MAXIM MAX1959ETP

19-2659; Rev 0; 10/02
KIT
ATION
EVALU
E
L
B
A
IL
AVA
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
The MAX1958/MAX1959 power amplifier (PA) powermanagement ICs (PMICs) integrate an 800mA, dynamically adjustable step-down converter, a 5mA Rail-toRail® operational amplifier (op amp), and a precision
temperature sensor to power a heterojunction bipolar
transistor (HBT) PA in W-CDMA and N-CDMA cell
phones.
The high-efficiency, pulse-width modulated (PWM), DCto-DC buck converter is optimized to provide a guaranteed output current of 800mA. The output voltage is
dynamically controlled to produce any fixed-output voltage in the range of 0.75V to 3.4V (MAX1958) or 1V to
3.6V (MAX1959), with settling time less than 30µs for a
full-scale change in voltage and current. The 1MHz PWM
switching frequency allows the use of small external
components while pulse-skip mode reduces quiescent
current to 190µA with light loads. The converter utilizes a
low on-resistance internal MOSFET switch and synchronous rectifier to maximize efficiency and minimize
external component count. The 100% duty-cycle operation allows for an IC dropout voltage of only 130mV (typ)
at 600mA load.
The micropower op amp is used to provide bias to the
HBT PA to maximize efficiency. The amplifier features
active discharge in shutdown for full PA bias control. It
has 5mA rail-to-rail drive capability, 800kHz gain-bandwidth product, and 120dB open-loop voltage gain.
The precision temperature sensor measures temperatures between -40°C to +125°C, with linear temperature-to-voltage analog output characteristics.
The MAX1958/MAX1959 are available in a 20-pin 5mm ✕
5mm thin QFN package (0.8mm max height).
Features
♦ Step-Down Converter
Dynamically Adjustable Output Voltage from
0.75V to 3.4V (MAX1958)
Dynamically Adjustable Output Voltage from
1V to 3.6V (MAX1959)
800mA Guaranteed Output Current
130mV IC Dropout at 600mA Load
Low Quiescent Current
190µA (typ) in Skip Mode (MAX1958)
3mA (typ) in PWM Mode
0.1µA (typ) in Shutdown Mode
1MHz Fixed-Frequency PWM operation
16% to 100% Duty-Cycle Operation
No External Schottky Diode Required
Soft-Start
♦ Operational Amplifier
5mA Rail-to-Rail Output
Active Discharge in Shutdown
800kHz Gain-Bandwidth Product
120dB Open-Loop Voltage Gain (RL = 100kΩ)
♦ Temperature Sensor
Accurate Sensor -11.7mV/°C Slope
-40°C to +125°C-Rated Temperature Range
♦ 20-Pin Thin QFN (5mm ✕ 5mm), 0.8mm Height (max)
Ordering Information
TEMP RANGE
PIN-PACKAGE
MAX1958ETP
PART
-40°C to +85°C
20 Thin QFN-EP*
MAX1959ETP
-40°C to +85°C
20 Thin QFN-EP
*EP = Exposed paddle.
IN-
IN+
VCC
SHDN1
INP
18
17
16
TOP VIEW
19
Applications
20
Pin Configuration
W-CDMA and N-CDMA Cellular Phones
Rail-to-Rail is a registered trademark of Nippon Motorola, Ltd.
1
15
PWM
2
14
INP
AGND
3
13
IN
TOUT
4
REF
5
7
8
9
10
ADJ
SHDN3
OUT
6
MAX1958/
MAX1959
AGND
Typical Operating Circuit and Functional Diagram appear at
end of data sheet.
AOUT
SHDN2
COMP
Wireless PDAs and Modems
12
LX
11
PGND
THIN QFN
5mm x 5mm
________________________________________________________________ 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
MAX1958/MAX1959
General Description
MAX1958/MAX1959
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
ABSOLUTE MAXIMUM RATINGS
IN, INP, OUT, ADJ, SHDN1, SHDN2,
SHDN3, PWM, VCC to PGND ...................................-0.3V to +6V
AGND to PGND .....................................................-0.3V to +0.3V
COMP, REF to AGND ....................................-0.3 to (VIN + 0.3V)
IN+, IN-, AOUT, TOUT to AGND ................-0.3 to (VVCC + 0.3V)
LX Current (Note 1).............................................................±1.6A
Output Short-Circuit Duration.....................................Continuous
Continuous Power Dissipation (TA = +70°C)
20-Pin Thin QFN 5mm x 5mm
(derate 20.8mW/°C above +70°C) .............................1670mW
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: LX has internal clamp diodes to PGND and INP. Applications that forward bias these diodes should take care not to exceed
the IC’s package 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 (STEP-DOWN CONVERTER)
(VINP = VIN = VVCC = V SHDN1 = 3.6V, VPWM = VPGND = VAGND = V SHDN2 = V SHDN3 = 0, VADJ = 1.25V, COMP = IN- = IN+ = AOUT
= TOUT = unconnected, CREF = 0.1µF, TA = 0°C to +85°C, VOUT for MAX1958 = 2.2V, VOUT for MAX1959 = 1.7V, unless otherwise
noted. Typical values are at TA = +25°C.)
PARAMETER
CONDITIONS
Supply Voltage Range
Undervoltage Lockout Threshold
Quiescent Current
MIN
Rising or falling, hysteresis is 1%
2.20
Shutdown Supply Current
MAX
UNITS
5.5
V
V
2.35
2.55
MAX1958, PWM = AGND
190
300
MAX1959, PWM = AGND
280
450
VPWM = VIN
Quiescent Current in Dropout
TYP
2.6
3
µA
mA
MAX1958
295
550
MAX1959
330
600
V SHDN1 = 0
0.1
6
µA
µA
ERROR AMPLIFIER
OUT Voltage Accuracy
(MAX1958)
OUT Voltage Accuracy
(MAX1959)
OUT Input Current (MAX1958)
OUT Input Current (MAX1959)
VADJ = 1.932V, ILOAD = 0 to 600mA, VPWM = VIN = 3.8V
3.38
3.40
3.42
VADJ = 0.426V, ILOAD = 0 to 30mA, VPWM = 0
0.739
0.750
0.761
VADJ = 0.426V, ILOAD = 0 to 30mA, VPWM = VIN = 4.2V
0.739
0.750
0.761
VADJ = 2.2V, ILOAD = 0 to 600mA, VPWM = VIN = 4V
3.58
3.60
3.62
VADJ = 0.9V, ILOAD = 0 to 30mA, VPWM = 0
0.985
1.00
1.015
VADJ = 0.9V, ILOAD = 0 to 30mA, VPWM = VIN = 4.2V
0.985
1.00
1.015
VOUT = 0.75V
2
4
6
VOUT = 3.4V
11
17
25
VOUT = 1V
2.5
4.0
6.5
VOUT = 3.6V
10
16
23
V
V
µA
µA
ADJ Input Current (MAX1958)
VADJ = 0.426V to 1.932V
-150
+1
+150
nA
ADJ Input Current (MAX1959)
VADJ = 0.9V to 2.2V
-150
+1
+150
nA
Positive COMP Output Current
(MAX1958)
VADJ = 1V, VOUT = 1.5V, VCOMP = 1.25V
-27
-14
-7
µA
Positive COMP Output Current
(MAX1959)
VADJ = 1V, VOUT = 1V, VCOMP = 1.25V
-27
-14
-7
µA
2
_______________________________________________________________________________________
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
(VINP = VIN = VVCC = V SHDN1 = 3.6V, VPWM = VPGND = VAGND = V SHDN2 = V SHDN3 = 0, VADJ = 1.25V, COMP = IN- = IN+ = AOUT
= TOUT = unconnected, CREF = 0.1µF, TA = 0°C to +85°C, VOUT for MAX1958 = 2.2V, VOUT for MAX1959 = 1.7V, unless otherwise
noted. Typical values are at TA = +25°C.)
PARAMETER
Negative COMP Output Current
(MAX1958)
Negative COMP Output Current
(MAX1959)
CONDITIONS
MIN
TYP
MAX
UNITS
VADJ = 1V, VOUT = 2V, VCOMP = 1.25V
7
14
27
µA
VADJ = 1V, VOUT = 1.4V, VCOMP = 1.25V
7
14
27
µA
1.225
1.250
1.275
V
2.50
6.25
mV
1.00
1.10
V
mV/V
REFERENCE
REF Output Voltage
REF Load Regulation
10µA < IREF < 100µA
Undervoltage Lockout Threshold
Rising or falling, 1% hysteresis
Supply Rejection
2.6V < VIN < 5.5V
0.07
1.7
0.85
CONTROLLER
P-Channel On-Resistance
N-Channel On-Resistance
ILX = 180mA, VIN = 3.6V
0.21
0.40
ILX = 180mA, VIN = 2.6V
0.25
0.5
ILX = 180mA, VIN = 3.6V
0.18
0.30
ILX = 180mA, VIN = 2.6V
0.21
0.35
Current-Sense Transresistance
0.5
P-Channel Current-Limit
Threshold
P-Channel Pulse-Skipping
Current Threshold
VPWM = 0
N-Channel Current-Limit
Threshold
VPWM = VIN
N-Channel Zero-Crossing
Comparator
VPWM = 0
LX Leakage Current
VIN = 5.5V
LX RMS Current
(Note 1)
Maximum Duty Cycle
Minimum Duty Cycle
Thermal-Shutdown Threshold
Ω
V/A
1.1
1.37
1.6
A
0.12
0.15
0.17
A
-20.0
-0.5
A
20
mA
+0.1
+20.0
1.0
100
0
VPWM = VIN = 4.2V
16
0.85
Hysteresis = +15°C
µA
A
%
VPWM = 0
Oscillator Frequency
Ω
1.00
1.15
%
MHz
°C
160
LOGIC INPUTS (PWM, SHDN1)
Logic Input High
2.6 V < VIN < 5.5 V
Logic Input Low
2.6 V < VIN < 5.5 V
Logic Input Current
VIN = 5.5V
1.6
V
0.1
0.6
V
1
µA
_______________________________________________________________________________________
3
MAX1958/MAX1959
ELECTRICAL CHARACTERISTICS (STEP-DOWN CONVERTER) (continued)
MAX1958/MAX1959
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
ELECTRICAL CHARACTERISTICS (OP AMP)
(VINP = VIN = VVCC = V SHDN2 = 2.7V, V AOUT = VVCC/2, RL = ∞ connected from AOUT to VVCC/2, VPGND = VAGND = V SHDN1 =
V SHDN3 = VPWM = VADJ = 0, OUT = LX = TOUT = REF = COMP = unconnected, VCM = 0, TA = 0°C to +85°C, unless otherwise
noted. Typical values are at TA = +25°C.)
PARAMETER
CONDITIONS
Supply Voltage Range
Supply Current
MIN
TYP
2.6
MAX
UNITS
5.5
V
VVCC = 2.6V
320
800
VVCC = 5V
375
900
V SHDN2 = 0, VVCC = 5.5V
0.1
2.0
µA
Input Offset Voltage
VAGND - 0.1V ≤ VCM ≤ VVCC + 0.1V
±0.4
±3.0
mV
Input Bias Current
VAGND - 0.1V ≤ VCM ≤ VVCC + 0.1V
±10
±100
nA
Input Offset Current
VAGND - 0.1V ≤ VCM ≤ VVCC + 0.1V
±1
±10
Input Resistance
VIN- - VIN+ ≤ 10mV
4
Input Common-Mode Voltage
Range, VCM
VVCC +
0.1
-0.1
nA
MΩ
V
Common-Mode Rejection Ratio,
CMRR
VAGND - 0.1V ≤ VCM ≤ VVCC + 0.1V
60
80
dB
Power-Supply Rejection Ratio,
PSRR
2.6V < VVCC < 5.5V
70
90
dB
Large-Signal Voltage Gain, AVOL
VAGND + 0.05V ≤ VAOUT ≤
VVCC - 0.05V
RL = 100kΩ
VAGND + 0.20V ≤ VAOUT ≤
VVCC - 0.20V
RL = 2kΩ
Output Voltage Swing High, VOH
VVCC -VVOH
Output Voltage Swing Low, VOL
VVOL- VAGND
Output Short-Circuit Current
120
dB
85
110
RL = 100kΩ
1
RL = 2kΩ
35
RL = 100kΩ
1
RL = 2kΩ
30
Sourcing, VVCC = 5V
11
Sinking, VVCC = 5V
30
SHDN2 Logic Low
2.6V < VVCC < 5.5V
SHDN2 Logic High
2.6V < VVCC < 5.5V
SHDN2 Input Current
0 < V SHDN2 < VVCC
90
90
mV
mV
mA
0.3 x
VVCC
0.7 x
VVCC
V
V
±0.5
±120
nA
Gain Bandwidth Product, GBW
1
MHz
Phase Margin, φM
70
Degrees
Gain Margin, GM
20
dB
Slew Rate, SR
0.4
V/µs
nV/√Hz
Input Voltage Noise Density
f = 10kHz
52
Input Current Noise Density
f = 10kHz
0.1
Capacitive-Load Stability
AVCL = 1V/V (Note 2)
pA/√Hz
470
pF
Shutdown Delay Time
3
µs
Enable Delay Time
4
µs
4
_______________________________________________________________________________________
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
(VINP = VIN = VVCC = V SHDN2 = 2.7V, V AOUT = VVCC/2, RL = ∞ connected from AOUT to VVCC/2, VPGND = VAGND = V SHDN1 =
V SHDN3 = VPWM = VADJ = 0, OUT = LX = TOUT = REF = COMP = unconnected, VCM = 0, TA = 0°C to +85°C, unless otherwise
noted. Typical values are at TA = +25°C.)
PARAMETER
CONDITIONS
MIN
Power-On Time
Input Capacitance
TYP
MAX
UNITS
4
µs
2.5
pF
0.01
%
µs
Total Harmonic Distortion
f =10kHz, VAOUT = 2VP-P, AVCL =1, VVCC = 5V,
RAOUT = 100kΩ to VVCC/2
Settling Time to 0.01%
∆VAOUT = 4V step, VVCC = 5V, AVCL = 1
10
Active Discharge Output
Impedance
V SHDN2 = 0, IAOUT = 1mA
100
500
Ω
ELECTRICAL CHARACTERISTICS (TEMPERATURE SENSOR)
(VINP = VIN = VVCC = V SHDN3 = 2.7V, VAGND = VPGND = VPWM = V SHDN1 = V SHDN2 = VADJ = 0, IN- = IN+ = AOUT = COMP = LX =
OUT = REF = unconnected, CTOUT = 0.01µF (min), TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.)
PARAMETER
Temperature Sensor Error
(Note 3)
CONDITIONS
MIN
TYP
MAX
TA = 0°C (Note 2)
-3.5
+3.5
TA = +25°C (Note 2)
-2.5
+2.5
TA = +85°C
-2.5
+2.5
Output Voltage at +27°C
Sensor Gain (Note 4)
Load Regulation
0 ≤ ILOAD ≤ 15µA
Line Regulation
2.6V ≤ VVCC ≤ 5.5V
Quiescent Current
2.6V ≤ VVCC ≤ 5.5V
SHDN3 Logic High Voltage
2.6V < VVCC < 5.5V
SHDN3 Logic Low Voltage
2.6V < VVCC < 5.5V
SHDN3 Current
VVCC = 5.5V
°C
1.56
V
-11.64
mV/°C
±0.4
Nonlinearity
UNITS
10
%
-5
mV
-2.3
mV/V
18
µA
1.6
V
0.1
0.6
V
1.0
µA
_______________________________________________________________________________________
5
MAX1958/MAX1959
ELECTRICAL CHARACTERISTICS (OP AMP) (continued)
MAX1958/MAX1959
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
ELECTRICAL CHARACTERISTICS (STEP-DOWN CONVERTER)
(VINP = VIN = VVCC = V SHDN1 = 3.6V, VPWM = VPGND = VAGND = V SHDN2 = V SHDN3 = 0, VADJ = 1.25V, COMP = IN- = IN+ =
AOUT = TOUT = unconnected, CREF = 0.1µF, TA = -40°C to +85°C, VOUT for MAX1958 = 2.2V, VOUT for MAX1959 = 1.7V, unless
otherwise noted.) (Note 5)
PARAMETER
CONDITIONS
Supply Voltage Range
Undervoltage Lockout Threshold
Quiescent Current
Quiescent Current in Dropout
Shutdown Supply Current
Rising or falling, hysteresis is 1%
MIN
MAX
UNITS
2.6
TYP
5.5
V
2.20
2.55
V
PWM = AGND (MAX1958)
300
PWM = AGND (MAX1959)
450
MAX1958
550
MAX1959
600
V SHDN1 = 0
6
µA
µA
µA
ERROR AMPLIFIER
OUT Voltage Accuracy
(MAX1958)
OUT Voltage Accuracy
(MAX1959)
OUT Input Current (MAX1958)
VADJ = 1.932V, ILOAD = 0 to 600mA, VPWM = VIN = 3.8V
3.36
3.44
VADJ = 0.426V, ILOAD = 0 to 30mA, VPWM = 0
0.739
0.761
VADJ = 0.426V, ILOAD = 0 to 30mA, VPWM = VIN = 4.2V
0.739
0.761
VADJ = 2.2V, ILOAD = 0 to 600mA, VPWM = VIN = 4V
3.570
3.625
VADJ = 0.9V, ILOAD = 0 to 30mA, VPWM = 0
0.98
1.02
VADJ = 0.9V, ILOAD = 0 to 30mA, VPWM = VIN = 4.2V
0.98
1.02
VOUT = 0.75V
2
6
VOUT = 3.4V
11
25
V
V
µA
VOUT = 1V
2.5
6.5
VOUT = 3.6V
10.0
23.0
ADJ Input Current (MAX1958)
VADJ = 0.426V to 1.932V
-150
+150
nA
ADJ Input Current (MAX1959)
VADJ = 0.9V to 2.2V
-150
+150
nA
Positive COMP Output Current
(MAX1958)
VADJ = 1V, VOUT = 1.5V, VCOMP = 1.25V
-27.0
-6.5
µA
Positive COMP Output Current
(MAX1959)
VADJ = 1V, VOUT =1V, VCOMP = 1.25V
-27.0
-6.5
µA
Negative COMP Output Current
(MAX1958)
VADJ = 1V, VOUT = 2V, VCOMP = 1.25V
6.5
27.0
µA
Negative COMP Output Current
(MAX1959)
VADJ = 1V, VOUT = 1.4V, VCOMP =1.25V
6.5
27.0
µA
1.226
1.275
V
6.25
mV
OUT Input Current (MAX1959)
µA
REFERENCE
REF Output Voltage
REF Load Regulation
10µA < IREF < 100µA
Undervoltage Lockout Threshold
Rising or falling, 1% hysteresis
Supply Rejection
2.6V < VIN < 5.5V
6
0.85
_______________________________________________________________________________________
1.10
V
1.7
mV/V
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
(VINP = VIN = VVCC = V SHDN1 = 3.6V, VPWM = VPGND = VAGND = V SHDN2 = V SHDN3 = 0, VADJ = 1.25V, COMP = IN- = IN+ =
AOUT = TOUT = unconnected, CREF = 0.1µF, TA = -40°C to +85°C, VOUT for MAX1958 = 2.2V, VOUT for MAX1959 = 1.7V, unless
otherwise noted.) (Note 5)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
CONTROLLER
P-Channel On-Resistance
N-Channel On-Resistance
ILX = 180mA, VIN = 3.6V
0.4
ILX = 180mA, VIN = 2.6V
0.5
ILX = 180mA, VIN = 3.6V
0.3
ILX = 180mA, VIN = 2.6V
0.35
P-Channel Current-Limit
Threshold
Ω
Ω
1.1
1.6
A
P-Channel Pulse-Skipping
Current Threshold
VPWM = 0
0.11
0.18
A
LX Leakage Current
VIN = 5.5V
-20
+20
µA
LX RMS Current
(Note 1)
Maximum Duty Cycle
Minimum Duty Cycle
1.0
100
VPWM = 0
Oscillator Frequency
0.8
A
%
0
%
1.2
MHz
LOGIC INPUTS (PWM, SHDN1)
Logic Input High
2.6V < VIN < 5.5V
Logic Input Low
2.6V < VIN < 5.5V
Logic Input Current
VIN = 5.5V
1.6
V
0.6
V
1
µA
_______________________________________________________________________________________
7
MAX1958/MAX1959
ELECTRICAL CHARACTERISTICS (STEP-DOWN CONVERTER) (continued)
MAX1958/MAX1959
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
ELECTRICAL CHARACTERISTICS (OP AMP)
(VINP = VIN = VVCC = V SHDN2 = 2.7V, VAOUT = VVCC/2, RL = ∞ connected from AOUT to VVCC/2, VPGND = VAGND = V SHDN1 =
V SHDN3 = VPWM = VADJ = 0, OUT = LX = TOUT = REF = COMP = unconnected, VCM = 0, TA = -40°C to +85°C, unless otherwise
noted.) (Note 5)
PARAMETER
CONDITIONS
Supply Voltage Range
MIN
TYP
2.6
MAX
UNITS
5.5
V
VVCC = 2.6V
800
Supply Current
VVCC = 5V
900
Input Offset Voltage
VAGND - 0.1V ≤ VCM ≤ VVCC + 0.1V
±3.0
mV
Input Bias Current
VAGND - 0.1V ≤ VCM ≤ VVCC + 0.1V
±100
nA
Input Offset Current
VAGND - 0.1V ≤ VCM ≤ VVCC + 0.1V
±10
nA
VVCC
+ 0.1V
V
V SHDN2 = 0, VVCC = 5.5V
Input Common-Mode Voltage
Range, VCM
µA
2.0
VAGND
- 0.1V
Common-Mode Rejection Ratio,
CMRR
VAGND - 0.1V ≤ VCM ≤ VVCC + 0.1V
60
dB
Power-Supply Rejection Ratio,
PSRR
2.6V < VVCC < 5.5V
70
dB
Large-Signal Voltage Gain, AVOL
VAGND + 0.20V ≤ VOUT ≤ VVCC - 0.20V, RL = 2kΩ
85
Output Voltage Swing High, VOH
VVCC - VVOH, RL = 2kΩ
Output Voltage Swing Low, VOL
VVOL - VAGND, RL = 2kΩ
dB
90
90
mV
0.3 x
VVCC
V
SHDN2 Logic Low
2.6V < VVCC < 5.5V
SHDN2 Logic High
2.6V < VVCC < 5.5V
SHDN2 Input Current
0 < V SHDN2 < VVCC
±120
nA
Capacitive-Load Stability
AVCL = 1V/V (Note 2)
470
pF
Active Discharge Output
Impedance
V SHDN2 = 0, IAOUT = 1mA
500
Ω
8
0.7 x
VVCC
_______________________________________________________________________________________
V
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
(VINP = VIN = VVCC = V SHDN3 = 2.7V, VAGND = VPGND = VPWM = V SHDN1 = V SHDN2 = VADJ = 0, IN- = IN+ = AOUT = COMP = LX =
OUT = REF = unconnected, CTOUT = 0.01µF (min), TA = -40°C to +85°C, unless otherwise noted.) (Note 5)
PARAMETER
CONDITIONS
Temperature Sensor Error
(Note 3)
TYP
MAX
TA = -40°C (Note 2)
-7
+4
TA = +25°C (Note 2)
-2.5
+2.5
TA = +85°C
-2.5
+2.5
Load Regulation
0 ≤ ILOAD ≤ 15µA
Line Regulation
2.6V ≤ VVCC ≤ 5.5V
Quiescent Current
2.6V ≤ VVCC ≤ 5.5V
SHDN3 Logic High Voltage
2.6V < VVCC < 5.5V
SHDN3 Logic Low Voltage
2.6V < VVCC < 5.5V
SHDN3 Current
VVCC = 5.5V
Note 2:
Note 3:
Note 4:
Note 5:
MIN
UNITS
°C
-5
mV
-2.3
mV/V
18
µA
1.6
V
0.6
V
1
µA
Guaranteed by design, not production tested.
VTOUT = (-4 x 10-6) ✕ (T2°C) - (1.13 ✕ 10-2) ✕ (T°C) + 1.8708V.
Linearized gain = VTOUT = -11.64mV/°C + 1.8778V.
Specifications to -40°C are guaranteed by design and not subject to production test.
Typical Operating Characteristics
(TA = +25°C, unless otherwise noted.)
SKIP MODE
VIN = 3.6V
75
PWM
VIN = 4.2V
70
EFFICIENCY (%)
SKIP MODE
PWM
V = 4.2V
VIN = 3.6V IN
80
SKIP MODE
VIN = 4.2V
70
PWM
VIN = 3.6V
60
50
PWM
VIN = 4.2V
40
65
100
1000
SKIP MODE
VIN = 4.2V
70
PWM
VIN = 3.6V
60
PWM
VIN = 4.2V
VOUT = 1.5V
VOUT = 2.5V
40
30
LOAD CURRENT (mA)
SKIP MODE
VIN = 3.6V
80
50
VOUT = 3.4V
60
10
90
80
EFFICIENCY (%)
EFFICIENCY (%)
85
SKIP MODE
VIN = 3.6V
90
100
MAX1958/59 toc02
MAX1958/59 toc01
95
90
EFFICIENCY vs. LOAD CURRENT
EFFICIENCY vs. LOAD CURRENT
100
MAX1958/59 toc03
EFFICIENCY vs. LOAD CURRENT
100
10
100
LOAD CURRENT (mA)
1000
10
100
1000
LOAD CURRENT (mA)
_______________________________________________________________________________________
9
MAX1958/MAX1959
ELECTRICAL CHARACTERISTICS (TEMPERATURE SENSOR)
Typical Operating Characteristics (continued)
(TA = +25°C, unless otherwise noted.)
SUPPLY CURRENT vs. INPUT VOLTAGE
SKIP MODE
150
100
210
190
170
150
130
110
90
50
VOUT = 0.75V
PWM = IN
MAX1958
5
SUPPLY CURRENT (mA)
200
PWM = AGND
VOUT = 1.5V
MAX1958
230
6
MAX1958/59 toc05
250
250
SUPPLY CURRENT (µA)
MAX1958/59 toc04
300
SUPPLY CURRENT vs. INPUT VOLTAGE
FORCED PWM
MAX1958/59 toc06
DROPOUT VOLTAGE ACROSS P-CHANNEL
MOSFET vs. LOAD CURRENT
DROPOUT VOLTAGE (mV)
MAX1958/MAX1959
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
4
3
2
1
70
50
0
0
100 200 300 400 500 600 700 800
0
2.0
2.5
3.0
3.5
4.0
4.5
5.0
2.0
INPUT VOLTAGE (V)
LOAD CURRENT (mA)
2.5
3.0
3.5
4.0
4.5
INPUT VOLTAGE (V)
MEDIUM-LOAD SWITCHING WAVEFORMS
(ILOAD = 300mA)
HEAVY-LOAD SWITCHING WAVEFORMS
(ILOAD = 600mA)
MAX1958/59 toc08
MAX1958/59 toc07
LX
5V/div
LX
5V/div
ILX
100mA/div
ILX
100mA/div
VOUT
AC-COUPLED
10mV/div
VOUT
AC-COUPLED
10mV/div
400ns/div
400ns/div
LIGHT-LOAD SWITCHING WAVEFORMS
(PWM = IN, ILOAD = 30mA)
LIGHT-LOAD SWITCHING WAVEFORMS
(PWM = AGND, ILOAD = 30mA)
MAX1958/59 toc09
MAX1958/59 toc10
LX
5V/div
LX
5V/div
ILX
100mA/div
ILX
100mA/div
VOUT
AC-COUPLED
10mV/div
400ns/div
10
5.5
VOUT
AC-COUPLED
10mV/div
400ms/div
______________________________________________________________________________________
5.0
5.5
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
ENTERING AND EXITING SHUTDOWN
MAX1958 ADJ TRANSIENT
MAX1958/59 toc11
MAX1958/59 toc12
3.4V
5V/div
VSHDN
VOUT
0.75V
IIN
50mA/div
VOUT
1.932V
VADJ
1V/div
0.426V
400µs/div
10µs/div
LOAD TRANSIENT
PWM = AGND
LOAD TRANSIENT
PWM = IN
MAX1958/59 toc13
VOUT
AC-COUPLED
MAX1958/59 toc14
100mV/div
VOUT
AC-COUPLED
100mV/div
400mA
IOUT
400mA
IOUT
30mA
30mA
COUT = 10µF
COUT = 10µF
100µs/div
100µs/div
LOAD TRANSIENT
OP AMP SUPPLY CURRENT
vs. INPUT VOLTAGE
MAX1958/59 toc15
ICC (µA)
10mV/div
4V
3V
VIN
450
TA = +125°C
400
TA = +85°C
350
TA = +25°C
300
MAX1958/59 toc16
VOUT
AC-COUPLED
500
TA = -40°C
250
200
1ms/div
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
VCC (V)
______________________________________________________________________________________
11
MAX1958/MAX1959
Typical Operating Characteristics (continued)
(TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics (continued)
(TA = +25°C, unless otherwise noted.)
OP AMP
INPUT OFFSET VOLTAGE
vs. COMMON-MODE VOLTAGE
600
MAX1958/59 toc17
TA = +125°C
VVCC = 2.5V
500
TA = +85°C
500
TA = +85°C
400
VOS (µV)
TA = +25°C
300
200
TA = +25°C
300
200
TA = -40°C
TA = -40°C
100
100
0
0
0
0.5
1.0
1.5
2.0
2.5
0
2
3
4
5
VCM (V)
OP AMP
INPUT BIAS CURRENT
vs. COMMON-MODE VOLTAGE
OP AMP
OUTPUT SOURCE CURRENT
vs. OUTPUT VOLTAGE
VVCC = 5.5V
TA = -40°C
15
14
MAX1958/59 toc19
20
VVCC = 5.5V
12
TA = +125°C
6
10
ISOURCE (mA)
10
1
VCM (V)
MAX1958/59 toc20
VOS (µV)
TA = +125°C
VVCC = 5.5V
400
IBIAS (nA)
MAX1958/59 toc18
OP AMP
INPUT OFFSET VOLTAGE
vs. COMMON-MODE VOLTAGE
600
5
TA = +85°C
0
8
VVCC = 2.5V
6
4
-5
2
-10
TA = +25°C
0
-15
1
2
3
4
5
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
6
VCM (V)
VAOUT (V)
OP AMP
OUTPUT SINK CURRENT
vs. OUTPUT VOLTAGE
OP AMP
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
0
MAX1958/59 toc21
50
45
40
-10
-20
35
-30
VVCC = 5.5V
25
20
15
VVCC = 2.5V
10
-40
-50
-60
-70
-80
5
-90
0
-100
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
VAOUT (V)
12
PSRR (dB)
30
MAX1958/59 toc22
0
ISINK (mA)
MAX1958/MAX1959
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
0.1
1
10
100
1k
FREQUENCY (Hz)
______________________________________________________________________________________
10k
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
OP AMP
SMALL-SIGNAL TRANSIENT
RESPONSE (NONINVERTING)
OP AMP
GAIN AND PHASE vs. FREQUENCY
MAX1958/59 toc23
80
MAX1958/59 toc24
90
2kΩ || 470pF
60
30
40
-30
20
-90
PHASE
GAIN
0
PHASE (DEGREES)
GAIN (dB)
20mV/div
IN
20mV/div
-150
-20
-210
-40
OUT
-270
0.1
1
10
100
1k
4µs/div
10k
FREQUENCY (Hz)
OP AMP
LARGE-SIGNAL TRANSIENT
RESPONSE (NONINVERTING)
OP AMP
SMALL-SIGNAL TRANSIENT
RESPONSE (INVERTING)
MAX1958/59 toc26
MAX1958/59 toc25
VVCC = 5V
IN
2V/div
20mV/div
IN
20mV/div
2V/div
OUT
OUT
40µs/div
4µs/div
OP AMP
LARGE-SIGNAL TRANSIENT
RESPONSE (INVERTING)
TEMPERATURE SENSOR TOUT VOLTAGE
vs. TEMPERATURE
MAX1958/59 toc28
MAX1958/59 toc27
VVCC = 5V
2.25
IN
2V/div
TOUT (V)
1.75
2V/div
1.25
0.75
OUT
0.25
40µs/div
-40 -25 -10 5
20 35 50 65 80 95 110 125
TEMPERATURE (°C)
______________________________________________________________________________________
13
MAX1958/MAX1959
Typical Operating Characteristics (continued)
(TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics (continued)
(TA = +25°C, unless otherwise noted.)
TEMPERATURE SENSOR
SUPPLY CURRENT vs. INPUT VOLTAGE
TEMPERATURE SENSOR
ERROR vs. TEMPERATURE
0.5
0
-0.5
MAX1958/59 toc30
1.0
20
18
16
SUPPLY CURRENT (µA)
MAX1958/59 toc29
1.5
ERROR (°C)
MAX1958/MAX1959
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
14
12
10
8
6
4
-1.0
2
0
-1.5
-40 -25 -10
5
20
35
50
65
80
95
0
1
2
3
4
5
6
INPUT VOLTAGE (V)
TEMPERATURE (°C)
Pin Description
14
PIN
NAME
1
AOUT
FUNCTION
Op-Amp Output. AOUT discharges to AGND during shutdown.
2
SHDN2
Shutdown Control Input for the Op Amp. Drive to AGND to shut down the op amp. Connect to VCC or
drive high for normal operation.
3
AGND
Analog Ground. Ground for op amp, temperature sensor, and the precision circuits in the DC-to-DC
regulator. Connect to pin 6.
4
TOUT
Analog Voltage Output Representing the Die Temperature. Bypass to AGND with a 0.01µF capacitor.
5
REF
6
AGND
Analog Ground. Connect to pin 3.
7
COMP
Compensation. Typically, connect a 22pF capacitor from COMP to AGND and a 9.1kΩ resistor and
560pF capacitor in series from COMP to AGND to stabilize the regulator (see the Compensation and
Stability section).
8
ADJ
9
SHDN3
10
OUT
11
PGND
12
LX
Inductor Connection to the Internal Power MOSFETs
13
IN
Low-Current Supply Voltage Input. Connect to INP at the IC.
Internal 1.25V Reference. Bypass to AGND with a 0.1µF capacitor.
External Reference Input. Connect ADJ to the output of a D/A converter for dynamic adjustment of the
regulator’s output voltage. OUT regulates at (1.76 x VADJ) for the MAX1958 and (2 x VADJ - 0.8V) for
the MAX1959.
Shutdown Control Input for the Temperature Sensor. Drive to AGND to shut down the temperature
sensor. Connect to VCC or drive high for normal operation.
Output Voltage Feedback. Connect OUT directly to the output. OUT is high impedance during
shutdown.
Power Ground for the DC-to-DC Converter
______________________________________________________________________________________
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
PIN
NAME
FUNCTION
14
INP
15
PWM
16
INP
17
SHDN1
18
VCC
Supply Input for Op Amp and Temperature-Sensor Circuitry. Connect to INP through an RC filter.
19
IN+
Noninverting Input for the Op Amp
20
IN-
Inverting Input for the Op Amp
—
Exposed
Paddle
High-Current Supply Voltage Input. Connect to a 2.6V to 5.5V source. Bypass to PGND with a lowESR 4.7µF capacitor. Connect to pin 16.
PWM/Skip-Mode Input. Drive low to use PWM mode at medium and heavy loads and pulse-skipping
mode at light loads. Drive high to force PWM mode at all loads.
Supply Voltage Input. Connect to pin 14.
Shutdown Control Input for the Converter. Drive to AGND to shut down the converter. Connect to IN
or drive high for normal operation.
Connect to Large AGND Plane. Internally connected to AGND.
Detailed Description
PWM Step-Down DC-to-DC Converter
The PWM step-down DC-to-DC converter is optimized
for low-voltage, battery-powered applications where high
efficiency and small size are priorities. It is specifically
intended to power the linear HBT PA in N-CDMA/
W-CDMA handsets. An analog control signal (ADJ)
dynamically adjusts the converter’s output voltage from
0.75V to 3.4V (MAX1958) or 1V to 3.6V (MAX1959) with a
settling time of approximately 30µs. The MAX1958/
MAX1959 operate at a high 1MHz switching frequency
that reduces external component size. The IC contains
an internal synchronous rectifier that increases efficiency
and eliminates the need for an external Schottky diode.
The normal operating mode uses constant-frequency
PWM switching at medium and heavy loads and pulse
skips at light loads to reduce supply current and extend
battery life. An additional forced-PWM mode switches at
a constant frequency, regardless of load, to provide a
well-controlled noise spectrum for easier filtering in
noise-sensitive applications. The MAX1958/MAX1959
are capable of 100% duty-cycle operation to increase
efficiency in dropout. Battery life is maximized with a
0.1µA (typ) logic-controlled shutdown mode.
Normal-Mode Operation
Connecting PWM to GND enables PWM/pulse-skipping
operation. This proprietary control scheme uses pulseskipping mode at light loads to improve efficiency and
reduce quiescent current to 190µA for the MAX1958
and 280µA for the MAX1959. With PWM/pulse-skipping
mode enabled, the MAX1958/MAX1959 initiate pulse-
skipping operation when the peak inductor current
drops below 150mA. During pulse-skipping operation,
switching occurs only as necessary to service the load,
thereby reducing the switching frequency and associated losses in the internal switch, synchronous rectifier,
and inductor.
During pulse-skipping operation, a switching cycle initiates when the error amplifier senses that the output
voltage has dropped below the regulation point. If the
output voltage is low, the high-side P-channel MOSFET
switch turns on and conducts current through the
inductor to the output filter capacitor and load. The
PMOS switch turns off when the output voltage rises
above the regulation point and the error amplifier is satisfied. The MAX1958/MAX1959 then wait until the error
amplifier senses an out-of-regulation output voltage to
start the cycle again.
At peak inductor currents above 150mA, the
MAX1958/MAX1959 operate in PWM mode. During
PWM operation, the output voltage is regulated by
switching at a constant frequency and then modulating
the power transferred to the load using the error comparator. The error amplifier output, the main switch
current-sense signal, and the slope compensation
ramp are all summed at the PWM comparator (see the
Functional Diagram). The comparator modulates the
output power by adjusting the peak inductor current
during the first half of each cycle based on the output
error voltage. The MAX1958/MAX1959 have relatively
low AC loop gain coupled with a high-gain integrator to
enable the use of a small, low-valued output filter
capacitor. The resulting load regulation is ≤1.5% from 0
______________________________________________________________________________________
15
MAX1958/MAX1959
Pin Description (continued)
MAX1958/MAX1959
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
to 600mA. Some jitter is normal during the transition from
pulse-skipping mode to PWM mode with loads around
75mA. This has no adverse impact on regulation.
Forced-PWM Operation
To force PWM operation at all loads, connect PWM to
IN. Forced-PWM operation is desirable in sensitive
RF and data-acquisition applications to ensure that
switching-noise harmonics are predictable and can be
easily filtered. This is to ensure that the switching noise
does not interfere with sensitive IF and data sampling
frequencies. A minimum load is not required during
forced-PWM operation because the synchronous rectifier passes reverse inductor current as needed to allow
constant-frequency operation with no load. ForcedPWM operation has higher quiescent current than
pulse-skipping mode (3mA typically compared to
190µA) due to continuous switching.
100% Duty-Cycle Operation
The maximum on-time can exceed one internal oscillator
cycle, which permits operation at 100% duty cycle. As
the input voltage drops, the duty cycle increases until
the internal P-channel MOSFET stays on continuously.
Dropout voltage at 100% duty cycle is the output current multiplied by the sum of the internal PMOS onresistance (typically 0.25Ω) and the inductor
resistance. Near dropout, cycles may be skipped,
reducing switching frequency. However, voltage ripple
remains small because the current ripple is still low.
Dropout
Dropout occurs when the desired output regulation
voltage is higher than the input voltage minus the voltage
drops in the circuit. In this situation, the duty cycle is
100%, so the high-side P-channel MOSFET is held on
continuously and supplies current to the output up to
the current limit. The output voltage in dropout falls to
the input voltage minus the voltage drops. The largest
voltage drops occur across the inductor and high-side
MOSFET. The dropout voltage increases as the load
current increases.
During dropout, the high-side, P-channel MOSFET
turns on and the controller enters a low-current consumption mode. Every 6µs (six cycles), the MAX1958/
MAX1959 check to see if the device is in dropout. The
IC remains in this mode until it is no longer in dropout.
COMP Clamp
The MAX1958/MAX1959 compensation network has a
1V to 2.25V error-regulation range. The clamp optimizes transient response by preventing the voltage on
COMP from rising too high or falling too low.
16
Undervoltage Lockout (UVLO)
The DC-to-DC converter portion of the MAX1958/
MAX1959 is disabled if battery voltage on IN is below the
UVLO threshold of 2.35V (typ). LX remains high impedance until the supply voltage exceeds the UVLO threshold. This guarantees the integrity of the output voltage
and prevents excessive current during startup and as
the battery supply drops in voltage during use. The op
amp and temperature sensor are not connected to the
UVLO and therefore continue to operate normally.
Synchronous Rectification
An N-channel synchronous rectifier operates during the
second half of each switching cycle (off-time). When the
inductor current falls below the N-channel current-comparator threshold or when the PWM reaches the end of
the oscillator period, the synchronous rectifier turns off.
This prevents reverse current flow from the output to
the input in pulse-skipping mode. During PWM operation, small amounts of reverse current flow through the
N-channel MOSFET during light loads. This allows regulation with a constant switching frequency and eliminates minimum load requirements for fixed-frequency
operation. The N-channel reverse-current comparator
threshold is -500mA. The N-channel zero-crossing
threshold in pulse-skipping mode is 20mA (see the
Forced-PWM Operation and Normal-Mode Operation
sections)
Shutdown Mode
Driving SHDN1 to ground puts the DC-to-DC converter
into shutdown mode. In shutdown mode, the reference,
control circuitry, internal-switching MOSFET, and synchronous rectifier turn off and the output (LX) becomes
high impedance. Input current falls to 0.1µA (typ) during shutdown mode. Drive SHDN1 high for normal
operation.
Thermal Limit
The thermal limit is set at approximately +160°C and
shuts down only the converter. In this state, both main
MOSFETs are turned off. Once the IC cools by 15°C,
the converter operates normally. A continuous overload
condition results in a pulsed output. During thermallimit conditions, the op amp and temperature sensor
continue to operate.
Current-Sense Comparators
The IC uses several internal current-sense comparators.
In PWM operation, the current-sense amplifier, combined
with the PWM comparator, sets the cycle-by-cycle current limit and provides improved load and line response.
This allows tighter specification of the inductor-saturation
current limit to reduce inductor cost. A second 150mA
current-sense comparator monitors the current through
______________________________________________________________________________________
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
Rail-to-Rail Op Amp
The MAX1958/MAX1959 contain a rail-to-rail op amp
that can be used to provide bias for the HBT PA. As the
power needs of the PA change, the op amp can be
used to dynamically change the bias point for the PA in
order to optimize efficiency.
Rail-to-Rail Input Stage
The op amp in the MAX1958/MAX1959 has rail-to-rail
input and output stages that are specifically designed
for low-voltage, single-supply operation. The input
stage consists of composite NPN and PNP differential
stages, which operate together to provide a commonmode range extending beyond both supply rails. The
crossover region of these two pairs occurs halfway
between VCL and AGND. The input offset voltage is
typically ±400µV.
The MAX1958/MAX1959 op amp inputs are protected
from large differential input voltages by internal 5.3kΩ
series resistors and back-to-back triple-diode stacks
across the inputs (Figure 1). For differential input voltages much less than 2.1V (three diode drops), input
resistance is typically 4MΩ. For differential voltages
greater than 2.1V, input resistance is around 10.6kΩ,
and the input bias current can be approximated by the
following equation:
IBIAS =
(VDIFF - 2.1V)
10.6kΩ
In the region where the differential input voltage
increases to about 2.1V, the input resistance decreases
exponentially from 4MΩ to 10.6kΩ as the diodes begin
to conduct. It follows that the bias current increases
with the same curve.
MAX1958/MAX1959
the P-channel switch and controls entry into pulse-skipping mode. A third current-sense comparator monitors
current through the internal N-channel MOSFET to prevent excessive reverse currents and determines when to
turn off the synchronous rectifier. A fourth comparator
used at the P-channel MOSFET detects overcurrent. This
protects the system, external components, and internal
MOSFETs during overload conditions.
Figure 1. Input Protection Circuit
VIN+
2V/div
VAOUT
2V/div
Figure 2. Op-Amp Output Voltage Swing
Rail-to-Rail Output Stage
The MAX1958/MAX1959 op amp can drive down to a
2kΩ load and still typically swing within 35mV of the
supply rails. Figure 2 shows the output voltage swing of
the MAX1958 configured with AV = 1.57V/V and with
VVCC at 4.2V.
Temperature Sensor
The MAX1958/MAX1959 analog temperature sensor’s
output voltage is a linear function of its die temperature.
The slope of the output voltage is approximately
-11.64mV/°C and there is a 1.878V offset at 0°C to allow
measurement of positive temperatures. The temperature sensor functions from -40°C to +125°C .The temperature error is less than ±2.5°C at temperatures from
+25°C to +85°C.
Nonlinearity
The benefit of silicon analog temperature sensors over
thermistors is the linearity over extended temperatures.
The nonlinearity of the MAX1958/MAX1959 is typically
±0.4% over the 0°C to +85°C temperature range.
______________________________________________________________________________________
17
MAX1958/MAX1959
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
Transfer Function
The temperature-to-voltage transfer function has an
approximately linear negative slope and can be
described by the following equation:
VTOUT = −11.64
mV
× T + 1.878V
°C
T is the die temperature in °C. Therefore:
T=
VTOUT - 1.878V
-11.64mV / °C
To account for the small amount of curvature in the
transfer function, use the equation below to obtain a
more accurate temperature reading:
VTOUT = (-4 × 10-6 × T 2 ) + (-1.13 × 10-2 × T) + 1.8708V
Applications Information
PWM Step-Down DC-to-DC Converter
Setting the Output Voltage
The MAX1958/MAX1959 are optimized for highest system efficiency when applying power to a linear HBT PA
in N-CDMA/W-CDMA handsets. The supply voltage to
the PA is reduced (from 3.4V to as low as 0.75V for
MAX1958) when transmitting at less than full power to
greatly conserve supply current and extend battery life.
The typical load profile for a W-CDMA PA can be seen
in Figure 3. The MAX1958/MAX1959 dramatically
reduce battery drain in these applications.
The MAX1958 output voltage is dynamically adjustable
from 0.75V to 3.4V and MAX1959 output voltage is
dynamically adjustable from 1V to 3.6V using the ADJ
input. The input voltage cannot be lower than the output
voltage. VOUT can be adjusted during operation by driving ADJ with an external DAC. The output voltage for
the MAX1958 is determined as:
VOUT = 1.76 × VADJ
The output voltage for the MAX1959 is determined as:
VOUT = 2 × VADJ - 0.8V
The MAX1958/MAX1959 output voltage responds to a
full-scale change in voltage and current in approximately 30µs.
18
Compensation and Stability
The MAX1958/MAX1959 are externally compensated
with a resistor and a capacitor (R C and CC, Typical
Application Circuit) in series from COMP to AGND. An
additional capacitor (C f ) is required from COMP to
AGND. The capacitor, CC, integrates the current from the
transimpedance amplifier, averaging output capacitor
ripple. This sets the device speed for transient response
and allows the use of small ceramic output capacitors
because the phase-shifted capacitor ripple does not disturb the current-regulation loop. The resistor, RC, sets the
proportional gain of the output error voltage by a factor of
gm ✕ RC. Increasing this resistor also increases the sensitivity of the control loop to output ripple.
The series resistor and capacitor set a compensation
zero that defines the system’s transient response. The
load creates a dynamic pole, shifting in frequency with
changes in load. As the load decreases, the pole
frequency decreases. System stability requires that the
compensation zero must be placed to ensure adequate
phase margin (at least 30° at unity gain). The following
is a design procedure for the compensation network.
Select an appropriate converter bandwidth (fC) to stabilize the system while maximizing transient response.
This bandwidth should not exceed 1/10 of the switching
frequency.
Calculate the compensation capacitor, CC, based on
this bandwidth:
 V
  1  
1
R2 
OUT
CC = 
×  gm ×
×
 ×



2πfC
R1+ R2
 IOUT(MAX)   RCS 
Resistors R1 and R2 are internal to the MAX1958/
MAX1959. For the MAX1958, use R1 = 95kΩ and R2 =
125kΩ as nominal values for calculations. For the
MAX1959, use R1 = 125kΩ and R2 = 125kΩ as nominal
values for calculations. IOUT(MAX) is the maximum output current, RCS = 0.5V/A, and gm = 250µS. Select the
closest standard value CC that gives an acceptable
bandwidth.
Calculate the equivalent load impedance, RL, by:
RL =
VOUT
IOUT(MAX)
Calculate the compensation resistance (RC) to cancel
out the dominant pole created by the output load and
the output capacitance:
1
1
=
2π × RL × COUT 2π × RC × CC
______________________________________________________________________________________
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
R × COUT
RC = L
CC
Calculate the high-frequency compensation pole to
cancel the zero created by the output capacitor’s
equivalent series resistance (ESR):
1
1
=
2π × RESR × COUT 2π × RC × C f
Solving for Cf gives:
R
× COUT
Cf = ESR
RC
Use the calculated value for Cf or 22pF, whichever is
larger.
Inductor Selection
There are several parameters that must be examined
when determining an optimum inductor value. Input
voltage, output voltage, load current, switching frequency, and LIR. LIR is the ratio of inductor current ripple to DC load current. A higher LIR value allows for a
smaller inductor, but results in higher losses and higher
output ripple current. A good compromise between
size, efficiency, and cost is an LIR of 30%. Once all the
parameters are chosen, the inductor value is determined as follows:
L=
VOUT × ( VIN - VOUT )
VIN × fS × ILOAD(MAX) × LIR
where fS is the switching frequency (1MHz). Choose a
standard-value inductor close to the calculated value.
The exact inductor value is not critical and can be adjusted in order to make trade-offs between size, cost, and
efficiency. Lower inductor values minimize size and cost,
but they also increase the output ripple and reduce the
efficiency due to higher peak currents. On the other
hand, higher inductor values increase efficiency, but
eventually resistive losses due to extra turns of wire
exceed the benefit gained from lower AC current levels.
For any area-restricted applications, find a low-core-loss
inductor having the lowest possible DC resistance. Ferrite
cores are often the best choice. The inductor’s saturation
current rating must exceed the expected peak inductor
current (IPEAK). Consult the inductor manufacturer for saturation current ratings. Determine IPEAK as:
 LIR 
IPEAK = ILOAD(MAX) + 
 ×I
 2  LOAD(MAX)
Input Capacitor Selection
The input capacitor (CIN) reduces the current peaks
drawn from the battery or input power source and
reduces switching noise in the IC. The impedance of
the input capacitor at the switching frequency should
be less than that of the input source so that highfrequency switching currents are not required from the
source.
The input capacitor must meet the ripple current
requirement (IRMS) imposed by the switching currents.
Nontantalum chemistries (ceramic, aluminum, or organic) are preferred due to their resistance to power-up
surge currents. IRMS is calculated as follows:
IRMS =
ILOAD × VOUT × (VIN - VOUT )
VIN
Output Capacitor Selection
The output capacitor is required to keep the output
voltage ripple small and to ensure stability of the regulation control loop. The output capacitor must have low
impedance at the switching frequency. An additional
constraint on the output capacitor is load transients. If it
is desired for the output voltage to swing from 0.75V to
3.4V in 30µs, the output capacitor should be approximately 4.7µF or less. Ceramic capacitors are recommended. The output ripple is approximately:


1
VRIPPLE = LIR × ILOAD(MAX) ×  ESR +
2π × fS × COUT 

See the Compensation and Stability section for a discussion of the influence of output capacitance and ESR
on regulation control-loop stability.
Rail-to-Rail Op Amp
Shutdown Mode
The MAX1958/MAX1959 op amp (Figure 4) features a
low-power shutdown mode. When SHDN2 is pulled low,
the supply current for the amplifier drops to 0.1µA, the
amplifier is disabled, and the output is actively discharged to AGND with an internal 100Ω switch. Pulling
SHDN2 high enables the amplifier.
Due to the output leakage currents of three-state
devices and the small internal pullup current for
SHDN2, do not leave SHDN2 unconnected. Floating
______________________________________________________________________________________
19
MAX1958/MAX1959
Solving for RC gives:
Power-Supply Bypass
The power-supply voltage applied to VCC for the op
amp and temperature sensor in the MAX1958/
MAX1959 circuit is filtered from INP. Connect V CC to
INP through an RC network (R2 and C7 in Figure 4) to
ensure a quiet power supply.
3.4
3.0
PA SUPPLY VOLTAGE (V)
MAX1958/MAX1959
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
Temperature Sensor
The temperature sensor provides information about the
MAX1958/MAX1959 die temperature. The voltage at
TOUT (VTOUT) is related to die temperature as follows:
1.0
VTOUT = (-4 × 10-6 × T 2 ) + (-1.13 × 10-2 × T) + 1.8708V
0.4
0.0
0 30
300
PA SUPPLY CURRENT (mA)
600
Figure 3. Typical W-CDMA Power Amplifier Load Profile
SHDN2 may result in indeterminate logic levels, and
could adversely affect op-amp operation.
Driving Capacitive Loads
The MAX1958/MAX1959 op amp is unity-gain stable for
capacitive loads up to 470pF. Applications that require
a greater capacitive drive capability should use an isolation resistor (R ISO ) between the output and the
capacitive load (Figure 5). Note that this alternative
results in a loss of gain accuracy because RISO forms a
voltage-divider with RLOAD.
For stable operation, bypass TOUT to AGND with at
least a 0.01µF capacitor.
Temperature Sensor Error Due to Die Self-Heating
When the 800mA converter and the op amp are both
operated at heavy load while the temperature sensor is
enabled, the indicated temperature at TOUT deviates
several degrees from the actual ambient temperature
due to die self-heating effects. At light loads, when die
self-heating is low, TOUT tends to be a good approximation of the ambient temperature. At heavier loads,
the die self-heating is appreciable; TOUT gives a good
approximation of the die temperature, which can be
several degrees higher than the ambient temperature.
Sensing Circuit Board and Ambient Temperature
Temperature sensors like those found in the
MAX1958/MAX1959 that sense their own die tempera-
Table 1. Recommended Inductors
PART NO.
INDUCTANCE
(µH)
DC RESISTANCE
(mΩ)
RATED DC MAX
CURRENT
(mA)
DIMENSIONS
LxWxH
(mm)
CDRH3D16-4R7
4.7
80
900
3.8 x 3.8 x 1.8
972AS-4R7M = P5
4.7
220
960
4.6 x 4.6 x 1.2
CMD4D11-4R7
4.7
166
750
3.5 x 5.3 x 1.2
976AS-4R7 = P5
4.7
320
740
3.6 x 3.6 x 1.2
Murata
LQH3C4R7M34
4.7
200
450
2.5 x 3.2 x 2
Sumida
CDRH2D11-4R7
4.7
170
500
3.2 x 3.2 x 1.2
LQH1C4R7M04
4.7
650
0.34
1.6 x 3.2 x 2
MANUFACTURER
800mA Application
Sumida
Toko
700mA Application
Sumida
Toko
400mA Application
300mA Application
Murata
Note: Efficiency may vary depending upon the inductor’s characteristics. Consult the inductor manufacturer for saturation current ratings.
20
______________________________________________________________________________________
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
MAX1958/MAX1959
VIN
2.6V TO 5.5V
 R6 
VAOUT = VIN+ × 1+

 R7 
R2
20Ω
INP
SHDN2
VCC
C7
0.1µF
OFFSET
MAX1958/
MAX1959
IN+
AOUT
VREF
R6
6.8kΩ
INR7
12kΩ
HBT
PA
Figure 4. Op-Amp Configuration
tures must be mounted on, or close to, the object
whose temperature they are intended to measure.
There is a good thermal path between the exposed
paddle of the package and the IC die; therefore, the
MAX1958/MAX1959 can accurately measure the
temperature of the circuit board to which they are soldered. If the sensor is intended to measure the temperature of a heat-generating component on the circuit
board, it should be mounted as close as possible to
that component and should share supply and ground
traces (if they are not noisy) with that component where
possible. This maximizes the heat transfer from the
component to the sensor.
The thermal path between the plastic package and the
die is not as good as the path through the exposed
paddle, so the MAX1958/MAX1959, like all temperature
sensors in plastic packages, are less sensitive to the
temperature of the surrounding air than they are to the
temperature of its exposed paddle. They can be successfully used to sense ambient temperature if the circuit board is designed to track the ambient
temperature.
As with any IC, the wiring and circuits must be kept
insulated and dry to avoid leakage and corrosion,
especially if the part is operated at cold temperatures
where condensation can occur.
MAX1958/
MAX1959
RISO
100Ω
AOUT
R6
CLOAD
RLOAD
IN-
R7
Figure 5. Configuration for Driving Larger Capacitive Loads
The junction-to-ambient thermal resistance (θJA) is the
parameter used to calculate the rise of a device junction temperature (TJ) due to its power dissipation. The
θJA for the 20-pin QFN package is +50°C/W. For the
MAX1958/MAX1959, use the following equation to
calculate the rise in die temperature:
(
TJ = TA + Θ JA × PD(CONVERTER) + PD(OPAMP) + PD( TEMPSENSOR)
)
The power dissipated by the DC-to-DC converter dominates in this equation. It is then reasonable to assume
______________________________________________________________________________________
21
MAX1958/MAX1959
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
that the rise in die temperature due to the converter is a
good approximation of the total rise in die temperature.
Therefore:
(
)
TJ ≈ TA + Θ JA × PD(CONVERTER) = TA + Θ JA × (VIN × IIN - VOUT × IOUT )
This equation assumes that the losses in the inductor
are relatively small. For inductors with high DC resistance, inductor loss must be accounted for in the calculation. The temperature rise due to power dissipation
by the converter can be quite significant.
PC Board Layout and Routing
High switching frequencies and large peak currents
make PC board layout a very important part of design.
Good design minimizes EMI, noise on the feedback
paths, and voltage gradients in the ground plane, all of
which can cause instability or regulation errors.
Connect the inductor, input filter capacitor, and output
filter capacitor as close together as possible and keep
their traces short, direct, and wide. Connect their
ground pins at a single common node in a star ground
configuration. Keep noisy traces, such as those from
the LX pin, away from the output feedback network.
Position the bypass capacitors as close as possible to
their respective pins to minimize noise coupling. For
optimum performance, place input and output capacitors as close to the device as possible. Connect AGND
and PGND to the highest quality system ground. The
MAX1958 evaluation kit illustrates an example PC
board layout and routing scheme.
Optimize performance of the op amp by decreasing the
amount of stray capacitance at the op amp’s inputs
and output. Decrease stray capacitance by placing
external components as close to the device as possible
to minimize trace lengths and widths.
Typical Operating Circuit
VIN
2.6V TO 5.5V
L1
4.7µH
SUMIDA
CDRH3D16-4R7
INP
IN
LX
C1
4.7µF
C2
4.7µF
PGND
PWM
SHDN1
OUT
R2
20Ω
AOUT
VREF
VCC
R6
6.8kΩ
VCC
C7
0.1µF
MAX1958/
MAX1959
INR7
12kΩ
HBT PA
SHDN2
TOUT
SHDN3
DAC
ADJ
VTOUT
RC
9.1kΩ
C6
0.01µF
COMP
Cf
22pF
REF
OFFSET
IN+
AGND
CC
560pF
C5
0.1µF
EXPOSED
PADDLE
22
______________________________________________________________________________________
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
IN
REF
REFERENCE
COMP
COMP
CLAMP
MAX1958/
MAX1959
INP
1MHz
OSCILLATOR
ADJ
ERROR
AMPLIFIER
LX
PWM
CONTROL
SLOPE
COMPENSATION
CURRENT SENSE
PGND
PWM
COMPARATOR
OUT
SHDN1
PWM
VCC
IN+
AOUT
OP AMP
INACTIVE
DISCHARGE
SHDN2
TOUT
TEMPERATURE
SENSOR
AGND
AGND
SHDN3
Chip Information
TRANSISTOR COUNT: 3704
PROCESS: BiCMOS
______________________________________________________________________________________
23
MAX1958/MAX1959
Functional Diagram
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.)
D2
0.15 C A
D
b
CL
0.10 M C A B
D2/2
D/2
PIN # 1
I.D.
QFN THIN.EPS
MAX1958/MAX1959
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
k
0.15 C B
PIN # 1 I.D.
0.35x45
E/2
E2/2
CL
(NE-1) X e
E
E2
k
L
DETAIL A
e
(ND-1) X e
CL
CL
L
L
e
e
0.10 C
A
C
0.08 C
A1 A3
PROPRIETARY INFORMATION
TITLE:
PACKAGE OUTLINE
16, 20, 28, 32L, QFN THIN, 5x5x0.8 mm
APPROVAL
COMMON DIMENSIONS
DOCUMENT CONTROL NO.
REV.
21-0140
C
1
2
EXPOSED PAD VARIATIONS
NOTES:
1. DIMENSIONING & TOLERANCING CONFORM TO ASME Y14.5M-1994.
2. ALL DIMENSIONS ARE IN MILLIMETERS. ANGLES ARE IN DEGREES.
3. N IS THE TOTAL NUMBER OF TERMINALS.
4. THE TERMINAL #1 IDENTIFIER AND TERMINAL NUMBERING CONVENTION SHALL CONFORM TO JESD 95-1
SPP-012. DETAILS OF TERMINAL #1 IDENTIFIER ARE OPTIONAL, BUT MUST BE LOCATED WITHIN THE
ZONE INDICATED. THE TERMINAL #1 IDENTIFIER MAY BE EITHER A MOLD OR MARKED FEATURE.
5. DIMENSION b APPLIES TO METALLIZED TERMINAL AND IS MEASURED BETWEEN 0.25 mm AND 0.30 mm
FROM TERMINAL TIP.
6. ND AND NE REFER TO THE NUMBER OF TERMINALS ON EACH D AND E SIDE RESPECTIVELY.
7. DEPOPULATION IS POSSIBLE IN A SYMMETRICAL FASHION.
8. COPLANARITY APPLIES TO THE EXPOSED HEAT SINK SLUG AS WELL AS THE TERMINALS.
9. DRAWING CONFORMS TO JEDEC MO220.
10. WARPAGE SHALL NOT EXCEED 0.10 mm.
PROPRIETARY INFORMATION
TITLE:
PACKAGE OUTLINE
16, 20, 28, 32L, QFN THIN, 5x5x0.8 mm
APPROVAL
DOCUMENT CONTROL NO.
REV.
21-0140
C
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.
24 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
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Printed USA
is a registered trademark of Maxim Integrated Products.