MAXIM MAX1778EVKIT

19-2063; Rev 0; 6/01
MAX1778 Evaluation Kit
Features
♦ +2.7V to +5.5V Input Range
♦ Output Voltages
+8V, >200mA (Step-Up Switching Regulator)
+20V, >10mA (Positive Charge-Pump Regulator)
-5V, >20mA (Negative Charge-Pump Regulator)
+2.5V, >200mA (LDO Linear Regulator)
+4V, >150mA Peak (VCOM Buffer)
♦ All Outputs Are Adjustable with Resistors
♦ >91% Efficiency
♦ Internal MOSFET Switches
♦ <1µA (typ) IC Shutdown Current
♦ 1MHz Step-Up Switching Regulator Frequency
♦ 500kHz Charge-Pump Regulator Switching
Frequency
♦ Adjustable Fault-Trip Level
♦ Low-Profile External Components
♦ Built-In Transient Load Tester
♦ Surface-Mount Components
♦ Fully Assembled and Tested
Ordering Information
PART
TEMP. RANGE
MAX1778EVKIT
0°C to +70°C
IC PACKAGE
24 TSSOP
Component List
DESIGNATION
QTY
DESCRIPTION
DESIGNATION
QTY
C1, C16, C17,
C18, C21
5
3.3µF ±10%, 10V X7R ceramic
capacitors (1210)
Taiyo Yuden LMK325BJ335KD
C5, C7, C11,
C13, C25−C29
9
1µF ±10%, 16V X7R ceramic
capacitors (1206)
Murata GRM42-6X7R105K016
C2
1
0.47µF ±10%, 10V X7R ceramic
capacitor (0603)
Taiyo Yuden LMK107BJ474KA
C8
1
1000pF ±10%, 50V X7R
ceramic capacitor (0603)
Murata GRM39X7R102K050AD
C3, C14
2
0.01µF ±10%, 50V X7R ceramic
capacitors (0603)
Murata GRM39X7R103K050AD
C9
1
0.22µF ±10%, 10V X7R ceramic
capacitor (0603)
Taiyo Yuden LMK107BJ224KA
0
Not installed (0603)
4
0.1µF ±20%, 16V X7R ceramic
capacitors (0603)
Taiyo Yuden EMK107BJ104MA
C12, C20, C24
C4, C6, C10, C22
DESCRIPTION
________________________________________________________________ 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
Evaluates: MAX1778/MAX1880/MAX1881/MAX1882
General Description
The MAX1778 evaluation kit (EV kit) is a fully assembled
and tested surface-mount circuit board that contains a
step-up switching regulator, two charge-pump voltageregulator circuits, a VCOM buffer, and a low-drop out
linear regulator (LDO). The step-up switching circuit is
configured for a +8V output that provides up to 250mA
of current from a +3.0V supply. The EV kit can be powered from a +2.7V to +5.5V supply.
The positive charge-pump circuit is configured for a
+20V output that provides more than 10mA of current.
The negative charge-pump circuit is configured for a
-5V output and provides more than 20mA of current.
Power for both charge-pump inputs is provided from
the step-up switching regulator output.
The EV kit also features an LDO linear regulator circuit,
which is configured for a +2.5V output that provides
more than 200mA of current. Power for the LDO regulator circuit is provided from the input supply. The VCOM
buffer provides a +4V output and more than 150mA of
peak current. The step-up switching regulator output
provides power to the VCOM buffer.
The MAX1778 EV kit demonstrates low quiescent current and high efficiency (over 91%). High-frequency
operation (500kHz/1MHz) allows the use of tiny surfacemount components and fast transient response. The
MAX1778 TSSOP package (1.1mm max) with low-profile external components allows this circuit to be less
than 1.2mm in height. A built-in transient load tester
facilitates transient load tests. The MAX1778 EV kit can
also be used to evaluate the MAX1880, MAX1881, and
MAX1882 ICs.
MAX1778 Evaluation Kit
Evaluates: MAX1778/MAX1880/MAX1881/MAX1882
Component List (continued)
DESIGNATION
C19
D1
D2, D3, D4
2
QTY
1
1
3
PHONE
FAX
470pF ±5%, 50V COH ceramic
capacitor (0603)
Taiyo Yuden UMK107CH4715Z
Central
Semiconductor
516-435-1110
516-435-1824
Coilcraft
847-639-6400
847-639-1469
3A, 30V Schottky diode (M-flat)
Toshiba CMS02
Fairchild
408-822-2000
408-822-2102
IRC
512-992-7900
512-992-3377
200mA, 25V Schottky diodes
(SOT23)
Fairchild BAT54S
Murata
814-237-1431
814-238-0490
Taiyo Yuden
408-573-4150
408-573-4159
Toshiba
949-455-2000
949-859-3963
D5
1
L1
1
6.8µH inductor
Coilcraft LPO25061B-682
1
Q1
1
SUPPLIER
DESCRIPTION
200mA, 75V ultra-fast diode
(SOT23)
Fairchild MMBD4148
N1
Component Suppliers
30V, 11.5A, N-channel
MOSFET (SOT223)
Fairchild Semiconductor
NDT455N
40V, 600mA, NPN transistor
(SOT23)
Central Semiconductor
CMPT2222A
R1
1
274kΩ ±1% resistor (0805)
R2, R4, R6
3
49.9kΩ ±1% resistors (0805)
R3
1
750kΩ ±1% resistor (0805)
R5
1
200kΩ ±1% resistor (0805)
R7
1
24kΩ ±5% resistor (0805)
R8, R10, R12
3
100kΩ ±1% resistors (0805)
R9
1
1MΩ ±5% resistor (0805)
R11, R13, R16
0
Not installed (0805)
R14, R15
2
10kΩ ±1% resistors (0805)
R17
1
51Ω ±5% resistor (0805)
R18
1
1.0Ω ±1%, 1W resistor (2010)
IRC LRC-LR 2010-01-1R00-F
R19
1
1.5kΩ ±5% resistor (0805)
R20
1
10Ω ±5% resistor (0805)
R21
1
10kΩ ±5% resistor (0805)
U1
1
MAX1778EUG (24-pin TSSOP)
JU1
1
2-pin header
None
1
Shunt (JU1)
None
1
MAX1778 PC board
None
1
MAX1778 data sheet
None
1
MAX1778 EV kit data sheet
Note: Please indicate that you are using the MAX1778,
MAX1880, MAX1881, or MAX1882 when contacting these
component suppliers.
Quick Start
The MAX1778 EV kit is fully assembled and tested.
Follow these steps to verify board operation. Do not
turn on the power supply until all connections are
completed.
Output Verification
1) Verify that jumper JU1 (SHDN) does not have a
shunt across its pins.
2) Connect a voltmeter to the V1 pad.
3) Connect a +2.7V to +5.5V DC power supply to the
PIN pad. Connect the supply ground to the GND
pad.
4) Turn on the power supply, and verify that the main
output (V1) is +8V.
5) Verify that the negative charge-pump regulator output (VN) is -5V.
6) Verify that the positive charge-pump regulator output (VP) is +20V.
7) Verify that the LDO output (LDOOUT) is +2.5V.
8) Verify that the V COM buffer output (BUFOUT) is
+4V.
For instructions on selecting the feedback resistors for
other output voltages, see Evaluating Other Output
Voltages. The input voltage range is +2.7V to +5.5V
when selecting the output voltage.
Detailed Description
The MAX1778 evaluation kit step-up switching regulator
circuit can be configured for an output voltage up to
+13V. A built-in transient load tester (TRANS_LOAD,
CSEN) for the step-up switching regulator allows transient load tests up to 1A.
_______________________________________________________________________________________
MAX1778 Evaluation Kit
The EV kit’s LDO linear regulator circuit is configured
for a +2.5V output (LDOOUT) at more than 200mA of
current and can be reconfigured for other output voltages by replacing feedback resistors. When using an
external transistor (Q1) for the LDO, regulator power for
the LDO output is provided by PIN. When an external
transistor (Q1) is not used, power is provided by the
step-up switching regulator (V1). For even higher output current, the SOT23 NPN transistor (Q1) can be
replaced with a larger D-PAK device.
The VCOM buffer output (BUFOUT) is a scaled down
voltage of the step-up switching regulator (V1) and can
be reconfigured for other voltages by replacing the voltage-divider resistors (R10, R11). The step-up switching
regulator provides power to the VCOM buffer. A separate analog ground pad (GND) for the VCOM buffer output is provided to reduce noise coupling to the output.
The EV kit features an adjustable fault-trip level that can
be reconfigured for different fault-trip levels.
Unpopulated feedback-compensation PC board pads
are provided for the step-up switching regulator. The linear regulator can be configured for different voltages
and output currents.
The MAX1778 EV kit can also evaluate the MAX1880,
MAX1881, and MAX1882. Order the IC from the phone
number listed on page 1, and replace the MAX1778 with
the appropriate IC.
Jumper Selection Shutdown Mode
The MAX1778 EV kit features a shutdown mode that
reduces the MAX1778 quiescent current.
The 2-pin jumper (JU1) selects the MAX1778 shutdown
mode. Table 1 lists the selectable jumper options.
Output Voltage Selection and
Transient Load Test
Step-Up SwitchingRegulator Output Voltages
The MAX1778 EV kit’s step-up switching-regulator output is set to +8V by feedback resistors (R1, R2). To
generate output voltages other than +8V (up to +13V),
select different external voltage-divider resistors (R1,
R2). The ceramic capacitors (C17, C18, C21) are rated
Table 1. Jumper JU1 Functions
SHUNT
LOCATION
SHDN
PIN
None
Connected to PIN
through R8
Enabled
Connected to GND
Shutdown
Installed
MAX1778
OUTPUT
to +10V, so replace them with higher voltage-rated
capacitors for output voltages over 10V. Refer to the
Output Voltage Selection section in the MAX1778 data
sheet for instructions on selecting the resistors.
Positive Charge-Pump Output Voltages
The MAX1778 EV kit’s positive charge-pump regulator
output is set to +20V by feedback resistors (R3, R4). To
generate output voltages other than +20V (up to +35V),
select different external voltage-divider resistors (R3,
R4). Refer to the Output Voltage Selection section in the
MAX1778/MAX1880–MAX1885 data sheet for instructions on selecting the resistors. Check that the capacitor voltage rating is adequate for the configuration.
Negative Charge-Pump Output Voltages
The MAX1778 EV kit’s negative charge-pump regulator
output is set to -5V by feedback resistors (R5, R6). To
generate output voltages other than -5V (down to -11V),
select different external voltage-divider resistors (R5,
R6). Refer to the Output Voltage Selection section in the
MAX1778/MAX1880–MAX1885 data sheet for instructions on selecting the resistors.
LDO Regulator Output Voltages
The MAX1778 EV kit’s LDO linear regulator output is set
to +2.5V by feedback resistors (R14, R15). To generate
output voltages other than +2.5V (+1.25V to V PIN
-300mV), select different external voltage-divider resistors (R14, R15). Refer to the Output Voltage Selection
section in the MAX1778 data sheet for instructions on
selecting the resistors. The power dissipation of the
NPN transistor (Q1, 350mW) must not be exceeded. If
a larger transistor is required, a “DPAK” surface-mount
case may be used to replace Q1 (MJD31, On
Semiconductor, or similar recommended). Refer to the
External Pass Transistor section in the MAX1778/
MAX1880–MAX1885 data sheet for instructions on
selecting a transistor.
VCOM Buffer Output Voltages
The MAX1778 EV kit’s VCOM buffer output (BUFOUT) is
configured to one half of V1’s output voltage (i.e., 0.5 ✕
8V = +4V) by using the MAX1778 IC’s internal 0.5 volt-
_______________________________________________________________________________________
3
Evaluates: MAX1778/MAX1880/MAX1881/MAX1882
The positive charge-pump circuit can be reconfigured
to provide up to +35V by changing feedback resistors,
provided that the step-up switching regulator (V1) has
been changed to a higher voltage. The negative
charge-pump circuit can also be reconfigured to provide up to -11V by changing feedback resistors, provided that the step-up switching regulator (V1) has
been adjusted to a higher voltage.
Evaluates: MAX1778/MAX1880/MAX1881/MAX1882
MAX1778 Evaluation Kit
age divider. Select different external voltage-divider resistors (R10, R11) to generate output voltages other than +4V
(+1.2V to +(VSUPB - 1.2V)). Refer to the Output Voltage
Selection section in the MAX1778/MAX1880–MAX1885
data sheet for instructions on selecting the resistors. The
VCOM buffer has a separate analog ground pad (GND)
next to the VCOM buffer output (BUFOUT) to reduce any
noise coupling.
Transient Load Tester
The MAX1778 EV kit features a built-in transient load
tester for the step-up switching regulator. Connect a
square-wave function generator (50Ω output) to the
TRANS_LOAD and GND pads. Set the frequency and
duty cycle as required. Note that varying the function
generator output voltage (2.0V typ to 10V max) will vary
the gate drive and thus will vary the amount of load
connected to V1. Set the low and high voltage of the
square-wave output according to the desired low- and
high-load currents. Load currents can be calculated by
measuring the voltage at the CSEN pad (across R18,
1Ω) and GND. Divide the measured voltage by 1Ω to
obtain the actual load current.
Faults and Maximizing
Transient Performance
Maximizing Transient Performance
The MAX1778 EV kit features several surface-mount,
unpopulated PC board pads for installing feedback
compensation components (R7, C19, C20). To maximize the transient load performance, remove capacitor
C8, connect the INTG pin (pin 2) to the REF pin (pin 9)
of IC U1, and remove resistor R7 and capacitor C19.
Refer to the Feedback Compensation section in the
MAX1778/MAX1880–MAX1885 data sheet for instructions on selecting other resistors and capacitors.
Evaluating Other ICs and
Different Linear Regulator
Configurations
Evaluating a MAX1880,
MAX1881, or MAX1882
The MAX1778 EV kit can be reconfigured for evaluating
the MAX1880, MAX1881, and MAX1882 ICs. U1
(MAX1778) must be removed and replaced with the
new IC (24-pin TSSOP package). The linear regulator
will not function when evaluating a MAX1880 or
MAX1882. Refer to the MAX1778/MAX1880–MAX1885
IC data sheet for information on the various step-up
switching frequency and LDO features.
Fault-Trip Level
The MAX1778 EV kit’s fault-trip level for the step-up
switching regulator and the positive charge pump is configured for a +1.1V (0.67 ✕ VREF to 0.87 ✕ VREF) fault-trip
level. To reconfigure the EV kit for other fault-trip levels
(+0.84V to +1.09V), select different external voltagedivider resistors (R12, R13). Refer to the Fault-Trip Level
(FLTSET) section in the MAX1778/MAX1880–MAX1885
data sheet for instructions on selecting the resistors.
Linear Regulator Voltages
The MAX1778 EV kit can be reconfigured for evaluating
other linear regulator voltages and currents. Several
components must be replaced to obtain higher voltages or currents. Table 2 lists the components to
replace.
Table 2. Component List for Evaluating Other Linear Regulators
4
DESIGNATOR
CASE 1
CASE 2
CASE 3
CASE 4
LDO Output Voltage
(LDOOUT)
+7.6V
(V1 set to 8V)
+9V to +12.4V
(V1 set to 13V)
+3.3V
+2.5V
LDO Output Current
(LDOOUT)
40mA
40mA
300mA to 500mA
200mA
Q1 (external NPN)
Not installed
Not installed
D-PAK (MJD31)
SOT23 (2N2222A)
C3
Not installed
Not installed
0.01µF
0.01µF
C14
Not installed
Not installed
0.01µF
0.01µF
C27
3.3µF
2.2µF
1.0µF
1.0µF
C29
Not installed
Not installed
1.0µF
1.0µF
10kΩ
R14
10kΩ
10kΩ
10kΩ
R15
51.1kΩ
60kΩ to 89kΩ
16.5kΩ
10kΩ
R16
0Ω
0Ω
Not installed
Not installed
R19
13kΩ
13kΩ
4.02kΩ
3.01kΩ
_______________________________________________________________________________________
_______________________________________________________________________________________
R
1 L
2
D3
R5
200kΩ
1%
C24
OPEN
C1
3.3µF
10V
PIN
3
V1
R8
100kΩ
1%
R6
49.9kΩ
1%
C6
0.1µF
BUFOUT
R10
100kΩ
1% V1
C2
0.47µF
C16
3.3µF
10V
REF
JU1
C9
0.22µF
C26
1.0µF
16V
C25
1.0µF
R11
OPEN
C8
1000pF
R20
10Ω
12
9
11
18
7
5
6
4
17
2
23
3
SHDN
REF
FBN
DRVN
BUFOUT
BUF-
SUPB
BUF+
SUPN
INTG
TGND
IN
MAX1778
U1
L1
6.8µH
SUPL
LDOOUT
GND
FBP
FLTSET
FBL
RDY
DRVP
SUPP
PGND
FB
LX
13
14
8
10
16
15
24
20
19
21
1
22
C28
1.0µF
16V
C27
1.0µF
16V
R4
49.9kΩ
1%
REF
FBLDO
PIN
R2
49.9kΩ
1%
R1
274kΩ
1%
RDY
R13
OPEN
R9
1MΩ
V1
D1
V1
C4
0.1µF
C10
0.1µF
R3
750kΩ
1%
R12
100kΩ
1%
C12
OPEN
C19
470pF
R7
24kΩ
C17
3.3µF
10V
3
3
R19
1.5kΩ
C20
OPEN
C18
3.3µF
10V
D2
D4
2
2
L 1
R
L 1
R
C21
3.3µF
10V
V1
C22
0.1µF
C5
1.0µF
CSEN
N1
4
1
V1
R18
1.0Ω
1%
3
2
FBLDO
1
R14
10kΩ
1%
L
2 R
1
C3
0.01µF
C11
1.0µF
R 2
L
R21
10kΩ
C14
0.01µF
R15
10kΩ
1%
R16
OPEN
3
D5
V1
+8V
Q1
3
GND
VP
+20V
GND
C29
1.0µF
16V
C13
1.0µF
16V
TRANS_LOAD
R17
51Ω
GND
LDOOUT
+2.5V
PIN
Evaluates: MAX1778/MAX1880/MAX1881/MAX1882
NOTE: REMOVE C8, R7, AND C19, AND SHORT U1-2 (INTG) TO
U1-9 (REF) FOR IMPROVED TRANSIENT RESPONSE.
C7
1.0µF
VN
-5V
GND
GND
PIN
MAX1778 Evaluation Kit
Figure 1. MAX1778 EV Kit Schematic
5
Evaluates: MAX1778/MAX1880/MAX1881/MAX1882
MAX1778 Evaluation Kit
1.0"
1.0"
Figure 2. MAX1778 EV Kit Component Placement Guide—
Component Side
Figure 3. MAX1778 EV Kit PC Board Layout—Component Side
1.0"
Figure 4. MAX1778 EV Kit PC Board Layout—Solder Side
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.
6 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2001 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.