP
Exposed Underside Metal Pad. This pad must be soldered to the PC board to achieve package thermal
and mechanical ratings. There is no internal metal or bond wire physically connecting the exposed pad to
the GND pin(s). Connecting the exposed pad to ground does not remove the requirement for a good
ground connection to the appropriate IC pins.
PAD
FUNCTION
Detailed Description
The MAX1584/MAX1585 are complete power-conversion ICs for slim digital still cameras. They can accept
input from a variety of sources, including single-cell Li+
batteries and 2-cell alkaline or NiMH batteries, as well
as systems designed to accept both battery types. The
MAX1584/MAX1585 include five DC-DC converter
channels to generate all required voltages (Figure 2
shows a functional diagram):
• Synchronous-rectified step-up DC-DC converter with
on-chip MOSFETs—Typically supplies 3.3V for main
system power or 5V to power other DC-DC converters for boost-buck designs.
• Synchronous-rectified step-down DC-DC converter
with on-chip MOSFETs—Typically supplies 1.8V for
the DSP core. Powering the step-down from the
step-up output provides efficient (up to 90%) boostbuck functionality that supplies a regulated output
when the battery voltage is above or below the output voltage. The step-down can also be powered
from the battery if there is sufficient headroom.
• AUX1 step-up controller—Typically used for 15V to
bias one or more of the LCD, CCD, and LED backlights.
12
• AUX2 step-up controller (MAX1584)—Typically supplies remaining bias voltages with either a multi-output flyback transformer or a boost converter with
charge-pump inverter. Alternately, can power white
LEDs for LCD backlighting.
• AUX2 inverter controller (MAX1585)—Typically supplies negative CCD bias when high current is needed for large pixel-count CCDs.
• AUX3 step-down controller—Typically steps 5V generated at PVSU down to 3.3V for system logic in
boost-buck designs.
Step-Up DC-DC Converter
The step-up DC-DC switching converter is typically used
to generate a 5V output voltage from a 1.5V to 4.5V battery input, but any voltage from VIN to 5V can be set. An
internal NFET switch and a PFET synchronous rectifier
allow conversion efficiencies as high as 95%. Under
moderate to heavy loading, the converter operates in a
low-noise PWM mode with constant frequency and modulated pulse width. Switching harmonics generated by
fixed-frequency operation are consistent and easily filtered. Efficiency is enhanced under light ( L / [(REQ / 2)2] = 10µH / 0.25 = 40µF
Choose COUT = 47µF:
C4 = (VIN / VRAMP)(1 / [2π x R14 x fC])
= (5 / 1.25)(1/ [2π x 30.1k x 50kHz) = 423pF
Choose C4 = 470pF.
Cancel one pole of the complex pole pair by placing
the R4 C4 zero at 0.75 f0. The complex pole pair is at
the following:
f0 = 1 / [2π(L x COUT)1/2]
= 1 / [2π(10µH x 47µF)1/2] = 7.345kHz
Choose R4 = 1 / (2π x C4 x 0.75 x f0)
= 1 / (2π x 470pF x 0.75 x 7.345kHz)
z
Choose R4 = 61.9kΩ (standard 1% value). Ensure that
R4 > 2 / gMEA = 14.8kΩ. If it is not greater, reselect
R14 and R15.
Cancel the second pole of the complex pole pair by
placing the R14 C20 zero at 1.25 x f0.
C20 = 1 / (2π x R14 x 1.25 x f0)
= 1 / (2π x 30.1k x 1.25 x 7.345kHz) = 576pF
Choose C20 = 560pF.
Roll off the gain below the switching frequency by placing a pole at fOSC / 2:
R22 = 1 / (2π x C20 [fOSC / 2])
= 1 / (2π x 560pF x 250kHz) = 1.137kΩ
Choose R22 = 1.2kΩ.
If the output filter capacitor has significant ESR, a zero
occurs at the following:
ZESR = 1 / (2π x COUT x RESR)
Use the R4 C22 pole to cancel the ESR zero:
C22 = COUT x RESR / R4
If C22 is calculated to be
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