Maxim MAX1605 30v internal switch lcd bias supply Datasheet

19-1666; Rev 1; 10/03
30V Internal Switch LCD Bias Supply
Features
♦ Adjustable Output Voltage up to 30V
♦ 20mA at 20V from a Single Li+ Battery
♦ 88% Efficiency
♦ Up to 500kHz Switching Frequency
♦ Selectable Inductor Current Limit
(125mA, 250mA, or 500mA)
♦ 18µA Operating Supply Current
♦ 0.1µA Shutdown Current
♦ Avaiable in Two Small Packages
6-Pin TDFN
6-Pin SOT23
Ordering Information
Applications
LCD Bias Generators
TEMP
RANGE
PART
Cellular/Cordless Phones
PINPACKAGE
SOT
MARK
Palmtop Computers
MAX1605EUT-T
-40°C to +85°C
6 SOT23-6
AAHP
Personal Digital Assistants (PDAs)
MAX1605ETT-T
-40°C to +85°C
6 TDFN
ABW
Organizers
Handy Terminals
Typical Operating Circuit
L1
10µH
VIN = 0.8V TO VOUT
Pin Configuration
TOP VIEW
SHDN 1
VCC = 2.4V TO 5.5V
6
FB
5
4
SHDN
1
LIM
VCC
2
LX
GND
3
LX
VCC
VCC 2
MAX1605
MAX1605
GND 3
LIM
FB
SOT23
SHDN
MAX1605
5
LIM
4
LX
FB
ON
OFF
6
VOUT = VIN TO 30V
TDFN
3mm ✕ 3mm
GND
________________________________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
1
MAX1605
General Description
The MAX1605 boost converter contains a 0.5A internal
switch in a tiny 6-pin SOT23 package. The IC operates
from a +2.4V to +5.5V supply voltage, but can boost
battery voltages as low as 0.8V up to 30V at the output.
The MAX1605 uses a unique control scheme providing
the highest efficiency over a wide range of load conditions. An internal 0.5A MOSFET reduces external component count, and a high switching frequency (up to
500kHz) allows for tiny surface-mount components. The
current limit can be set to 500mA, 250mA, or 125mA,
allowing the user to reduce the output ripple and component size in low-current applications.
Additional features include a low quiescent supply current and a shutdown mode to save power. The
MAX1605 is ideal for small LCD panels with low current
requirements, but can also be used in other applications. A MAX1605EVKIT evaluation kit (EV kit) is available to help speed up design time.
MAX1605
30V Internal Switch LCD Bias Supply
ABSOLUTE MAXIMUM RATINGS
VCC, FB, LIM, SHDN to GND....................................-0.3V to +6V
LX to GND ..............................................................-0.3V to +32V
Continuous Power Dissipation (TA = +70°C)
6-Pin SOT23 (derate 8.7mW/°C above +70°C) ...........696mW
6-Pin TDFN (derate 24.4mW/°C above +70°C) .........1951mW
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
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
(VCC = SHDN = 3.3V, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Supply Voltage
VCC
(Note 2)
2.4
5.5
V
Inductor Input Voltage Range
VIN
(Note 2)
0.8
VOUT
V
VCC falling, 50mV typical hysteresis
2.0
VCC Undervoltage Lockout
VUVLO
Quiescent Supply Current
ICC
Shutdown Supply Current
2.2
2.37
V
VFB = 1.3V
18
35
µA
SHDN = GND
0.1
1
µA
VCC Line Regulation
∆VLNR
VOUT = 18V, ILOAD = 1mA, VIN = 5V,
VCC = VLIM = 2.4V to 5.5V
0.1
%/V
VIN Line Regulation
∆VLNR
VOUT = 18V, ILOAD = 1mA,
VCC = VLIM = 5V, VIN = 2.4V to 12V
0.15
%/V
Load Regulation
∆VLDR
VOUT = 18V, VCC = VIN = VLIM = 5V,
ILOAD = 0mA to 20mA
0.1
%/mA
L1 = 100µH, VIN = 3.6V, ILOAD = 10mA
88
%
Efficiency
Feedback Set Point
VFB
Feedback Input Bias Current
IFB
1.225
VFB = 1.3V
1.25
1.275
V
5
100
nA
30.5
V
LX
LX Voltage Range
LX Switch Current Limit
LX On-Resistance
VLX
ILX(MAX)
RLX
LX Leakage Current
Maximum LX On-Time
Minimum LX Off-Time
2
LIM = VCC
0.40
0.50
0.56
LIM = floating
0.20
0.25
0.285
LIM = GND
0.10
0.125
0.15
VCC = 5V, ILX = 100mA
0.8
VCC = 3.3V, ILX = 100mA
Ω
1
2
2
µA
10
13
16
µs
VFB > 1.1V
0.8
1.0
1.2
VFB < 0.8V (soft-start)
3.9
5.0
6.0
VLX = 30.5V
tON
tOFF
A
_______________________________________________________________________________________
µs
30V Internal Switch LCD Bias Supply
(VCC = SHDN = 3.3V, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
CONTROL INPUTS
VIH
2.4V ≤ VCC ≤ 5.5V
SHDN Input Threshold
VIL
SHDN Input Bias Current
ISHDN
0.8 ×
VCC
0.2 ×
VCC
2.4V ≤ VCC ≤ 5.5V
VCC = 5.5V, V SHDN = 0 to 5.5V
-1
LIM Input Low Level
2.4V ≤ VCC ≤ 5.5V
LIM Input Float Level
2.4V ≤ VCC ≤ 5.5V,
ILIM = ±0.5µA
(VCC / 2) 0.2V
LIM Input High Level
2.4V ≤ VCC ≤ 5.5V
VCC
- 0.4V
LIM Input Bias Current
ILIM
SHDN = VCC, LIM = GND or VCC
1
µA
0.4
V
(VCC / 2)
+ 0.2V
V
V
-2
SHDN = GND
V
2
0.1
1
µA
ELECTRICAL CHARACTERISTICS
(VCC = SHDN = 3.3V, TA = -40°C to +85°C, unless otherwise noted.) (Note 1)
MIN
MAX
Supply Voltage
PARAMETER
SYMBOL
VCC
(Note 2)
2.4
5.5
V
Inductor Input Voltage Range
VIN
(Note 2)
0.8
VOUT
V
VCC falling, 50mV typical hysteresis
2.0
VCC Undervoltage Lockout
VUVLO
Quiescent Supply Current
ICC
Shutdown Supply Current
Feedback Set Point
VFB
Feedback Input Bias Current
IFB
CONDITIONS
UNITS
2.37
V
VFB = 1.3V
35
µA
SHDN = GND
1
µA
1.215
VFB = 1.3V
1.285
V
100
nA
30.5
V
LX
LX Voltage Range
VLX
LX Switch Current Limit
LX On-Resistance
ILX(MAX)
RLX
LX Leakage Current
Maximum LX On-Time
Minimum LX Off-Time
LIM = VCC
0.35
0.58
LIM = floating
0.18
0.30
LIM = GND
0.08
0.17
VCC = 3.3V, ILX = 100mA
2
Ω
VLX = 30.5V
2
µA
µs
tON
tOFF
A
9
17
VFB > 1.1V
0.75
1.25
VFB < 0.8V
3.8
6.0
µs
CONTROL INPUTS
VIH
2.4V ≤ VCC ≤ 5.5V
VIL
2.4V ≤ VCC ≤ 5.5V
SHDN Input Threshold
SHDN Input Bias Current
ISHDN
VCC = 5.5V, VSHDN = 0 to 5.5V
0.8 ×
VCC
0.2 ×
VCC
-1
1
V
µA
_______________________________________________________________________________________
3
MAX1605
ELECTRICAL CHARACTERISTICS (continued)
ELECTRICAL CHARACTERISTICS (continued)
(VCC = SHDN = 3.3V, TA = -40°C to +85°C, unless otherwise noted.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
LIM Input Low Level
2.4V ≤ VCC ≤ 5.5V
LIM Input Float Level
2.4V ≤ VCC ≤ 5.5V,
ILIM = ±0.5µA
(VCC / 2)
- 0.25V
LIM Input High Level
2.4V ≤ VCC ≤ 5.5V
VCC
- 0.4V
-2
LIM Input Bias Current
SHDN = VCC, LIM = GND or VCC
ILIM
MAX
UNITS
0.4
V
(VCC / 2)
+ 0.25V
V
V
2
SHDN = GND
µA
1
Note 1: All devices are 100% tested at TA = +25°C. All limits over the temperature range are guaranteed by design.
Note 2: The MAX1605 requires a supply voltage between +2.4V and +5.5V; however, the input voltage used to power the inductor
can vary from +0.8V to VOUT.
Typical Operating Characteristics
(VCC = 3.3V, VIN = 3.6V, L1 = 10µH, SHDN = LIM = VCC, VOUT(NOM) = 18V (Figure 3), TA = +25°C, unless otherwise noted.)
17.9
IOUT = 1mA
17.8
20.7
20.5
IOUT = 1mA
20.1
19.9
17.7
2.5
3.0
3.5
4.0
4.5
5.0
0
5.5
3
6
9
MAX1605 toc03
18.0
17.9
17.8
LIM = GND
(125mA)
17.7
LIM = OPEN
(250mA)
17.5
17.4
0
12
5
10
15
20
SUPPLY VOLTAGE (V)
INPUT VOLTAGE (V)
LOAD CURRENT (mA)
EFFICIENCY vs. SUPPLY VOLTAGE
(L1 = 10µH)
EFFICIENCY vs. INPUT VOLTAGE
(L1 = 10µH)
EFFICIENCY vs. LOAD CURRENT
(L1 = 10µH)
76
74
IOUT = 1mA
VIN80= 3.6V
ILIM = 500mA
72
IOUT = 1mA
60
50
VCC = 3.3V
ILIM = 500mA
2.5
3.0
3.5
4.0
4.5
SUPPLY VOLTAGE (V)
5.0
5.5
76
74
LIM = OPEN
(250mA)
72
70
68
LIM = VCC
(500mA)
LIM = GND
(125mA)
64
62
30
70
78
66
40
25
MAX1605 toc06
80
70
80
MAX1605 toc05
IOUT = 5mA
EFFICIENCY (%)
IOUT = 10mA
IOUT = 5mA
78
90
MAX1605 toc04
80
2.0
18.1
17.6
19.5
2.0
LIM = VCC
(500mA)
18.2
VCC = 3.3V
LIM = VCC
(500mA)
19.7
17.6
4
MAX1605 toc02
20.9
20.3
18.3
OUTPUT VOLTAGE (V)
IOUT = 5mA
IOUT = 5mA
21.1
18.4
EFFICIENCY (%)
OUTPUT VOLTAGE (V)
18.0
21.3
OUTPUT VOLTAGE (V)
VIN = 3.6V
LIM = VCC
(500mA)
18.1
21.5
MAX1605 toc01
18.2
OUTPUT VOLTAGE
vs. LOAD CURRENT
OUTPUT VOLTAGE vs. INPUT VOLTAGE
OUTPUT VOLTAGE vs. SUPPLY VOLTAGE
EFFICIENCY (%)
MAX1605
30V Internal Switch LCD Bias Supply
60
0
3
6
INPUT VOLTAGE (V)
9
12
0
5
10
15
LOAD CURRENT (mA)
_______________________________________________________________________________________
20
25
30V Internal Switch LCD Bias Supply
EFFICIENCY vs. LOAD CURRENT
(L1 = 100µH)
88
80
78
LIM = VCC
(500mA)
LIM = GND
5
10
15
20
100
0
25
5
10
15
20
25
LOAD CURRENT (mA)
LOAD CURRENT (mA)
CURRENT LIMIT vs. INPUT VOLTAGE
SUPPLY CURRENT
vs. SUPPLY VOLTAGE (NO-LOAD)
400
LIM = OPEN
300
200
20
0
3
6
9
15
10
2
3
4
5
0
5
10
15
20
25
LOAD CURRENT (mA)
SHUTDOWN WAVEFORM
MAX1605 toc15
IOUT
10mA/div
4V
10mA
18.1V
18.1V
17.9V
VOUT
100mV/div
A
2V/div
0
2V
2V
0
500mA
250mA
0
IL1
500mA/div
B
100mV/div
18V
17.9V
LIM = VCC
(500mA)
MAX1605 toc14
6V
18
1.0
0
1
MAX1605 toc13
4V
5.5
1.5
LOAD TRANSIENT
LINE TRANSIENT
5.0
LIM = OPEN
(250mA)
2.0
SUPPLY VOLTAGE (V)
INPUT VOLTAGE (V)
4.5
0.5
0
12
4.0
LIM = GND
(125mA)
2.5
0
100
3.5
SUPPLY CURRENT vs. LOAD CURRENT
5
LIM = GND
3.0
3.0
SUPPLY CURRENT (mA)
500
SUPPLY CURRENT (µA)
LIM = VCC
2.5
SUPPLY VOLTAGE (V)
25
MAX1605 toc10
600
2.0
MAX1605 toc11
0
LIM = OPEN
200
74
74
CURRENT LIMIT (mA)
LIM = VCC
(500mA)
76
300
VSHDN
2V/div
76
80
400
IL1
250mA/div
78
82
MAX1605 toc12
LIM = GND
(125mA)
82
LIM = GND
(125mA)
84
LIM = VCC
500
500mA
0
20V
VOUT
10V/div
84
EFFICIENCY (%)
EFFICIENCY (%)
LIM = OPEN
(250mA)
LIM = OPEN
(250mA)
CURRENT LIMIT (mA)
86
86
600
MAX1605 toc08
88
CURRENT LIMIT vs. SUPPLY VOLTAGE
90
MAX1605 toc07
90
MAX1605 toc09
EFFICIENCY vs. LOAD CURRENT
(L1 = 47µH)
10V
0
200µs/div
A: VIN = VCC = 2.4V TO 5.5V
B: VOUT = 18V, ROUT = 3.6kΩ
40µs/div
VOUT = 18V, IOUT = 1mA TO 10mA
VCC = 3.3V, VIN = 3.6V
200µs/div
VOUT = 18V, ROUT = 1.8kΩ
VCC = 3.3V, VIN = 3.6V
_______________________________________________________________________________________
5
MAX1605
Typical Operating Characteristics (continued)
(VCC = 3.3V, VIN = 3.6V, L1 = 10µH, SHDN = LIM = VCC, VOUT(NOM) = 18V (Figure 3), TA = +25°C, unless otherwise noted.)
30V Internal Switch LCD Bias Supply
MAX1605
Pin Description
PIN
NAME
FUNCTION
1
SHDN
2
VCC
IC Supply Voltage (+2.4V to +5.5V). Bypass VCC to GND with a 0.1µF or greater capacitor.
3
GND
Ground
4
LX
Inductor Connection. The drain of an internal 30V N-channel MOSFET. LX is high impedance in
shutdown.
5
LIM
Inductor Current Limit Selection. Connect LIM to VCC for 500mA, leave LIM floating for 250mA,
or connect LIM to GND for 125mA.
6
FB
Feedback Input. Connect to a resistive-divider network between the output (VOUT) and FB to set
the output voltage between VIN and 30V. The feedback threshold is 1.25V.
Active-Low Shutdown Input. A logic low shuts down the device and reduces the supply current
to 0.1µA. Connect SHDN to VCC for normal operation.
L1
10µH
VIN = 0.8V TO VOUT
VOUT = VIN TO 30V
LX
COUT
CFF
VCC = 2.4V TO 5.5V
CONTROL
LOGIC
N
VCC
LIM
CURRENT
LIMIT
R1
SHUTDOWN
LOGIC
SHDN
ON
FB
ERROR
AMPLIFIER
OFF
R2
1.25V
GND
MAX1605
Figure 1. Functional Diagram
Detailed Description
The MAX1605 compact, step-up DC-DC converter operates from a +2.4V to +5.5V supply. Consuming only
18µA of supply current, the device includes an internal
switching MOSFET with 1Ω on-resistance and selectable
current limit (Figure 1). During startup, the MAX1605
extends the minimum off-time, limiting initial surge current. The MAX1605 also features a shutdown mode.
6
Control Scheme
The MAX1605 features a minimum off-time, current-limited control scheme. The duty cycle is governed by a
pair of one-shots that set a minimum off-time and a
maximum on-time. The switching frequency can be up
to 500kHz and depends upon the load and input voltage. The peak current limit of the internal N-channel
MOSFET is pin selectable and may be set at 125mA,
250mA, or 500mA (Figure 2).
_______________________________________________________________________________________
30V Internal Switch LCD Bias Supply
VCC
(2.4V TO 5.5V)
VCC
VCC
MAX1605
LIM
VCC
MAX1605
NO CONNECTION
GND
IPEAK = 500mA
MAX1605
VCC
(2.4V TO 5.5V)
VCC
(2.4V TO 5.5V)
MAX1605
LIM
LIM
GND
GND
IPEAK = 250mA
IPEAK = 125mA
Figure 2. Setting the Peak Inductor Current Limit
Setting the Output Voltage (FB)
Separate/Same Power for L1 and VCC
Adjust the output voltage by connecting a voltagedivider from the output (VOUT) to FB (Figure 3). Select
R2 between 10kΩ to 200kΩ. Calculate R1 with the following equation:
Separate voltage sources can supply the inductor (VIN)
and the IC (VCC). This allows operation from low-voltage
batteries as well as high-voltage sources (0.8V to 30V)
because chip bias is provided by a logic supply (2.4V
to 5.5V), while the output power is sourced directly from
the battery to L1. Conversely, VIN and VCC can also be
supplied from one supply if it remains within V CC’s
operating limits (+2.4V to +5.5V).
R1 = R2 [(VOUT / VFB) – 1]
where VFB = 1.25V and VOUT may range from VIN to
30V. The input bias current of FB has a maximum value
of 100nA, which allows large-value resistors to be used.
For less than 1% error, the current through R2 should
be greater than 100 times the feedback input bias current (IFB).
Current Limit Select Pin (LIM)
The MAX1605 allows a selectable inductor current limit
of 125mA, 250mA, or 500mA (Figure 2). This allows
flexibility in designing for higher current applications or
for smaller, compact designs. The lower current limit
allows the use of a physically smaller inductor in spacesensitive, low-power applications. Connect LIM to VCC
for 500mA, leave floating for 250mA, or connect to
GND for 125mA.
Shutdown (SHDN)
Pull SHDN low to enter shutdown. During shutdown, the
supply current drops to 0.1µA and LX enters a highimpedance state. However, the output remains connected to the input through the inductor and output
rectifier, holding the output voltage to one diode drop
below VIN when the MAX1605 is shut down. The capacitance and load at OUT determine the rate at which
V OUT decays. SHDN can be pulled as high as 6V,
regardless of the input and output voltages.
L1
10µH
VIN = 0.8V TO VOUT
CIN
10µF
VCC = 2.4V TO 5.5V
D1
C1
0.1µF
VOUT = 18V
LX
VCC
R1
2.2MΩ
MAX1605
LIM
CFF
10pF
COUT
1µF
FB
R2
165kΩ
ON
OFF
SHDN
GND
Figure 3. Typical Application Circuit
_______________________________________________________________________________________
7
MAX1605
30V Internal Switch LCD Bias Supply
Design Procedure
Inductor Selection
Smaller inductance values typically offer smaller physical size for a given series resistance or saturation current. Circuits using larger inductance values may start
up at lower input voltages and exhibit less ripple, but
also provide reduced output power. This occurs when
the inductance is sufficiently large to prevent the maximum current limit from being reached before the maximum on-time expires. The inductor’s saturation current
rating should be greater than the peak switching current. However, it is generally acceptable to bias the
inductor into saturation by as much as 20%, although
this will slightly reduce efficiency.
Picking the Current Limit
The peak LX current limit (ILX(MAX)) required for the
application may be calculated from the following equation:
ILX(MAX) ≥
(
)
VOUT − VIN(MIN) × t OFF(MIN)
VOUT × IOUT(MAX)
+
VIN(MIN)
2×L
where tOFF(MIN) = 0.8µs, and VIN(MIN) is the minimum
voltage used to supply the inductor. The set current
limit must be greater than this calculated value. Select
the appropriate current limit by connecting LIM to VCC,
GND, or leaving it unconnected (see the Current Limit
Select Pin (LIM) section and Figure 2).
Diode Selection
The high maximum switching frequency of 500kHz
requires a high-speed rectifier. Schottky diodes, such as
the Motorola MBRS0530 or the Nihon EP05Q03L, are
recommended. To maintain high efficiency, the average
current rating of the Schottky diode should be greater
than the peak switching current. Choose a reverse
breakdown voltage greater than the output voltage.
Output Filter Capacitor
For most applications, use a small ceramic surfacemount output capacitor, 1µF or greater. For small
ceramic capacitors, the output ripple voltage is dominated by the capacitance value. If tantalum or electrolytic capacitors are used, the higher ESR increases
the output ripple voltage. Decreasing the ESR reduces
the output ripple voltage and the peak-to-peak transient
voltage. Surface-mount capacitors are generally preferred because they lack the inductance and resistance of their through-hole equivalents.
8
Input Bypass Capacitor
Two inputs, VCC and VIN, require bypass capacitors.
Bypass VCC with a 0.1µF ceramic capacitor as close to
the IC as possible. The input supplies high currents to
the inductor and requires local bulk bypassing close to
the inductor. A 10µF low-ESR surface-mount capacitor
is sufficient for most applications.
PC Board Layout and Grounding
Careful printed circuit layout is important for minimizing
ground bounce and noise. Keep the MAX1605’s
ground pin and the ground leads of the input and output capacitors less than 0.2in (5mm) apart. In addition,
keep all connections to FB and LX as short as possible.
In particular, when using external feedback resistors,
locate them as close to FB as possible. To minimize
output voltage ripple, and to maximize output power
and efficiency, use a ground plane and solder GND
directly to the ground plane. Refer to the
MAX1605EVKIT evaluation kit for a layout example.
Applications Information
Negative Voltage for LCD Bias
The MAX1605 can also generate a negative output by
adding a diode-capacitor charge-pump circuit (D1, D2,
and C3) to the LX pin as shown in Figure 4. Feedback
is still connected to the positive output, which is not
loaded, allowing a very small capacitor value at C4. For
best stability and lowest ripple, the time constant of the
R1-R2 series combination and C4 should be near or
less than that of C2 and the effective load resistance.
Output load regulation of the negative output is somewhat looser than with the standard positive output circuit, and may rise at very light loads due to coupling
through the capacitance of D2. If this is objectionable,
reduce the resistance of R1 and R2, while maintaining
their ratio, to effectively preload the output with a few
hundred microamps. This is why the R1-R2 values
shown in Figure 3 are about 10-times lower than typical
values used for a positive-output design. When loaded,
the negative output voltage will be slightly lower (closer
to ground by approximately a diode forward voltage)
than the inverse of the voltage on C4.
Output Disconnected in Shutdown
When the MAX1605 is shut down, the output remains
connected to the input (Figure 3), so the output voltage
falls to approximately V IN - 0.6V (the input voltage
minus a diode drop). For applications that require output isolation during shutdown, add an external PNP
transistor as shown in Figure 4. When the MAX1605 is
active, the voltage set at the transistor’s emitter
exceeds the input voltage, forcing the transistor into the
_______________________________________________________________________________________
30V Internal Switch LCD Bias Supply
VCC =
2.4V TO
5.5V
R3
1Ω
C3
0.1µF
D1*
D2*
C5
1µF
MAX1605
L1
10µH
VIN =
0.8V TO
VOUT
VNEG
-19V
C2
1µF
D3**
LX
VCC
C6
0.1µF
R1
240kΩ
MAX1605
LIM
C1
1000pF
C4
0.01µF
FB
R2
16.5kΩ
ON
OFF
SHDN
GND
*D1, D2 = CENTRAL SEMICONDUCTOR
CMPD7000 DUAL
**D3 = CENTRAL SEMICONDUCTOR
CMSD4448 (1N4148)
Figure 4. Negative Voltage for LCD Bias
saturation region. When shut down, the input voltage
exceeds the emitter voltage so the inactive transistor
provides high-impedance isolation between the input
and output. Efficiency will be slightly degraded due to
the PNP transistor saturation voltage and base current.
L1
10µH
VIN = 0.8V TO VOUT
VSET = 18.3V
(VOUT + 0.3V)
LX
VOUT = 18V
2N2907A
R1
MAX1605
LIM
TRANSISTOR COUNT: 2329
R3 = 180kΩ
VCC = 2.4V TO 5.5V
VCC
Chip Information
FB
R2
ON
SHDN
GND
OFF
Figure 5. Output Disconnected in Shutdown
_______________________________________________________________________________________
9
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
6LSOT.EPS
MAX1605
30V Internal Switch LCD Bias Supply
PACKAGE OUTLINE, SOT-23, 6L
21-0058
10
______________________________________________________________________________________
F
1
1
30V Internal Switch LCD Bias Supply
6, 8, &10L, QFN THIN.EPS
L
A
D
D2
A2
PIN 1 ID
1
N
1
C0.35
b
E
PIN 1
INDEX
AREA
[(N/2)-1] x e
REF.
E2
DETAIL A
e
k
A1
CL
CL
L
L
e
e
A
DALLAS
SEMICONDUCTOR
PROPRIETARY INFORMATION
TITLE:
PACKAGE OUTLINE, 6, 8 & 10L,
TDFN, EXPOSED PAD, 3x3x0.80 mm
NUMBER OF LEADS SHOWN ARE FOR REFERENCE ONLY
APPROVAL
DOCUMENT CONTROL NO.
21-0137
REV.
1
D
______________________________________________________________________________________
2
11
MAX1605
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
MAX1605
30V Internal Switch LCD Bias Supply
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
COMMON DIMENSIONS
SYMBOL
A
MIN.
MAX.
0.70
0.80
D
2.90
3.10
E
2.90
3.10
A1
0.00
0.05
L
k
0.20
0.40
0.25 MIN.
A2
0.20 REF.
PACKAGE VARIATIONS
PKG. CODE
N
D2
E2
e
JEDEC SPEC
b
T633-1
6
1.50–0.10
2.30–0.10
0.95 BSC
MO229 / WEEA
0.40–0.05
1.90 REF
T833-1
8
1.50–0.10
2.30–0.10
0.65 BSC
MO229 / WEEC
0.30–0.05
1.95 REF
T1033-1
10
1.50–0.10
2.30–0.10
0.50 BSC
MO229 / WEED-3
0.25–0.05
2.00 REF
[(N/2)-1] x e
DALLAS
SEMICONDUCTOR
PROPRIETARY INFORMATION
TITLE:
PACKAGE OUTLINE, 6, 8 & 10L,
TDFN, EXPOSED PAD, 3x3x0.80 mm
APPROVAL
DOCUMENT CONTROL NO.
21-0137
REV.
D
2
2
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.
12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2003 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.